JP3503385B2 - Navigation system and medium storing navigation program used therein - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted or portable navigation system and a medium storing a navigation program used therein, and particularly to a navigation system for displaying topographical information and map information in a stereoscopic bird's-eye view and a navigation program used therein. Regarding the medium.

[0002]

2. Description of the Related Art Conventionally, as a vehicle-mounted or portable navigation system, one described in Japanese Patent Application Laid-Open No. 7-220055, which describes the invention of the applicant of the present application, is known. This conventional navigation system uses a GPS (Global Positioning S).
system) or the self-contained navigation system to detect the current position of the user and specify the detected current position, or specify a specific position using the keyboard or remote controller to determine the display reference point The viewpoint coordinates and the line-of-sight direction are calculated based on the traveling direction, and perspective projection conversion is performed on the map data registered in the external storage device to form a bird's-eye view as shown in FIG.

[0003]

In such a conventional navigation system, detailed (large-scale) map information is displayed and displayed in an area near a certain display reference point such as the current position of the user. There is an advantage that it is possible to intuitively grasp the road condition up to a distant place by displaying the map information in which the display area expands (the scale is small) as the distance from the reference point increases.

However, in such conventional route guidance, the map data to be used is basically described in a two-dimensional coordinate system, and the ground that is the background of the map is regarded as a flat surface and displayed. Therefore, the actual ground will be displayed as a flat surface even when displaying the location of terrain with a lot of undulations, especially when displaying the user's current position as the display reference point, which is in agreement with the surrounding real landscape. Without doing so, there was a problem that there was a sense of discomfort in checking the current position on the map and grasping the relationship with the surrounding environment.

Various types of simulation software and game software exist as application software for displaying a three-dimensional model of the terrain, but the displayed terrain does not display information such as road information and place names necessary for route guidance. It cannot be used for a navigation system because the area is limited, or because it only displays a fictitious world unrelated to the actual topography.

The present invention has been made in view of the above conventional problems, and three-dimensionally displays the terrain by using the elevation value data based on the actual terrain, and further, a map display element such as a road or a place name. An object of the present invention is to provide a navigation system capable of displaying a three-dimensional road map that closely resembles the actual terrain by arranging the vehicle on the terrain and creating and displaying the three-dimensional map, and a medium storing the navigation program used for the navigation system. To do.

Another object of the present invention is to set the viewpoint at a height position obtained by adding a predetermined height to the elevation value of the display reference point, so that the elevation value of the display reference point changes in height. (EN) A navigation system capable of displaying a terrain state viewed from a viewpoint having a predetermined relative altitude with respect to the altitude value, and a medium storing a navigation program used for the navigation system.

Still another object of the present invention is to make it easier for a user to understand the state of a road farther than it which is hidden by a nearby high mountain or the like and which cannot be seen so as to distinguish it from other roads. Another object is to provide a navigation system and a medium storing a navigation program used therein.

Still another object of the present invention is to make a character string, which is hidden by a nearby high mountain or the like and cannot be seen, display a point farther than that, as if it is hidden by a nearby high mountain or the like. Another object of the present invention is to provide a navigation system and a medium storing a navigation program used for the navigation system, which can further enhance the realism of a stereoscopic bird's-eye view display.

[0010]

A navigation system according to a first aspect of the present invention comprises a terrain data storage means for storing terrain shape data capable of giving elevation values to terrain plane coordinates, and a map such as roads and place names. Map data storage means for storing position information and incidental information of map display elements displayed above, and display reference points for inputting position coordinates and line-of-sight direction angles for determining the position and direction of the displayed map. Etc. input means and display target area determination for determining a target area (display target area) on the map displayed on the screen according to the display reference point position coordinates and the line-of-sight direction angle input from the display reference point etc. input means Means and the topographical shape data corresponding to the display target area determined by the display target area determining means, is read from the topographical data storage means, and the topographical shape data is read. Of the display reference points based on the terrain shape modeling means for performing the terrain shape modeling and the display reference point position coordinates input from the display reference point input means and the terrain shape model obtained by the terrain shape modeling means. Display reference point altitude determining means for determining the altitude value,
A viewpoint for determining viewpoint coordinates of perspective projection conversion from the display reference point position coordinates and the line-of-sight direction angle input from the display reference point etc. inputting means, and the display reference point elevation value determined by the display reference point elevation determining means. The coordinate determination means and the map display element corresponding to the display target area are read from the map data storage means, and if necessary, the elevation value of each map display element based on the terrain shape model obtained by the terrain shape modeling means. And the map element elevation determining means for creating the display graphic data, and the topography based on the viewpoint coordinates determined by the viewpoint coordinate determining means and the line-of-sight direction angle input from the display reference point input means. Coordinate transformation means for performing perspective projection transformation between the shape model and the map display element for which the elevation value has been determined, and perspective projection transformation performed by the coordinate transformation means And rendering processing means for three-dimensional map to generate an image from the chromatography data is obtained by an image display means for displaying the three-dimensional map image.

According to a second aspect of the present invention, in the navigation system according to the first aspect, the drawing processing means draws the data perspective-transformed by the coordinate transformation means while performing hidden surface removal to render a stereoscopic map image. It is what is output.

According to a third aspect of the present invention, in the navigation system according to the first or second aspect, the drawing processing means includes:
The guide route is drawn with a drawing color or line type different from that of an ordinary road.

According to a fourth aspect of the present invention, in the navigation system of the first to third aspects, the terrain shape modeling means sets sampling points of a predetermined density in the display target area determined by the display target area determining means. , The elevation value z corresponding to the plane coordinates (x, y) of each sampling point is read from the topographical data storage means to generate a three-dimensional sampling point (x, y, z) group, and the three-dimensional sampling point is generated. This is to create an open polyhedral terrain shape model by connecting groups with ridge lines according to a predetermined rule.

According to a fifth aspect of the present invention, in the navigation system according to the fourth aspect, the terrain shape modeling means sets a sampling point group having a high distribution density in a partial area of the display target area near the viewpoint coordinates. A sampling point group having a low distribution density is set in the partial area far from the viewpoint coordinates.

According to a sixth aspect of the present invention, in the navigation system according to the first to fifth aspects, the viewpoint coordinate determining means comprises:
The elevation coordinate value of the viewpoint coordinates is changed according to the display reference point elevation value determined by the display reference point elevation determining means.

According to a seventh aspect of the present invention, in the navigation system according to the sixth aspect, the viewpoint coordinate determining means adds a constant offset to the display reference point elevation value determined by the display reference point elevation determining means. The altitude value of the viewpoint coordinates is determined.

According to an eighth aspect of the present invention, in the navigation system according to the first to seventh aspects, the map element elevation determining means is a map display element in which the map data stored in the map data storage means includes roads and place names. When the position information excluding the altitude is stored in the form of two-dimensional coordinates, the topographical shape model modeled by the topographical shape modeling means is referred to for the two-dimensional position coordinates of the map display element. The altitude value of the corresponding two-dimensional position coordinate is read, and the display graphic data of the map display element represented by the three-dimensional coordinate including this altitude value is created.

According to a ninth aspect of the present invention, in the navigation system according to the eighth aspect, the position where the map data stored in the map data storage means is described by at least two-dimensional coordinates of a point group forming a road line element. Information and road type information indicating whether or not the corresponding road line element is an overpass or a tunnel, and the map element elevation determination means has two-dimensional position information of the road line element constituent point and the topographical shape. When determining the elevation value of the relevant point based on the model, if the relevant point is an internal constituent point of a series of road line elements that is an overpass or a tunnel, do not rely on the topographic shape model. , The elevation value of the internal constituent point is calculated from the already calculated elevation values of the two constituent points indicating the end points of the series of road line elements that are elevated or tunneled.

According to a tenth aspect of the present invention, in the navigation system according to the eighth or ninth aspect, the map data stored in the map data storage means is described by at least two-dimensional coordinates of a point group forming a road line element. Location information and road type information indicating whether or not the corresponding road line element is an overpass or a tunnel, and the map element elevation determination means has position information of the road line element constituent point and the topographical shape. When calculating the elevation value of the constituent point based on the elevation value of the data, the road line element corresponding to the constituent point is not an overpass or a tunnel, and the density of the constituent point is set by the terrain shape modeling means. If the density of the sampling points is smaller than the density of the sampled point group, a point that internally divides the road line element is added as a new constituent point and And it calculates the altitude value with reference to the terrain shape model by modeling means.

According to the invention of claim 11, in the navigation system according to claims 1 to 10, the map element elevation determining means is provided from the outside when creating graphic data for displaying roads, railways, water systems and facilities. Or, add a predetermined offset value to the original elevation value that is determined by itself and determine it as the coordinate value in the height direction of the road, railroad, water system and facility, and create the graphic data for display. It is a thing.

According to a twelfth aspect of the present invention, in the navigation system according to the eleventh aspect, the map element elevation determining means adds an offset value to the original elevation values of the road, railroad, water system and facility as the offset value of the road and The offset value used for the railway is set to a value larger than the offset values used for the water system and the facility.

[0022] The invention of claim 13, in claim 1 1-12 in the navigation system, said the map elements altitude determining means, as said offset value, than the offset value using the offset value used for the navigation route to the road and rail Is also a large value.

According to a fourteenth aspect of the present invention, in the navigation system of the first to thirteenth aspects, when the map element elevation determining means determines the elevation value of the graphic data indicating the current position of the vehicle, the topography modeling means is used. A figure obtained by adding a predetermined offset value to the elevation value determined based on the terrain shape model is determined as a coordinate value in the height direction of the current vehicle position, and the graphic data is created.

According to a fifteenth aspect of the present invention, in the navigation system according to the fourteenth aspect, the map element elevation determining means provides the road and rail as an offset value to be added to the elevation value of the graphic data indicating the current vehicle position. A value larger than the offset value used for this is used.

According to a sixteenth aspect of the present invention, in the navigation system of the first to fifteenth aspects, the map element elevation determining means is provided from the outside when creating the display graphic data of the point indicating the display position of the place name. , Or an original elevation value determined by itself, plus an offset value larger than the offset value set for the road, is determined as the coordinate value in the height direction of the point indicating the display position of the place name. Then, the display graphic data is created.

According to a seventeenth aspect of the present invention, in the navigation system according to the first to sixteenth aspects, the map element elevation determining means is provided from the outside when the point display graphic data indicating the display position of the place name is created. , Or an original elevation value determined by itself, plus an offset value that is a value that prevents any character in the character string displayed at the display position from being hidden by the terrain shape at the display position of the character. Is determined as the coordinate value in the height direction of the point indicating the display position of the place name, and the display graphic data is created.

The invention according to claim 18 is the navigation system according to any one of claims 1 to 17, wherein the drawing processing means is:
As a result of the perspective projection conversion by the coordinate conversion means, when a plurality of drawing elements among the drawing elements including the topographical shape and the map display element have an overlapping portion on the same straight line emitted from the viewpoint, the drawing elements are present farther from the viewpoint. When displaying the drawing element, the image display means displays only the portion excluding the overlapping portion.

According to a nineteenth aspect of the present invention, in the navigation system according to the first to seventeenth aspects, the drawing processing means includes:
As a result of the perspective projection conversion by the coordinate conversion means, when a plurality of drawing elements among the drawing elements including the topographical shape and the map display element have an overlapping portion on the same straight line emitted from the viewpoint, the drawing elements are present farther from the viewpoint. When the drawing element to be displayed is displayed, the overlapping portion is displayed on the image display means in a color different from that of other portions.

According to a twentieth aspect of the present invention, in the navigation system according to the nineteenth aspect, a color for displaying a portion other than the overlapping portion of the drawing elements and another drawing element having an overlapping portion with the drawing element are used as the different colors. A color obtained by mixing the displayed color with a predetermined ratio is used.

According to a twenty-first aspect of the invention, in the navigation system of the first to seventeenth aspects, the drawing processing means is
As a result of the perspective projection conversion by the coordinate conversion means, when a plurality of drawing elements among the drawing elements including the terrain shape and the map display element have an overlapping portion on the same straight line which originates from the viewpoint, the drawing element exists further from the viewpoint. When the drawing element to be performed is a line figure, the overlapping portion is displayed on the image display means by a broken line.

According to a twenty-second aspect of the present invention, in the navigation system of the first to twenty-first aspects, the drawing processing means is
When drawing the polyhedron shape showing the topographical shape, each surface of the polyhedron shape is drawn using a drawing color that changes according to the altitude.

According to a twenty-third aspect of the present invention, in the navigation system of the twenty-second aspect, when the drawing processing means draws the polyhedron shape indicating a terrain shape, each surface is drawn in a drawing color according to an altitude. At the same time, a ridge line group connecting the respective vertices is drawn.

According to a twenty-fourth aspect of the present invention, in the navigation system of the twenty-third aspect, among the ridge line groups connecting the respective vertices, only the ridge line group in a direction coinciding with the meridian and latitude directions is drawn.

A navigation system according to a twenty-fifth aspect of the present invention is a terrain data storage means for storing terrain shape data capable of giving elevation values to terrain plane coordinates, and a map display for displaying on a map such as roads and place names. Map data storage means for storing position information and auxiliary information of elements, display reference point position input means for inputting position coordinates and line-of-sight direction angle for determining position and direction of displayed map, and Display target area determining means for determining a target area (display target area) on the map displayed on the screen according to the display reference point position coordinates and the line-of-sight direction angle input from the display reference point etc. input means, and the display target. Sampling point groups having a predetermined density are set in the display target area determined by the area determining means, and the corresponding elevation value z is obtained with respect to the plane coordinates (x, y) of each sampling point. A polyhedral terrain shape model opened by reading from the terrain data storage means to generate a three-dimensional sampling point (x, y, z) group and connecting the three-dimensional sampling point group with ridge lines according to a predetermined rule. The elevation value of the display reference point is determined from the terrain shape modeling means that creates the display reference point and the display reference point position coordinates input from the display reference point input means and the terrain shape model obtained by the terrain shape modeling means. Perspective projection from the display reference point elevation determining means, the display reference point position coordinates and the line-of-sight direction angle input from the display reference point etc. input means, and the display reference point elevation value determined by the display reference point elevation determining means. Viewpoint coordinate determining means for determining the viewpoint coordinates for conversion, and reading a map display element corresponding to the display target area from the map data storage means. , Map element elevation determining means for determining the elevation value of each map display element based on the topographical shape model obtained by the topographical shape modeling means and creating display graphic data, and the viewpoint coordinate determining means Coordinate conversion means for performing perspective projection conversion between the terrain shape model and the map display element for which the elevation value has been determined based on the viewpoint coordinates determined by the display reference point and the viewing direction angle input from the input means. A topographical shape drawing processing means for drawing a polyhedron indicating the topographical shape perspective-transformed by the coordinate conversion means by overwriting from a surface farther from the viewpoint and outputting a stereoscopic map image; and the map element Map element altitude comparing means for comparing the altitude value of the display position of each map display element determined by the altitude determining means and the altitude value of the corresponding terrain shape,
Map element drawing processing means for drawing on the topographical shape by overwriting the topographical shape that is equal to or larger than the corresponding topographical shape of the map display element based on the comparison result of the map element elevation comparison means; An image display unit for combining and displaying the three-dimensional map image from the topographical shape drawing processing unit and the map element image from the map element drawing processing unit is provided.

According to a twenty-sixth aspect of the present invention, in the navigation system of the twenty-fifth aspect, the map element elevation comparing means sets the elevation value of the display position of each of the map display elements and the elevation value of the corresponding terrain shape in the terrain drawing color. The comparison is based on.

The invention of claim 27 is the same as claim 25 or 2.
In the navigation system of No. 6, when the map display element is a guide route, the map element drawing processing means draws with a drawing color different from that when the map display element is a normal road or with a different line type. It is a thing.

According to a twenty-eighth aspect of the present invention, in the navigation system according to the twenty-fifth to twenty-seventh aspects, when the map display element is a line figure, the map element elevation comparing means has elevation values at both end points of the line element, When the map display element is a surface figure, when the elevation values of all the vertices of the surface element are equal to or higher than the elevation values of the corresponding terrain shape, the map element drawing processing unit is instructed of the line element and the surface element. It outputs an overwrite command.

According to a twenty-ninth aspect of the invention, in the navigation system of the twenty-fifth to twenty-seventh aspects, when the map display element is a line figure, the map element elevation comparing means has an elevation of either end point of the line element. In the case where the map display element is a surface figure, and the elevation values of all the vertices of the surface element are smaller than the elevation values of the corresponding topographical shape, the map element drawing processing means applies the line element portion and the surface element. It is a command to overwrite a portion with a drawing color or a dotted line different from other portions.

A navigation system according to a thirtieth aspect of the present invention is a terrain data storage means for storing terrain shape data capable of giving elevation values to terrain plane coordinates, and a line figure such as a road, river or railroad map. Line graphic data storage means for storing position information and incidental information displayed above,
A place name and background data storage means for storing position information and incidental information for displaying a place name, a character string such as an icon and a pattern on a map, and a display reference point position for determining the position and direction of the displayed map. Display reference point input means for inputting coordinates and line-of-sight direction angle, and target area on the map displayed on the screen according to the display reference point position coordinates and line-of-sight direction angle input from the display reference point etc. input means ( Display target area determining means for determining a display target area), and a sampling point group having a predetermined density is set in the display target area determined by the display target area determining means, and set to plane coordinates (x, y) of each sampling point. Correspondingly, the corresponding elevation value z is read from the topographical data storage means and three-dimensional sampling points (x, y,
z) A group of terrain shape modeling means for creating a group and creating a terrain shape model of a polyhedron shape opened by connecting the group of three-dimensional sampling points with ridge lines according to a predetermined rule, and the input means such as the display reference points. Display reference point elevation determining means for determining the elevation value of the display reference point from the input display reference point position coordinates and the topographic shape model obtained by the topographic shape modeling means, and input from the display reference point etc. input means Viewpoint coordinate determining means for determining viewpoint coordinates of perspective projection conversion from the displayed reference point position coordinates and line-of-sight direction angles, and the display reference point elevation value determined by the display reference point elevation determining means; and the line graphic data. The line figure data corresponding to the display target area is read from the storage means, the place name, the place name from the background data storage means,
A map element that reads background data, determines the elevation value of each line figure and the display point of a place name, an icon, etc. based on the terrain shape model obtained by the terrain shape modeling means, and creates display figure data, if necessary. Altitude determining means, the topographical shape model based on the viewpoint coordinates determined by the viewpoint coordinate determining means and the line-of-sight direction angle input from the display reference point etc. inputting means, and the line figure in which the altitude value is determined, and Coordinate conversion means for performing perspective projection conversion of display figure data such as place names and icons, and drawing processing for drawing the data that has been perspective projection converted by the coordinate conversion means while performing hidden surface removal and outputting a stereoscopic map image. Means and a line for comparing the elevation value of the end point of each line element of the line graphic data determined by the map element elevation determination means with the elevation value of the corresponding terrain shape Based on the comparison result between the shape data altitude comparing means and the line figure data altitude comparing means, the altitude value of the end point of the line element of the line figure is equal to or higher than the corresponding topographical shape and the altitude value. Line graphic data drawing processing means for drawing by overwriting on the topographical shape, and image display means for displaying by combining the stereoscopic map image from the drawing processing means and the line graphic image from the line graphic data drawing processing means. Be prepared.

According to a thirty-first aspect of the present invention, in the navigation system of the thirtieth aspect, the line graphic data drawing processing means is different from the case where the line graphic is a normal road when the line graphic is a guide route. Different drawing colors or different line types.

The invention of claim 32 is the invention of claim 30 or 3.
In the navigation system according to the first aspect, the line graphic data altitude comparing means is configured to draw the line graphic data drawing processing means when the altitude values of both end points of each line element of the line graphic are equal to or higher than the altitude value of the corresponding topographical shape. Is output to the line element.

The invention of claim 33 is the invention of claim 30 or 3.
In the navigation system according to the first aspect, the line graphic data altitude comparing means is configured to draw the line graphic data drawing processing means when the altitude value of either end point of each line element of the line graphic is smaller than the altitude value of the corresponding topographical shape. To instruct the line element portion to be overwritten with a drawing color or a dotted line different from other portions.

A medium storing a navigation program according to a thirty-fourth aspect of the present invention determines a display target area based on position coordinates of a display reference point and line-of-sight direction angle data.
When, determines the row cormorants step modeling the terrain shape capture terrain shape data corresponding to the display target area, the elevation value of the display reference point from the position coordinates of the display reference point and said terrain shape model a step, and the position coordinates and viewing direction angle of the display reference point, and determining the viewpoint coordinates of the perspective projection transformation from said display reference point elevation, the map display element data corresponding to the display target area incorporation, The step of determining the elevation value of each map display element based on the terrain shape model to create display graphic data as necessary, the terrain shape model and the map display element of which the elevation value has been determined A step of performing perspective projection conversion based on viewpoint coordinates and the line-of-sight direction angle; and a step of generating a stereoscopic map image signal from the perspective projection converted data .
A navigation program that causes a computer to execute a step is stored.

A medium storing a navigation program according to a thirty-fifth aspect of the present invention includes a step for determining a display target area based on position coordinate of a display reference point and line-of-sight direction angle data.
And a sampling point group of a predetermined density is set in this display target area, and the corresponding elevation value z is taken in with respect to the plane coordinates (x, y) of each sampling point to obtain a three-dimensional sampling point (x, y, z) Generate a group, and connect the three-dimensional sampling point group with a ridgeline according to a predetermined rule to create an open polyhedral terrain shape model .
Step of the method, from the position coordinates of the display reference point and the terrain shape model to determine the elevation of the display reference point
Uptake and flop, the position coordinates and viewing direction angle of the display reference point, and determining the viewpoint coordinates of the perspective projection transformation from the altitude value of the display reference point, the map display element data corresponding to the display target area A step of deciding the elevation value of each map display element based on the terrain shape model to create graphic data for display as necessary, and the terrain shape model and the map display element having the elevation value determined. performing perspective projection transformation based on the viewpoint coordinates and said viewing direction angle
A step , a step of generating an image signal for drawing the polyhedron indicating the topographic shape that has been perspective-projected by overwriting from a surface farther to the viewpoint, and an elevation value of the display position of each of the map display elements. An image signal drawn by overwriting the topographical shape model for a map display element having a higher elevational value than the corresponding topographical shape based on the result of the comparison. The steps to generate and
This is a stored navigation program to be executed .

A medium storing a navigation program according to a thirty-sixth aspect of the present invention includes a step for determining a display target area based on position coordinate of a display reference point and line-of-sight direction angle data.
And a sampling point group of a predetermined density is set in this display target area, and the corresponding elevation value z is taken in with respect to the plane coordinates (x, y) of each sampling point to obtain a three-dimensional sampling point (x, y, z) Generate a group, and connect the three-dimensional sampling point group with a ridgeline according to a predetermined rule to create an open polyhedral terrain shape model .
Step of the method, from the position coordinates of the display reference point and the terrain shape model to determine the elevation of the display reference point
And a position coordinate and a line-of-sight direction angle of the display reference point, a step of determining the viewpoint coordinates of the perspective projection conversion from the elevation value of the display reference point, the line figure data corresponding to the display target area, In addition, a step of taking in the place name and background data, determining the elevation value of each line figure and place name, the display point of the icon, etc. based on the topographical shape model to create display figure data, and the viewpoint coordinates. A step of performing perspective projection conversion of the terrain shape model and the display figure data such as a place name and an icon for which the elevation value is determined based on the line-of-sight direction angle; and the perspective projection converted data is hidden. draw while running surface erasure, and generating a three-dimensional map image signals, the elevation of the terrain shape model corresponds with altitude values of the end points of the line elements of the line shapes with this And compare, and generating an image signal to be overwritten based on the comparison result, the larger than elevation of the terrain shape model corresponding the direction of elevation values of the end points of the line element of the line shapes to the terrain shape model To
The navigation program is stored in the computer .

In the navigation system according to the first aspect of the present invention, the topographical data capable of giving an elevation value to the topographical plane coordinates to the external storage means and the map display elements displayed on the map such as roads and place names. Map data that stores position information and incidental information is stored in advance.

When it becomes necessary to display a road map for route guidance, the display reference point position coordinates and the line-of-sight direction angle are input by the display reference point input means, so that the display target area determining means displays on the screen. The target area on the map to be displayed (display target area) is determined, and the terrain shape modeling means reads the terrain shape data corresponding to the display target area from the terrain data storage means to model the terrain shape.

Then, the display reference point elevation determining means determines the elevation value of the display reference point from the input display reference point position coordinates and the terrain shape model, and the viewpoint coordinate determining means determines the display reference point position coordinates and the line-of-sight direction. The viewpoint coordinates for perspective projection conversion are determined from the angle and the display reference point elevation value, and the map element elevation determination means further reads the map display element corresponding to the display target area from the map data storage means, and if necessary, the terrain. The elevation value of each map display element is determined based on the shape model, and display graphic data is created.

Then, the coordinate conversion means performs perspective projection conversion of the terrain shape model and the map display element for which the elevation value is determined based on the viewpoint coordinates and the line-of-sight direction angle, and the drawing processing means further performs this perspective projection conversion. A three-dimensional map image is generated from the data by a predetermined process, and this three-dimensional map image is displayed on the image display means.

As a result, in this navigation system, the road map can be displayed as a three-dimensional bird's-eye view, the road map can be displayed with a high sense of reality for the user, and the guide route and the current position can be intuitively grasped by the user. Will be able to.

In the navigation system according to the second aspect of the present invention, the drawing processing means draws the data, which has been perspective-projection-converted by the coordinate conversion means, while performing hidden surface removal, and outputs a stereoscopic map image, whereby the image display means is displayed. Display a three-dimensional bird's eye view of a road map.

In the navigation system according to the third aspect of the present invention, the drawing processing means draws the guide route in a drawing color or line type different from that of the normal road so that the guide route can be clearly distinguished from the normal road. To do.

In the navigation system according to the fourth aspect of the present invention, the terrain shape modeling means sets a sampling point group of a predetermined density in the display target area, which corresponds to the plane coordinates (x, y) of each sampling point. The elevation value z is read from the terrain data storage means to generate a three-dimensional sampling point (x, y, z) group, and the three-dimensional sampling point group is connected by an edge line according to a predetermined rule to form an open polyhedron shape. Create an approximate model of the terrain shape.

In the navigation system of the fifth aspect of the present invention, the terrain shape modeling means sets a sampling point group having a high distribution density in a partial region of the display target region which is close to the viewpoint coordinates, and a partial region far from the viewpoint coordinates. In (1), by setting a sampling point group having a low distribution density, it is possible to reduce the number of calculations and to perform high-speed drawing processing.

In the navigation system according to the sixth aspect of the present invention, the viewpoint coordinate determining means changes the elevation coordinate value of the viewpoint coordinates according to the display reference point elevation value determined by the display reference point determining means, so that the display target is always displayed. It enables a three-dimensional bird's-eye view display that looks down on the area.

In the navigation system of the seventh aspect of the present invention, the viewpoint coordinate determining means determines the elevation value of the viewpoint coordinates by adding a constant offset to the display reference point elevation value determined by the display reference point elevation determining means. By doing so, even if the elevation value of the display reference point changes, a stereoscopic bird's-eye view display can be performed with the elevation of the display reference point as the reference plane, and the problem that the viewpoint dives below the ground surface and correct display cannot be performed is avoided. be able to.

In the navigation system of the eighth aspect of the present invention, the map element altitude determining means uses the two-dimensional coordinates of the position information excluding the altitude of the map display element in which the map data stored in the map data storage means includes roads and place names. In the case of storing in the form of, the elevation value of the corresponding two-dimensional position coordinate is read with reference to the topographic shape model by the topographic shape modeling means for the two-dimensional position coordinate of the map display element, and the elevation value. The display graphic data of the map display element represented by the three-dimensional coordinates including is created.

In the navigation system according to the ninth aspect of the present invention, the map data stored in the map data storage means is at least the position information described by the two-dimensional coordinates of the point group forming the road line element and the corresponding road. The map element elevation determining means has road type information indicating whether or not the line element is an elevated structure or a tunnel, and the map element elevation determining means determines a road element element based on the two-dimensional position information of the road line element and the topographical shape model. When determining the elevation value, if the constituent point is an internal constituent point of a series of road line elements that is an elevated or tunnel, the end points of the series of road line elements that are an elevated or tunnel are indicated.
By calculating the elevation value of the internal constituent point from the already calculated elevation value of one constituent point, the road line element is displayed as if it is hidden in the mountain or the road crosses the sky as an overpass. You can do that, and your sense of reality will improve.

In the navigation system of the tenth aspect of the present invention, the map data stored in the map data storage means is at least the position information described by the two-dimensional coordinates of the point group forming the road line element and the corresponding road. It has road type information indicating whether the route element is an elevated road or a tunnel,
When the map element elevation determining means calculates the elevation value of the constituent point based on the position information of the road element constituent point and the elevation value of the topographical data, the road element corresponding to the constituent point is elevated or tunneled. , And if the density of the constituent points is smaller than the density of the sampling point group set by the terrain shape modeling means, add a point that internally divides this to the road line element as a new constituent point. By calculating the elevation value with reference to the terrain shape model for the added constituent points, the road that does not pass through the viaduct or tunnel penetrates the ground like a tunnel or floats above the sky like an viaduct. Instead, it always displays as if the road were running along the ground surface.

In the navigation system according to the eleventh aspect of the present invention, the map element elevation determining means is provided from the outside when creating the display graphic data of the line graphic or area graphic of roads, railways, water systems, facilities, etc. Or, by adding a predetermined offset value to the original elevation value that is determined by itself, it is determined as the coordinate value in the height direction of the line figure or area figure, and by creating the figure data for display, Even in areas where the terrain shape and the elevation values of these line and area figures match, the line and area figures are always displayed with priority over the terrain shape, and line and area figures with the same elevation value depending on the terrain shape. Make sure the display of does not fade.

In the navigation system of the twelfth aspect of the present invention, the map element elevation determining means uses the offset value used for the road and railway as the offset value to be added to the original elevation value of the road, railway, water system and facility. By setting a value larger than the offset value used for the facility, the line figure and area figure are always prioritized and displayed in the area where the elevation values of the terrain shape and line figure or area figure match. , Display important road and railway figures as a road map in preference to the equivalent figures of the water system and facilities, and the display of the road and railway figures with the same elevation value may be faint depending on the topography shape, water system, facilities, etc. So that there is no

In the navigation system according to the thirteenth aspect of the present invention, the map element elevation determining means uses a larger value for the guide route than the road and the railroad as an offset value to be added to the original elevation value of the map display element. Make it possible to clearly identify and draw a guide route from a normal road.

In the navigation system of the fourteenth aspect of the present invention, when the display reference point altitude determining means determines the altitude value of the graphic data indicating the current vehicle position, the display reference point altitude determining means determines it based on the topographical shape model by the topographical shape modeling means. By adding a predetermined offset value to the elevation value, it is determined as the coordinate value in the height direction of the current vehicle position, and by creating graphic data, the terrain shape and the elevation value are the same. Also, the current vehicle position is displayed with priority over the terrain shape so that the display of the current vehicle position is not blurred due to the terrain shape.

In the navigation system of the fifteenth aspect of the present invention, the map element elevation determining means has an offset value added to the elevation value of the graphic data indicating the current vehicle position, which is larger than the offset value used for the road and the railroad. By using the values, it is possible to prevent the display of the current vehicle position from being blurred by these line figures.

In the navigation system according to the sixteenth aspect of the present invention, the map element altitude determining means is given an external altitude or externally determined when the map element altitude determining means creates the graphic data for display of the point indicating the display position of the place name. The value added with an offset value larger than the offset value set for the road is determined as the coordinate value in the height direction of the point indicating the display position of the place name, and display graphic data is created. This prevents the character string of the place name, which is important information, from being blurred by the road figures having the same elevation value.

In the navigation system according to the seventeenth aspect of the present invention, when the map element altitude determining means creates the display graphic data of the point indicating the display position of the place name, the original altitude is given from the outside or is determined by itself. The display position of the place name is shown by adding to the value an offset value by which no character in the character string displayed at the display position is hidden by the terrain shape at the display position of the character. By determining the coordinate value in the height direction of the point and creating the graphic data for display, the entire character string of the place name can be displayed without being partially hidden by the gradient of the terrain shape.

In the navigation system of the eighteenth aspect of the present invention, the drawing processing means outputs a plurality of drawing elements from the viewpoint among the drawing elements including the topographical shape and the map display element as a result of the perspective projection conversion by the coordinate conversion means. When there is an overlapping portion on a straight line, by displaying only the portion excluding the overlapping portion on the image display means when displaying a drawing element existing farther from the viewpoint, a stereoscopic map close to the actual landscape Display.

In the navigation system according to the nineteenth aspect of the present invention, the drawing processing means, as a result of the perspective projection conversion by the coordinate conversion means, a plurality of drawing elements among the drawing elements including the terrain shape and the map display element are emitted from the viewpoint. When there is an overlapping portion on a straight line, when displaying a drawing element that is farther from the viewpoint, the overlapping portion is displayed in a different color from the other portions so that a part of the road is in front. Even if it is hidden by the terrain shape of, make it possible for the user to understand the state of the hidden part.

According to the twentieth aspect of the present invention, as the different colors used for the overlapping part in the eighteenth aspect, a color for displaying a part other than the overlapping part of the drawing elements and another drawing element having an overlapping part with the drawing element. Even if a part of the road is hidden by the topographical shape on the front side, the hidden part is made transparent by using the color mixed with the color for displaying Display as it can be seen.

In the navigation system according to the twenty-first aspect of the present invention, the drawing processing means outputs a plurality of drawing elements from the viewpoint among the drawing elements including the topographical shape and the map display element as a result of the perspective projection conversion by the coordinate conversion means. When there is an overlapping portion on a straight line, when the drawing element that is farther from the viewpoint is a line figure, the overlapping portion is displayed on the image display means by a broken line, so that a part of the road is in the foreground shape. Make it possible for the user to understand the state of the hidden part even if it is hidden in the.

In the navigation system according to the twenty-second aspect of the invention, the drawing processing means draws each surface of the polyhedron shape by using a drawing color that changes according to the altitude when drawing the polyhedron shape indicating the terrain shape. As a result, the display has a more three-dimensional effect.

In the navigation system of the twenty-third aspect of the present invention, when the drawing processing means draws the polyhedron shape indicating the topographical shape, each surface is drawn in a drawing color according to the altitude and each vertex is connected. By drawing the ridge lines, it is easy for the user to intuitively understand the undulations of the terrain.

In the navigation system of the twenty-fourth aspect of the present invention, when the drawing processing means draws a polyhedron shape indicating a topographical shape, each surface is drawn in a drawing color according to the altitude and each vertex is connected. By drawing only the ridge lines in the direction of the meridian line and the latitudinal line out of the ridge line group, it is easy for the user to intuitively understand the undulations of the terrain shape and the number of ridge line groups drawn. To reduce the complexity and prevent the user from easily recognizing the direction.

In the navigation system according to the twenty-fifth aspect of the present invention, the topographical shape data capable of giving the elevation value to the topographical plane coordinates to the external storage means and the map display elements to be displayed on the map such as roads and place names. Map data that stores position information and incidental information is stored in advance.

By inputting the display reference point position coordinates and the line-of-sight direction angle for determining the position and direction of the displayed map from the input means such as the display reference point, the display target area determining means determines the display reference point position. The target area (display target area) on the map displayed on the screen is determined according to the coordinates and the line-of-sight angle, and the terrain shape modeling means sets a sampling point group of a predetermined density in the display target area. The elevation value z corresponding to the plane coordinates (x, y) of the sampling points is read from the terrain data storage means to generate a three-dimensional sampling point (x, y, z) group, and this three-dimensional sampling point group is predetermined. Create a polyhedral shape terrain shape model that is opened by connecting with ridgelines according to the rule.

The display reference point elevation determining means determines the elevation value of the display reference point from the input display reference point position coordinates and the terrain shape model, and the viewpoint coordinate determining means determines the display reference point position coordinates and the line-of-sight direction. The viewpoint coordinates for perspective projection conversion are determined from the angle and the display reference point elevation value, and the map element elevation determination means further reads the map display element corresponding to the display target area from the map data storage means, and if necessary, the terrain. The elevation value of each map display element is determined based on the shape model, and display graphic data is created.

Then, the coordinate conversion means performs perspective projection conversion of the terrain shape model and the map display element for which the elevation value has been determined based on the viewpoint coordinates and the line-of-sight direction angle, and the terrain shape drawing processing means performs this perspective projection conversion. Draw a polyhedron showing the terrain shape that was created by overwriting from the back side to the viewpoint,
Output a 3D map image. At the same time, the map element elevation comparing means compares the elevation value of the display position of each map display element with the elevation value of the corresponding terrain shape, and based on the comparison result, the map element drawing processing means determines that the map display element is the map display element. Outputs a command for overwriting the terrain shape with respect to the terrain shape corresponding to or higher than the corresponding terrain shape. Then, the image display means overwrites the stereoscopic map image from the topographical shape drawing processing means with the map element image from the map element drawing processing means, and displays it.

As a result, in this navigation system, the road map can be displayed in a three-dimensional bird's-eye view, the road map can be displayed with a high sense of reality for the user, and the guide route and the current position can be intuitively grasped by the user. Will be able to. Moreover, in the case of this navigation system, since the hidden surface elimination processing is not performed, the load on the central processing unit for the arithmetic processing can be reduced, and high-speed drawing is possible.

In the navigation system of the twenty-sixth aspect of the present invention, the map element elevation comparing means compares the elevation value of the display position of each map display element with the elevation value of the corresponding terrain shape based on the terrain drawing color. Based on the comparison result,
The map element drawing processing means outputs the command for drawing the terrain shape by overwriting the terrain shape for which the terrain shape corresponding to the map display element is equal to or larger than the corresponding terrain shape, and the image created for display is used as it is. Therefore, the processing speed can be increased.

In the navigation system of the twenty-seventh aspect of the invention, the map element drawing processing means draws the map display element with a drawing color different from that of an ordinary road or with a different line type when the map display element is a guide route. This makes it possible to clearly identify the guide route.

In the navigation system according to the twenty-eighth aspect of the present invention, when the map element elevation comparing means has the map display element as a line figure, the elevation values at both end points of the line element and the map display element as a surface figure. , When the elevation values of all the vertices of the surface element are equal to or higher than the elevation values of the corresponding terrain shape, by outputting the command to overwrite the line element and the surface element to the map element drawing processing means, Even for line elements and surface elements having a density lower than the density of sampling points, the entire elements can be displayed without interruption without the process of adding internal constituent points to the line elements and surface elements.

In the navigation system according to the twenty-ninth aspect of the invention, when the map element elevation comparing means has a map display element which is a line figure such as a road, a river, or a railroad, the elevation value of either end point of the line element. Is smaller than the elevation value of the corresponding terrain shape, the map element drawing processing means is instructed to overwrite the line element portion with a drawing color or a dotted line different from that of other portions, so that a line figure such as a road is drawn. Even if a part is hidden by the topographical shape on the front side, the user can understand the state of the hidden part.

In the navigation system of the thirtieth aspect of the invention, the terrain data storage means stores terrain shape data capable of giving elevation values to the terrain plane coordinates,
Position information and incidental information for displaying line figures such as roads, rivers, and railways on the map are stored in the line figure data storage means, and character strings and patterns such as place names and icons are stored in the place name and background data storage means. The position information and incidental information displayed on the map are stored.

By inputting the display reference point position coordinates and the line-of-sight direction angle for determining the position and direction of the displayed map from the input means such as the display reference point, the display target area determining means determines the display reference point position. The target area (display target area) on the map displayed on the screen is determined according to the coordinates and the line-of-sight angle, and the terrain shape modeling means sets a sampling point group of a predetermined density in the display target area. The elevation value z corresponding to the plane coordinates (x, y) of the sampling points is read from the terrain data storage means to generate a three-dimensional sampling point (x, y, z) group, and this three-dimensional sampling point group is predetermined. Create a polyhedral shape terrain shape model that is opened by connecting with ridgelines according to the rule.

The display reference point elevation determining means determines the elevation value of the display reference point from the input display reference point position coordinates and the terrain shape model by the terrain shape modeling means, and the viewpoint coordinate determining means inputs. The viewpoint coordinates for perspective projection conversion are determined from the display reference point position coordinates and the line-of-sight direction angle, and the display reference point elevation value by the display reference point elevation determination means, and the map element elevation determination means displays the display target from the line graphic data storage means. The line figure data corresponding to the area is read, and the place name and the background data are read from the place name and background data storage means. Determine the elevation value and create graphic data for display.

Then, the coordinate conversion means, based on the viewpoint coordinates determined by the viewpoint coordinate determination means and the input line-of-sight direction angle, the terrain shape model by the terrain shape modeling means and the line figure and place name for which the elevation value has been determined. , And display graphic data such as icons are perspective-projection-converted, and the drawing processing unit further draws the perspective-projection-converted data while performing hidden surface removal to output a stereoscopic map image. At the same time, the line figure data elevation comparing means compares the elevation value of the end point of each line element of the line figure data with the elevation value of the corresponding topographical shape, and based on the comparison result, the line figure data drawing processing means Outputs a command to draw by overwriting the terrain shape when the elevation value at the end point of the line element is equal to or higher than the corresponding terrain shape. Then, the image display means displays the three-dimensional road map by superimposing the line figure image from the line figure data drawing processing means on the three-dimensional map image from the drawing processing means.

As a result, in this navigation system, the road map can be displayed in a three-dimensional bird's-eye view, the road map can be displayed with a high sense of reality for the user, and the guide route and the current position can be intuitively grasped by the user. Will be able to.

In the navigation system according to the thirty-first aspect of the present invention, the line graphic data drawing processing means draws a line color which is different from a normal road when the line graphic is a guide route,
Alternatively, the guide route can be clearly identified by drawing with different line types.

In the navigation system of the thirty-second aspect of the present invention, the line graphic data altitude comparing means is used when the altitude values of both end points of each line element of the line graphic are equal to or greater than the altitude values of the corresponding terrain shape. By outputting an overwriting command of the line element to the data drawing processing means, even a line element having a density smaller than the density of sampling points of the terrain shape is interrupted without adding the internal constituent points to the line element. The whole line element will be displayed without any.

In the navigation system of the thirty-third aspect of the present invention, the line graphic data altitude comparing means determines that the line graphic data is higher than one of the end points of the line elements of the line graphic which is smaller than the corresponding terrain shape. When a part of a line figure such as a road is hidden by the topographical shape on the front side by instructing the data drawing processing means to overwrite the line element part with a drawing color or a dotted line different from other parts But make sure the user can understand the hidden part.

In the medium storing the navigation program of the invention of claim 34, the navigation system of claim 1 can be realized by causing the central processing unit of the navigation system to execute the program.

The medium storing the navigation program of the thirty-fifth aspect of the invention can realize the navigation system of the twenty-fifth aspect by causing the central processing unit of the navigation system to execute the medium.

In the medium storing the navigation program of the thirty-sixth aspect of the invention, the navigation system of the thirtieth aspect can be realized by causing the central processing unit of the navigation system to execute the program.

[0094]

According to the first and second aspects of the present invention, the road map can be displayed in a three-dimensional bird's-eye view, and the road map can be displayed with a high sense of reality for the user, and the guide route and the current position can be used. It is possible to make the person intuitively grasp.

According to the third aspect of the present invention, the guide route can be displayed so that it can be clearly distinguished from the ordinary road.

According to the fourth aspect of the present invention, it is possible to create an approximate model of the terrain shape by the open polyhedron shape and display the terrain shape in three dimensions.

According to the fifth aspect of the invention, the number of calculations can be reduced and high-speed drawing of the terrain shape can be performed.

According to the invention of claim 6, it is possible to perform a natural stereoscopic bird's-eye view display in which the display target area is always looked down.

According to the invention of claim 7, even if the elevation value of the display reference point changes, a three-dimensional bird's-eye view display can be made with the elevation of the display reference point as the reference plane, and the viewpoint dives below the ground surface and is correct. It is possible to avoid problems such as being unable to display.

According to the eighth aspect of the present invention, in the hidden surface removal processing, the topographical shape and the map display element can be handled at the same time, and a three-dimensional road map can be created.

According to the invention of claim 9, a road passing through a tunnel can be displayed as if it is hidden in a mountain, and an elevated road can be displayed as if it crosses the sky. Reality is improved.

According to the tenth aspect of the present invention, it is possible to always display a road that does not cross overpass or pass through a tunnel as if the road is running along the ground surface.

According to the eleventh aspect of the present invention, the line figure or area figure is always displayed with priority over the terrain shape even in a portion where the elevation values of the terrain shape and the line figure or area figure match,
Depending on the terrain shape, it is possible to display line figures and surface figures having the same elevation value so as not to fade.

According to the twelfth aspect of the present invention, the line figure or area figure is always displayed with priority over the terrain shape even in a portion where the elevation value of the terrain shape and the elevation value of the line figure or area figure coincide with each other. Roads and railways, which are important as maps, are displayed by giving priority to those of water systems and facilities, and topographical shapes,
The shapes of roads and railways with the same altitude can be displayed so as not to be blurred by the shapes of the water system and facilities.

According to the thirteenth aspect of the present invention, the guide route can be clearly identified and drawn from the ordinary road.

According to the fourteenth aspect of the present invention, even if the terrain shape and the elevation value are the same, the current vehicle position is displayed with priority over the terrain shape, and the current vehicle position is displayed so as not to be faint depending on the terrain shape. can do.

According to the fifteenth aspect of the present invention, the current vehicle position can be displayed so as not to be blurred by the line graphics of the river and the railway.

According to the sixteenth aspect of the present invention, the character string of the place name, which is important information, can be displayed so as not to be blurred by the road figure having the same elevation value.

According to the seventeenth aspect of the invention, the whole character string of the place name can be displayed without being partially hidden by the gradient of the terrain shape.

According to the eighteenth aspect of the present invention, it is possible to display a three-dimensional map that is close to the actual landscape.

According to the invention of claim 19, even when a part of the road is hidden by the topographical shape on the front side, it is possible to display the hidden part so that the user can understand the state. .

According to the invention of claim 20, even when a part of the road is hidden by the topographical shape on the front side, the hidden part can be displayed so as to be visible through the topographical shape. The user can easily understand.

According to the twenty-first aspect of the invention, even when a part of the road is hidden by the topographical shape on the front side, the user can understand the state of the hidden part.

According to the twenty-second aspect of the present invention, it is possible to display a road map with a more three-dimensional effect.

According to the twenty-third aspect of the present invention, it is possible to display the undulating state of the terrain shape so that the user can intuitively understand it.

According to the twenty-fourth aspect of the present invention, it is easy for the user to intuitively understand how the terrain shape is undulated, and
It is possible to reduce the number of ridge lines to be drawn to prevent complication, and it is possible for the user to easily recognize the direction.

According to the twenty-fifth aspect of the present invention, the road map can be displayed in a three-dimensional bird's-eye view, the road map can be displayed with a high sense of reality for the user, and the guide route and the current position can be intuitively displayed to the user. In addition, since the hidden surface erasing process is not performed, the load on the central processing unit for arithmetic processing can be reduced, and high-speed drawing can be performed.

According to the twenty-sixth aspect of the present invention, since the elevation values are compared based on the drawing color, the image created for display can be used as it is and the processing speed can be increased.

According to the twenty-seventh aspect of the present invention, the guide route can be clearly identified and drawn from the ordinary road.

According to the twenty-eighth aspect of the present invention, even for line elements and plane elements having a density smaller than the density of sampling points of the terrain shape, the process of adding internal constituent points to the line elements and plane elements is not necessary. It can be displayed in its entirety without interruption.

According to the invention of claim 29, even if a part of a line figure such as a road is hidden by the topographical shape on the front side, the user can understand the state of the hidden part. Can be displayed.

According to the invention of claim 30, the road map can be displayed in a three-dimensional bird's-eye view, the road map can be displayed with a high sense of reality for the user, and the guide route, the current position, etc. can be intuitively displayed to the user. Can be grasped.

According to the thirty-first aspect of the invention, the guide route can be clearly identified and drawn from the ordinary road.

According to the thirty-second aspect of the invention, even with respect to the line elements having a density smaller than the density of the sampling points of the terrain shape, the line elements can be seamlessly processed without adding the internal constituent points to the line elements. The whole can be displayed.

According to the thirty-third aspect, even if a part of a line figure such as a road is hidden by the topographical shape on the front side, the user can understand the state of the hidden part. Can be displayed.

According to the invention of claim 34, the navigation system of claim 1 can be realized by using this.

According to the invention of claim 35, the navigation system of claim 25 can be realized by using this.

According to the invention of claim 36, the navigation system of claim 30 can be realized by using this.

[0129]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a system configuration according to one embodiment of the present invention. In terms of hardware, it is detected by a conventionally known GPS sensor or by self-contained navigation based on signals from a vehicle speed sensor, a direction sensor and a gyro sensor. Display reference point position input device 1 for calculating display reference point position coordinates and line-of-sight direction angle by designating a current position and traveling direction of a vehicle to be operated, or by designating an arbitrary point and traveling direction by a remote controller or a keyboard.
And an external storage device 2 for storing topographical data 2a composed of elevation value data of each point and map data 2b including information on roads and place names, and a central processing unit capable of high-speed arithmetic processing,
Arithmetic processing unit 3 including a computer having an internal storage device and an input / output interface, and this arithmetic processing unit 3
It is composed of an image display device 4 for displaying by an image signal output from.

As the terrain data 2a, elevation value data for each actual longitude / latitude coordinate point as shown in FIG. 2 (a) is stored as matrix table format data as shown in FIG. 2 (b). That is, a constant density in the horizontal direction,
For example, for each point (sampling point) arranged in a grid pattern at regular intervals in each of the meridian (y) and latitude (x) directions, the actual elevation value at that point is stored in a matrix table format.

Further, in the external storage device 2, the elevation value data in which such topographical data 2a is described for sampling points of a plurality of types of density are regarded as topographical data of different accuracy or different accuracy. Can be remembered. For example, every 100m, 500
The altitude data of the sampling points arranged every m and every 5 km are separately stored as the terrain data 2a of three kinds of accuracy. In this case, only one type of altitude data of 100 m sampling points, which is physically the highest accuracy, is stored as topographical data and used as it is according to the scale designation at the time of map display, or every 5 points exist. It is also possible to extract what is done as medium-precision terrain data, and to extract what is present at every 50 points as low-precision terrain data for use.

The data format of the topographical data 2a itself is not limited to this, and may be data represented by actual contour lines as shown in FIG. 3, and for example, z as latitude x and longitude y. It is also possible to register in the form of the curved surface equation given by = f (x, y), and the data form is not particularly limited.

The map data 2b stores display elements such as roads and place names displayed on the map, their position information, and if necessary, supplementary information such as attributes. For example,
For roads, the position coordinates of a series of points indicating each end point are displayed in the form of ridges or a group of continuous ridges, and the position coordinates of the road are used as position information for the road.
For surface graphics such as golf courses and station premises, the position coordinates of a series of points indicating each vertex and internal dividing points are displayed as polygons, and the position coordinates of the relevant water system and facility are used as position information for each point. The connection form is provided as an attribute.

That is, when the water system or facility as shown in FIG. 4A is defined by the vertices 1 to 5 and the internal points 6 and 7, small polygons (in this case, triangles, (Not limited to the above), that is, a set of vertices constituting the same, that is, a set of vertices shown in FIG. Therefore, when describing this water system or facility, 7
By drawing two adjacent small polygons (here, small triangles) according to the connection form that is an attribute, the entire surface figure such as a water system or facility is displayed.

In addition, regarding the place name and the road name, the coordinates of the position where the character string is displayed on the map are used as the position information, and the character string is provided as the attribute. Further, the attribute information added to the road link includes the type of the road (because it is necessary to change the display color depending on whether it is a highway, national road, or prefectural road) and form (whether it is a normal road, a tunnel, or an overpass). There is. These pieces of position information can be described and stored as two-dimensional coordinates corresponding to longitude and latitude, and can also be stored as three-dimensional coordinates including altitude value data. Furthermore, for the guide route to the destination obtained by the execution of another program by the central processing unit or the guide route set by the user himself, it is the guide route at each link (line element) of the corresponding road data. It is stored in the internal memory so that it can be distinguished from a normal road by setting a flag indicating that
For example, when road data is expressed by connecting short straight lines (line elements), the road data is (x0, y
0), (x1, y1), (x2, y2), (x3, y
3), ... Coordinates are designated to be connected by a straight line, but when such a road data is designated as a guide route, (x0, y0; 1), ( x1,
By setting flags such as y1; 1), (x2, y2; 1), ..., These are identified as line elements (links) of the guide route.

Explaining the configuration of various arithmetic processing functions executed by the arithmetic processing unit 3, the display target area determining section 3-1, the terrain shape modeling section 3-2, and the display reference point elevation determining section 3-
3, viewpoint coordinate determination unit 3-4, map element elevation determination unit 3-
5, a coordinate conversion unit 3-6 and a hidden surface removal drawing processing unit 3-7.

The display target area determining unit 3-1 sets the target area on the map to be displayed as the display reference point based on the coordinates of the display reference point and the line-of-sight direction input from the input device 1 such as the display reference point. It is the part that is determined on a horizontal plane virtually placed at altitude. The terrain shape modeling unit 3-2 sets a point group appropriately distributed in the display target area determined by the display target area determination unit 3-1 and corresponds to the plane coordinates (x, y) of each point. Read the elevation value z from the terrain data 2b (x,
y, z) three-dimensional data is generated, and this (x, y, z)
Is a vertex and connects each vertex with an appropriate ridgeline to create a polyhedron showing a topographical shape.

The display reference point elevation determining unit 3-3 obtains the display reference point x and y coordinate values (Px, Py) of the display reference point input from the input device 1 and the terrain shape modeling unit 3-2. Z coordinate value P in the height direction of the display reference point from the terrain shape
z is a part that is obtained by interpolation, and the viewpoint coordinate determination unit 3
-4 is a portion for obtaining the coordinates (Vx, Vy, Vz) of the viewpoint based on the position coordinates (Px, Py, Pz) of the display reference point obtained by the display reference point elevation determination unit 3-3, and is a map element. The altitude determining unit 3-5 reads the map element data in the display target area from the map data 2b, and if there is no altitude value, the corresponding altitude by interpolation by the same procedure as the calculation process of the display reference point altitude determining unit 3-3. This is a part for performing a process of adding a minute offset to the obtained altitude value in order to obtain the value and reduce the error of the topographical approximation and the blurring of the display due to the hidden surface removal described later.

The coordinate conversion section 3-6 is a section for obtaining two-dimensional coordinates (Sx, Sy) and depth coordinates Sz on the display screen by perspective projection conversion, and is a hidden surface removal drawing processing section 3-7.
Is a 3D map drawing signal with hidden surface removal enabled by comparing depth coordinates for each pixel and updating and drawing only those with a depth smaller than the already drawn pixels.
This is a part for outputting the three-dimensional map drawing signal to the image display device 4 to display a three-dimensional road map. Different drawing colors are assigned depending on the altitude value, and different drawing colors are assigned to roads, rivers, place names, etc. Further, the guide route is assigned a drawing color different from that of a normal road, and a particularly noticeable color such as red, yellow, or blue is assigned.

Next, the operation of the navigation system having the above configuration will be described with reference to the flowchart of FIG. The display processing of the three-dimensional map on the display screen of the image display device 4 by the arithmetic processing device 3 includes determination of the display target area, topography and map data every time the display reference point input from the input device 1 such as the display reference point is updated. Reading, determination of viewpoint coordinates,
Creation of display graphic data, coordinate conversion by perspective projection method,
It is executed by repeating a series of arithmetic processing such as drawing processing such as clipping.

When the position coordinates and the line-of-sight direction angle of the display reference points are input from the display reference point input device 1, the display target area determination unit 3-1 of the arithmetic processing device 3 causes the position coordinates of these display reference points. And the target area on the map displayed on the screen is determined based on the line-of-sight direction angle (step S301). Here, the display reference point is a representative point in the display screen for determining the position of the displayed map, and the line-of-sight direction angle is the azimuth angle of the orthogonal projection of the line of sight on the horizontal plane. is there. And to input this display reference point, for example,
In a vehicle-mounted navigation system, when displaying a map around the current position of the host vehicle, the GPS is used.
A vehicle position measuring device that measures and outputs the current position and the traveling direction by a sensor, a vehicle speed sensor, or a gyro sensor can be used as the input device 1 such as a display reference point. Alternatively, when the user designates an arbitrary point on the map and displays the map in the vicinity in the desired line-of-sight direction, a point designating means such as a remote controller or a keyboard as the display reference point output device 1. Can also be used.

The positional relationship between the viewpoint, the display reference point and the display target area will be described with reference to FIG. The display target area is specified by the two-dimensional coordinate system (x, y) corresponding to longitude and latitude regardless of the altitude value, and here, the horizontal plane having the same altitude as the display reference point is assumed to be the map plane. Further, if the height of the viewpoint coordinates is described by the offset h from the altitude value of the display reference point, the positional relationship shown in FIG. 6 is always established regardless of the altitude, and the conventional bird's-eye view display navigation system is used. Similarly, the display target area can be specified. That is, when the two-dimensional position coordinates (Px, Py) excluding the altitude of the display reference point and the line-of-sight direction angle φ are given from the display reference point input device 1, a predetermined viewpoint height offset h, a line-of-sight depression angle θ, The display target area can be obtained using the viewing angle β, the display reference point display position δ, and the like.

Next, as shown in FIG. 7, the terrain shape modeling unit 3-2 reads the terrain data in the range that can sufficiently cover the display target area obtained in step S301 from the external storage device 2 and models the terrain shape. Is performed (step S302). In this case, the display target area can be divided into several partial areas as in the case of multi-precision topographical data described later, and when different data is used in each area, it can be sufficiently covered for each partial area. The topographical data corresponding to the range will be read. When reading this topographical data, a part or all of the necessary data has been used for the previous display processing, and the arithmetic processing unit 3 has already been used.
If the data is stored in the internal storage device (not shown) of the above, the internal storage data is used as the data of the overlapping portion, and only the necessary data is read from the external storage device 2 to shorten the data transfer time. You can

In the terrain shape modeling process, the process shown in FIG.
As shown in, the sampling points included in a range that sufficiently covers the display target area determined by the display target area determination unit 3-1 (that is, (x, y) points at which topographical data is registered). Group) is set, the elevation value data z is read for each sampling point, a vertex is generated at the (x, y, z) coordinates for each sampling point as shown in FIG. As shown in (c), these vertices are connected to each other with adjacent latitudes and longitudes to generate a small quadrilateral (not necessarily a plane), and further, in each of these small quadrilaterals, for example, southeast -An open polyhedron shape is created by dividing it into two small triangles (which become a plane) by a diagonal line connecting the northwest vertices.

Here, as shown in FIG.
When modeling the terrain shape of the display target area using the terrain data of two different accuracies, the high accuracy terrain data is used in the area close to the viewpoint, and the low accuracy terrain data is used in the area far from the viewpoint. In the area where the two-dimensional topographic data are adjacent to each other, the real space points are connected so that all the faces forming the polyhedron are triangular.

Next, the display reference point elevation determining unit 3-3 determines the elevation value Pz of the display reference point (Px, Py) (step S303). For this, when the input device 1 such as the display reference point can input the altitude value Pz with sufficient accuracy, the value can be directly used. However, in the case of a system in which sufficient accuracy is not guaranteed or in a system in which the elevation value Pz itself is not measured, the two-dimensional position coordinates (Px, Py) of the display reference point and the previous step S302 are used.
The corresponding elevation value Pz is approximately calculated from the topographical data read in. This method will be described with reference to FIG.
First, among sampling points that give elevation values of topographical data, three points that are close to the display reference point (Px, Py) in the xy two-dimensional coordinate system are obtained. Next, as the points A, B, and C in the three-dimensional space in which the elevation values are given to these three points, the equation of the plane passing through these three points A, B, and C is obtained.
The z value obtained by substituting (x, y) = (Px, Py) into the equation of this plane is taken as the elevation value Pz of the display reference point. That is, the position vectors of the three spatial points A, B, C are A, B,
If C is given, Pz can be obtained by the following equation (1).

[0147]

[Equation 1] However, here

[Equation 2] And (Dx, Dy, Dz) represents a vector perpendicular to the plane defined by the three points A, B, and C.

Next, in the viewpoint coordinate determining unit 3-4, the height of the viewpoint coordinates is added by adding a predetermined viewpoint height offset h to the altitude value Pz of the display reference point thus obtained. Directional coordinate value Vz (= Pz + h)
Ask for. The xy coordinates (Vx, Vy) of the viewpoint are also obtained based on the line-of-sight direction angle and the like (step S304). That is, the viewpoint coordinates (Vx, Vy, Vz) are calculated based on the following equation (3) with reference to FIG.

[0149]

[Equation 3] Further, the map element altitude determination unit 3-5, based on the display target area determined by the display target area determination unit 3-1 from the map data 2b of the external storage device 2 to the road in the display target area,
Read map element data such as place name, and if there is no elevation value data, determine the corresponding elevation value by interpolation as in the calculation procedure for the display reference point elevation value, and perform the necessary offset processing of the elevation value. (Step S305).

That is, the map data 2b has the position coordinates of each map display element as position information. If this is described by the two-dimensional coordinates (x, y), it is not the case of the display reference point. Similarly, for each map display element, three sampling points including the position coordinates thereof are specified, and the elevation value data for each of these three sampling points is obtained from the topographical data read in step S302. ) The elevation value of each map display element is calculated based on the equation.

However, in this case, when the map display element is a road link, exception processing as shown in FIG. 10 is performed as necessary. It is assumed that there is a road link composed of dot sequences P1 to P8. When the elevation value interpolated from the terrain data is added to each constituent point and displayed together with the terrain shape, it becomes as shown in FIG. Since each elevation value is calculated so as to match the elevation value on the ground surface, the road link P1 as a whole
~ P8 will be along the ground surface. Here, if the portion corresponding to the dot sequence P2 to P7 is a tunnel on an actual road, the display of FIG.

Therefore, if the map data 2b is provided with the position information of the road link composing points and the data indicating whether the corresponding link as the attribute information corresponds to the tunnel or not, a series of link strings corresponding to the tunnel are provided. For the internal constituent points excluding both ends, first, the elevation values of both end points are calculated based on the topographical data, and then the elevation value of the internal constituent points is calculated using this result. That is, in the example of FIG. 10, it can be seen that P2 to P7 correspond to tunnels by examining the attribute information, and therefore the elevation values h2 and h7 for the end points P2 and P7 are calculated from the topographical data by the interpolation of equation (1). Then, the altitude value h of the internal constituent points P3, P4, P5, P6
For 3, h4, h5, and h6, for example, values obtained by proportionally distributing the altitude values h2 and h7 of the end points P2 and P7 in accordance with the distance from each point to both end points are applied. That is, the altitude value hi of each point in the tunnel is calculated by the following equation (4).

[0153]

[Equation 4] Here, djk is the total distance from Pj to Pk.
When the road link and the topographical shape are displayed based on the altitude value thus obtained, it is possible to display an indication that there is a tunnel between the road links P2 to P7 as shown in FIG. 10 (b). become able to.

On the contrary, since the number of constituent points that define the link is small despite the fact that there are undulations,
For road links that cannot express the actual undulations by simply connecting the points with straight lines, it is necessary to indicate the undulations of the road along the topographical shape. Therefore, processing for adding internal constituent points from the state of FIG. 10B and performing correction as shown in FIG. That is, as shown in FIG. 10B, when the road links are P1, P2, P7, and P8 (in this case,
The road link P2-P7 is a long straight road, and the internal constituent points P3, P4 are between these end points P2, P7.
P5 and P6 are added, the respective position coordinates (x, y) are obtained, and the same arithmetic processing as the altitude value calculation by interpolation of the above-mentioned display reference points is performed to perform the altitude values h3, h4, h of each point.
5 and h6 are calculated and as shown in FIG.
Is to be displayed along the surface of the earth as it is. When performing this process, the spacing between internal constituent points within a road link is internally divided between corresponding constituent points when the density is low compared to the sampling point density (that is, when the link is long). A new constituent point is added, and this is repeated recursively until all the corresponding constituent point densities become equal to or higher than the sampling point density, and thereafter, the elevation values of the points P3 to P6 based on the terrain data as usual. Is calculated.

The above correction processing is also applied to road links corresponding to elevated roads and road links not corresponding to elevated terrain shapes. That is, points P2-P in FIG.
7 is actually elevated, those points P2 to P7
When it is determined from the attributes of the respective constituent points that these road links are elevated, the constituent points P3 to P6 in the meantime are displayed in a form that crosses over the concave terrain. On the contrary, when there is one long road link between points P2 and P7 as shown in FIG. 10 (b) and the terrain shape between them is concave, the corresponding processing points are the same as the above processing. A new composing point that internally divides this is added between P2 and P7, and this is repeated recursively until all applicable composing point densities are equal to or higher than the sampling point density, and then based on the terrain data as usual. Then, the elevation value of each point P3 to P6 is calculated. When creating the graphic data indicating the map display element, the elevation value of each map display element obtained as described above, or originally the map data describes the position information of the map display element by three-dimensional coordinate values. In addition, the elevation value offset processing is performed by using a value obtained by adding a certain small amount of offset to the elevation value given as the height direction coordinate value as the display height direction coordinate value. For this height offset,
This will be described below.

Hidden surface removal processing is performed at the stage of drawing processing to be described later. For example, when a plane and a straight line existing on the plane are mathematically strictly drawn, the resolution of the surface screen, the rounding error of the computer, etc. Depending on the actual display, a straight line may be faint or partially hidden by a plane. In a 3D map, it is necessary to avoid this phenomenon when displaying roads, etc. on the ground surface (it may be preferable that such blurring occurs in the display of reference lines etc. described later), When creating graphic data of map display elements such as roads, the coordinate values in the height direction are slightly increased. Here, it is difficult to exactly obtain an appropriate offset value, and the calculation load of the central processing unit may become excessive. Therefore, in this embodiment, a stepwise value determined by the following procedure is applied.

As shown in FIG. 11, on the virtual map plane below the viewpoint height offset h from the viewpoint,
Consider a point P on this plane that is away from the viewpoint by d. Point P
If the point Q is obtained by shifting the height of the map by Δh to the information, in order to clearly display the point P originally on the virtual map plane in the display screen of the three-dimensional map, two points P and Q are displayed.
It suffices that the difference between the depth coordinates Pdepth and Qdepth obtained by perspective projection conversion based on a conversion formula described later becomes larger than the preset depth coordinate resolution.
Qdepth is given by the following equation (5).

[0158]

[Equation 5] Here, f and n are the upper limit value and the lower limit value of the depth coordinate for limiting the target space of the perspective projection transformation, and if the obtained depth coordinate does not exist within this range, it will not be displayed by clipping processing. . The value of Pdepth is
Since Δh = 0 is substituted in the above equation (5), the difference Δdepth between the two is as shown in the following equation (6).

[0159]

[Equation 6] On the other hand, assuming that the storage capacity of the register for storing the depth coordinates is M, that is, the depth coordinates are held by an integer value in the range of 0 to M-1, the range of the depth coordinates to be displayed is the above-mentioned. Considering that n is f, the resolution Res is as follows.

[0160]

[Equation 7] By solving for Δh in Δdepth> Res from these equations (6) and (7), the necessary condition for the height offset Δh can be obtained. Here, referring to the equation (6), the value of Δdepth becomes larger with respect to Δh as d is smaller, that is, the point P is closer to the viewpoint. Therefore, if Δh obtained for a certain d is uniformly used as the height offset, the condition is always satisfied in a range closer to the viewpoint than that. In fact, since the projected image is compressed in a range far from the viewpoint, the visibility is comparatively low, and the substantial effect of displaying the image with the height offset is small. Therefore, as a representative value of d, when the point P is at the intersection of the line of sight and the virtual map plane, that is, Δde at d = hcos θ
The following expression (8) is obtained by solving the conditional expression using the value of pth.

[0161]

[Equation 8] In the above derivation, the point P is assumed to exist on the virtual map plane, but the conditions differ if the elevation difference between the viewpoint and the point P changes. Further, since the ground surface which is a free-form surface is originally approximated by a polyhedron shape, the error of the elevation value between the road and the ground surface becomes larger. Therefore, the condition of the equation (8) is a very rough index, and it is actually necessary to set Δh to a larger value within this range.

Further, when the map display elements stored as the map data 2b include polygons representing water systems such as lakes and facilities such as golf courses in addition to road links, the same reason as above is given. Therefore, the elevation of the road must be offset higher than that of the offset of the water system and facility. Therefore,
For example, Δh as an offset of the elevation value of water system and facility
When 2 is used, 2Δh can be used as the offset of the elevation value of the road. Furthermore, with regard to the guide route, the offset 2Δh ′ is larger than that of the normal road.
(> 2Δh) should be set.

Although not a map display element stored as the map data 2b, for example, the display reference point corresponds to the current position of the own vehicle, and some figure (here, the vehicle current position mark) for indicating this is displayed. When creating and displaying, the offset of the elevation value is, for example, 2
By using Δh, it becomes possible to display the display reference point without being hidden by the water system or facility.
If h is used, the display reference point can be displayed without being hidden by the road.

In addition, the offset of the elevation value is also required when creating the graphic data for displaying the place name, that is, the character string. In the case of the place name, the position information stored in the map data 2b is the coordinates of the representative point that specifies the display position of the place name character string on the map. Therefore, offsetting the elevation value of the representative point itself above the ground surface or the like is not a direct purpose. However, for example, if the height coordinates of the representative point are set to match the lower side of the character string as shown in FIG. 12, in order to clearly display the character string up to the lower side, the ground surface or other display elements, etc. The elevation value must be corrected above.

Further, in the case of a place name, since the display character string has a length, if the ground surface has a slope as shown in FIG. 12, even if the representative point is above the ground surface, etc. There may be a case where a part of the character string is hidden by being buried in the ground surface or the like. In order to avoid this, in this embodiment, an appropriate offset is calculated according to the slope of the ground surface and the length of the character string to offset the altitude. in this case,
As shown in FIG. 13 (a), the length of the character string is constant everywhere on the display screen of the perspective projection view, so the corresponding length in the map space depends on the display position as shown in FIG. 13 (b). It will change. Therefore, as a representative value, the real space distance L corresponding to one character near the center of the display screen is obtained in advance, and the character string length is obtained by multiplying it by the number of characters n.
On the other hand, three topographical data sampling points near the representative point can be obtained from the two-dimensional coordinates of the representative point, and the maximum gradient Ψ can be obtained from the surface shape obtained from these points.

[0166]

[Equation 9] However, Dx, Dy, and Dz are values obtained by the equation (2).

Then, from these values, as shown in FIG. 14, an offset value Δhstr of the altitude value corresponding to the character string length of the graphic data indicating the place name is obtained.

[0168]

[Equation 10] However, if the number of characters is large or the gradient is large, Δh
Since str also becomes large and the character string may be displayed at a position extremely far from the place where the place name is originally supposed to be displayed, the upper limit of Δhstr is set in advance and the right side of equation (10) is If the upper limit is exceeded, the upper limit may be applied. On the contrary, when the gradient is small, Δhstr also becomes small and may be smaller than the altitude of the water system or the facility polygon offset by Δh, for example, so the lower limit value is set to 2Δh and the equation (10) The larger of the right side may be applied as the offset of the elevation value.

The flowchart of FIG. 15 shows in detail the map data reading and elevation value determining routine of step S305 executed by the above map element elevation determining unit 3-5. Explaining further based on the flowchart of FIG. 15, it is judged whether or not each of the map display elements already has an offset elevation value, and if such an elevation value is present, it is not necessary to recalculate, so return. To do. However, if there is a map display element that does not have the offset altitude value, the altitude value is offset in this routine (step S501).

First of all, for the target map display element, the arithmetic processing for interpolating the elevation value from the topographical data 2a is performed based on the equations (1) and (2) as in the case of the display reference point (step). S502). Then, it is determined whether the map display element is a road link, a water system, a facility, or a place name, and if it is a road link (step S503),
Determine whether it is a tunnel or an elevated road (step S504),
In the case of a tunnel or an overpass, the elevation value for each constituent point excluding both ends is calculated by interpolation from the elevation values at both end points based on the equation (4) (step S505). If it is not a tunnel or an overpass, on the contrary, it is judged whether or not there is sufficient constituent point density of road links (step S506). If the constituent point density is not sufficient, the link is internally divided to add constituent points,
Elevation values are interpolated from topographical data for each added component point to calculate.

In this way, if the processing of tunnels, overpasses, and the processing for increasing the density of constituent points is completed for road links as necessary, it is determined whether it is a guide route or an ordinary road for the elevation value of each constituent point. However, if it is a normal road, a preset offset Δh1 (for example, 2Δh described above) is added to offset the altitude value, and if it is a guide route, an offset Δh1 larger than that of a normal road is set. The altitude value is offset by ′ (> Δh1) (steps S509 and S51).
0).

Subsequently, if the map display element is a water system or a facility (step S511), the offset with the lowest offset Δh2 (also the above-mentioned Δh) is added to the altitude value (step S512).

Further, when the map display element is a place name (step S513), three terrain data sampling points in the vicinity are obtained from the two-dimensional plane coordinates of the representative point of the place name display, and the maximum is determined from the surface shape obtained from this. The gradient Ψ is obtained (step S514), the offset Δhstr corresponding to the character string length is obtained by the equation (10) (step S515), and the predetermined lower limit Δh3 is obtained.
And this offset Δhstr are compared, and the larger one is added to the elevation value of the representative point as an offset of the elevation value (step S516).

Further, when the map display element is the position of the own vehicle (step S517), the maximum offset Δh4 is added to the altitude value to offset it (step S518).

When the elevation value determination process is completed for all map display elements in this way, the coordinate conversion unit 3-6 executes the process of step S306 in the flowchart of FIG. 5, that is, the perspective projection conversion. In this perspective projection conversion, the perspective projection conversion is applied to the display graphic data such as the terrain shape, the map display element, and the display reference point,
Calculate the coordinate values on the display screen. When this conversion formula is expressed in the homogeneous coordinate system, the following formula (11) is obtained.

[0176]

[Equation 11] Here, the vector M is the map space coordinates (Mx, My, Mz) of the display graphic data to be converted, and 1 is added as the fourth component, and Vx, Vy, Vz are the viewpoint coordinates obtained by the equation (3). , Φ, θ are gaze direction angles and depression angles, f, n are upper and lower limit values that specify the clipping range in the depth coordinates, and Ds is a theoretical distance from the viewpoint to the display screen in pixel units.

Homogeneous coordinates T = obtained as a result of conversion
For (Tx, Ty, Tz, Tw), the two-dimensional coordinates (Sx, Sy) used for drawing are Sx = Tx / Tw, S
It is calculated by y = Ty / Tw. The depth coordinate is S
z = Tz / Tw.

After this perspective projection conversion processing, the hidden surface removal drawing processing unit 3-7 executes drawing processing including hidden surface removal and outputs it to the image display device 4 to display a stereoscopic bird's eye view of the road map. (Step S307).

In this processing, each drawing element after coordinate conversion is subjected to clipping processing or the like for drawing. Regarding the clipping in the x and y directions, based on the drawing range determined in advance by the size of the display screen, only those in which (Sx, Sy) are within this range are drawn, and other parts are not drawn. In the depth direction, n ≦ S
Only objects within the range of z ≦ f are to be drawn. Further, for pixels to be rendered, depth coordinates are compared for each pixel, and only those with a depth smaller than the already rendered pixels are updated and rendered, thereby rendering a three-dimensional map with hidden surface removal enabled. .

Each drawing element to be drawn is displayed using a predetermined drawing color. In this case, for example, with respect to the terrain shape, as shown in FIG. 16, it is drawn using a drawing color that continuously changes according to the altitude value. In this case, the correspondence between the altitude value and the drawing color to be assigned to the altitude value is determined in advance, and for example, the altitude value 0 to 50 m, 50 to 100 m, 100 to 200 m,
It is possible to draw as shown in FIG. 16 by giving the altitude value a width of 200 to 400 m and assigning the same color to the altitude values falling within the range.

Further, the surface of the polyhedron representing the terrain shape may be drawn, and at the same time the ridgeline thereof may be drawn. Then, in this case, as shown in FIG.
By drawing only those that correspond to the meridian direction (do not draw the dashed ridgelines), simply display the ridgelines clearly and 3
Not only can the effect of recognizing the topography as a dimensional shape be enhanced, but also the directions of north, south, east, and west can be clearly recognized on the three-dimensional map.

Each drawing element is executed by filling the corresponding pixel on the display screen with a predetermined drawing color for each pixel. When painting the pixel located at the screen coordinates (Sx, Sy), Corresponding depth coordinate Sz
Is stored in the register corresponding to (Sx, Sy),
Next, when trying to paint the same pixel (Sx, Sy) for another drawing element, the new depth coordinate Sz1 is compared with the value Sz0 already stored in the corresponding register, and Sz1
Is smaller, that is, only when the element to be drawn later is closer to the viewpoint, the drawing color of the corresponding pixel and the depth coordinate in the register are updated. If not, it is not updated. . This process is a method of hidden surface removal called Z buffering, and a pixel close to the viewpoint is always displayed for each pixel regardless of the order in which the drawing elements are drawn.

By enabling such Z buffering, as shown in FIG. 18, the drawing elements existing on the other side are displayed in such a manner that only the overlapping portions on the same line of sight are hidden and displayed according to the movement of the viewpoint. The visible range is gradually changed, and a more realistic expression can be made.

Furthermore, even if a drawing element (for example, a guide route) whose existence position is important as map information even if it is made invisible by hidden surface removal such as a road link is hidden as shown in FIG. 19 (a). The portions to be displayed may be displayed in different drawing colors as shown in FIG. 7B, or may be displayed by broken lines as shown in FIG. For this purpose, for example, after drawing the terrain shape and the road link by normal Z buffering, the comparison condition with the depth coordinates Sz0 and Sz1 is set in reverse, and the drawing color is changed for the road link farther from the viewpoint. It is realized by adding a method of redrawing by making it into a broken line or making it into a broken line. Note that the drawing color can be changed by, for example, using a color that is a mixture of the original drawing color of the road link and the drawing color of the already displayed terrain shape so that the road can be seen through the terrain shape. Such an effect can be given.

In this way, by executing the drawing processing up to step S307, one stereoscopic map screen can be created and displayed on the image display device 4, and further step S308.
At, it is determined whether or not to continue the map display, and if it continues, the procedure returns to step S301 and the procedure for creating and displaying the next screen is repeated. If the process is not continued, the above-described series of processing procedures are ended, and the process is moved to another process of the navigation system such as vehicle position detection and route calculation.

In this way, the map screen by the three-dimensional bird's-eye view according to the first embodiment of the present invention is as shown in FIG. 20, which is three-dimensionally expressed based on the elevation value data and map data of the actual topographical shape. It is possible to create and display a three-dimensional map with map display elements on topographical features, and to display a map that gives the user a strong sense of reality. It is possible to intuitively check the current position and the relationship with the surrounding environment. Can be recognized.

Next, FIG. 21 shows a second embodiment of the present invention.
~ It demonstrates based on FIG. The feature of the second embodiment is that, as in the first embodiment, the hidden surface is used for the data of the perspective projection conversion processing result executed by the coordinate conversion unit 3-6 in the arithmetic processing device 3. As in the case of the first embodiment, the erasing process is omitted, and instead of the viewpoint in the display target region, the process of drawing from the back side to the front side in the overwrite format is sequentially performed, as shown in FIG. The point is that it is possible to draw such a three-dimensional map.

The structure of the second embodiment will be described with reference to FIG. The hardware configuration is the same as that of the first embodiment shown in FIG.
The configuration of the arithmetic processing function in is changed.
The arithmetic processing device 3 includes a display target area determination unit 3-1 to a viewpoint coordinate determination unit 3-4 similar to those in the first embodiment. The map element elevation determining unit 3-5 ', the coordinate converting unit 3-6', the terrain shape drawing processing unit 3-8, the map element elevation comparing unit 3-9, and the map element are constituent elements different from those of the first embodiment. The drawing processing unit 3-10 is provided.

Of the new components, the map element elevation determining unit 3-5 'reads the map element data in the display target area from the map data 2b, and if the elevation value is not registered, the display reference point elevation determining unit. Similar to 3-3, this is a portion for calculating a corresponding elevation value by interpolation based on the equations (1) and (2) using three sampling points surrounding the representative point. Unlike, the elevation value offset is not set.

The coordinate transformation unit 3-6 'is a portion for obtaining the two-dimensional coordinates (Sx, Sy) on the display screen by perspective projection transformation, but unlike the first embodiment, the depth coordinate Sz.
Does not ask.

The terrain shape drawing processing unit 3-8 is a part for drawing a polyhedron indicating the terrain shape by sequentially overwriting from the surface toward the back. Even in the drawing process of the terrain shape, the drawing color is changed according to the altitude value. The map element elevation comparing unit 3-9, for each map display element, has the same elevation value and the same position on the screen only for each constituent point in the case of a road, water system, facility, etc., and for a representative point in the case of a place name. This is the part to compare with the terrain elevation value already drawn in. Here, if the elevation value of the map display element is not smaller, it is assumed to be in front of the ground surface. As shown in FIGS. 22A and 22B, when a map display element is to be drawn at the position of point P on the bird's-eye view, if the terrain shape is already drawn in the drawing color according to the elevation value. , The color of the pixel at the point P indicates the elevation value h1 of the point A closest to the viewpoint on the line of sight. Therefore, if the elevation value of the map element to be drawn is smaller than this, this map element will be present at the point B on the back side of the mountain in the figure, and will be hidden and invisible.

In the case of a road or the like, the map element drawing processing unit 3-10 draws the line elements as usual if both end points of both line elements are smaller than the ground surface, and if at least one of the end points is lower than the ground surface. Draw in different colors, draw in broken lines, or not (this should be set in advance), and configure this for water systems, facilities, etc. represented by area figures For each surface element (small polygon), if all vertices have an elevation value smaller than the ground surface, draw as usual, and if at least one vertex is lower than the ground surface, change the color or draw only the ridgeline. Is drawn with a broken line or is not drawn, and in the case of a place name etc., if the elevation value of the representative point is not small, it is drawn, and if it is small, it is not drawn and the instruction is output to the image display device 4. Department It is. That is, as shown in FIG. 23, since the terrain shape is modeled by approximating a polyhedron, even if the elevation value of the road is obtained for each constituent point, the road can be seen if the terrain shape between the constituent points is convex. Disappear. In the hidden surface removal processing executed in the first embodiment, in order to determine whether each pixel is visible or hidden, the road may partially disappear even if both end points are visible.
However, in the second embodiment, it is possible to simplify the arithmetic processing by determining whether or not to draw the entire line segment by determining whether the both end points are visible or hidden, and the road is interrupted at a place other than the tunnel. The phenomenon can be avoided.

The operation of the navigation system of the second embodiment having the above configuration will be described based on the flowcharts of FIGS. 24 and 25. The display target area determination unit 3-1 in the arithmetic processing device 3 determines the display target area (step S301), and the terrain shape modeling unit 3-.
The terrain data is read by 2 to model the terrain shape (step S302), and the display reference point elevation determining unit 3-3.
The display reference point elevation value is determined by (step S30
3) The procedure for determining the viewpoint coordinates by the viewpoint coordinate determining unit 3-4 (step S304) is the same as the procedure of the first embodiment shown in the flowchart of FIG.

After these processes, the map element elevation determining unit 3-5 'displays the display determined by the display target area determining unit 3-1 like the map element elevation determining unit 3-5 of the first embodiment. Map data 2b in the external storage device 2 based on the target area
The map element data such as roads and place names in the display target area is read from, and if there is no elevation value data, the corresponding elevation value is determined by interpolation similarly to the display reference point elevation value calculation procedure. However, in the case of this embodiment, FIG.
The elevation value offset processing in the flowchart of FIG. 5 is not performed (step S305 ').

Subsequently, the coordinate transformation unit 3-6 'executes perspective projection transformation in the same manner as the coordinate transformation unit 3-6 of the first embodiment, and the above-mentioned homogeneous coordinate T = obtained as a result of the transformation.
For (Tx, Ty, Tz, Tw), the two-dimensional coordinates (Sx, Sy) used for drawing are Sx = Tx / Tw, Sy
= Ty / Tw. However, in the case of this embodiment, the depth coordinate Sz is not obtained (step S30).
6 ').

Subsequently, the terrain shape drawing processing section 3-8 draws the polyhedron representing the terrain shape in the overwrite mode in order from the surface farthest from the viewpoint and displays it on the image display device 4. At this time, the drawing color is changed according to the altitude value (step S310).

Further, the map element elevation comparison unit 3-9 and the map element drawing processing unit 3-10 cooperate with each other to judge whether or not each map display element in the display target area is a place name or the like ( Step S311), if it is data including a representative point such as a place name and a character string, the elevation value of the representative point is compared with the elevation value of the terrain in the two-dimensional coordinates of the representative point (step S312), and the representative point If the elevation value of is equal to or higher than the elevation value of the terrain, the map element such as the character string assigned to the representative point is overwritten on the terrain shape (step S313).

If it is determined in step S311 that the map element is not a place name or the like, then it is determined whether the map element is a line figure such as a road, river, or railway (step S31).
4). In the case of a line figure, the elevation value of each of the end points 1 (one end point) and the end point 2 (the other end point) of each link is compared with the elevation value of the terrain of the corresponding two-dimensional coordinate (steps S315 and S316). If both end points are equal to or greater than the elevation value of the terrain, the map display element of this line figure is overwritten on the terrain display (step S317). However, if the elevation value of any of the end points is smaller than the elevation value of the terrain with the corresponding coordinates, draw a map element of a line figure connecting the end points 1 and 2 according to the preset option. A process is performed in which the color is changed or a broken line is used for overwriting, or no drawing is performed (step S31).
8).

Further, if it is determined in step S314 that the map element is not a line figure, it is a plane figure representing a lake, a river or a station facility with a wide basin, a golf course or other water system, a facility. It is determined whether or not all of the vertices 1 to n of the small polygon divided by the method shown in (4) are equal to or higher than the elevation value of the terrain (step S319-).
1 to 319-n), if any of the vertices 1 to n is equal to or larger than the elevation value of the terrain, the map display element of the surface figure is overwritten on the terrain display (step S3110).
However, if any of the vertices 1 to n of the small polygon of the surface figure is smaller than the elevation value of the terrain (step S319-
(If YES in any of 1 to S319-n)
In step S3111, the map element of the surface figure is changed in the drawing color, the ridge line is made into a broken line, and the map element is overwritten or not drawn (step S3111).

Then, the above steps S311 to S311
The process 1 is repeatedly executed for all map elements included in the display target area. Also, the display reference point mark such as the own vehicle position mark is displayed in accordance with the display of this map element (step S3112). As a result, a three-dimensional bird's-eye view display of a road map can be displayed on the screen of the image display device 4, as shown in FIG.

Further, in step S3113, it is determined whether or not to continue the map display. If it is continued, the process returns to step S301 and the procedure for creating and displaying the next screen is repeated. If the process is not continued, the above-described series of processing procedures are ended, and the process is moved to another process of the navigation system such as vehicle position detection and route calculation.

As described above, according to the second embodiment of the present invention, as in the case of the first embodiment, the terrain represented three-dimensionally based on the elevation data and map data of the actual terrain shape. It is possible to create and display a 3D map with map display elements on top of the shape, display a map that gives the user a sense of reality, and confirm the current position and intuitively recognize the relationship with the surrounding environment. Can be made.

Further, in the case of the second embodiment, since it is not necessary to perform the hidden surface erasing processing which imposes a heavy load on the central processing unit, the load on the central processing unit is reduced and the system is put to practical use. The performance required for the central processing unit to be mounted can be lowered, and the cost can be reduced accordingly. On the contrary, if the system is equipped with a high-performance central processing unit, the drawing processing can be speeded up accordingly. In addition, in the case of the second embodiment, it is possible to eliminate the discontinuity of the line figure of the road or the like due to the approximation error of the terrain shape, and it is possible to display it correctly.

Next, FIG. 26 shows a third embodiment of the present invention.
It will be described based on. The hardware configuration of the navigation system of the third embodiment is the same as that of the first embodiment shown in FIG.
21 is the same as that of the second embodiment shown in FIG. 21, except that the data type stored in the external storage device 2 and the configuration of the arithmetic processing function in the arithmetic processing device 3 are changed. Has been.

The external storage device 2 stores the terrain data 2a similar to that of the first embodiment, but the map data includes the representative point position information such as the terrain and icons, and the incidental information such as the place name character string, and the like. Place name and background data 2b1 for storing position information of map elements represented by surface figures such as water systems and facilities and incidental information such as connection forms, and position information of map elements represented by line figures such as roads, railways, rivers, etc. And additional information such as each attribute and the like are separately stored in the line figure data 2b2.

The arithmetic processing unit 3 has the same display target area determining section 3-1 to viewpoint coordinate determining section 3-4 as in the first embodiment.
Is equipped with. The map element altitude determination unit 3-5 ″ and the coordinate conversion unit 3-are provided as constituent elements different from those of the first embodiment.
6 ", a hidden surface removal drawing processing unit 3-7 ', a line graphic data altitude comparison unit 3-11 and a line graphic data drawing processing unit 3-12.

Among the new constituent elements, the map element elevation determining unit 3-5 ″ sets the map element data in the display target area to the place name of the external storage device 2, the background data 2b1 and the line graphic data 2.
By reading from b2, if the elevation value is not registered, by using the three sampling points surrounding the representative point as in the display reference point elevation determination unit 3-3, interpolation based on the equations (1) and (2) is performed. This is the part to calculate the corresponding elevation value. However, unlike the first embodiment, the offset of the elevation value is not set for the line graphic data.

The coordinate conversion unit 3-6 ″ obtains the two-dimensional coordinates (Sx, Sy) on the display screen by perspective projection conversion as in the first embodiment, and the map display elements other than the line graphic data 2b2. That is, the depth coordinate Sz is also obtained for the place name, background data 2b1 and topographical data 2a.

The hidden surface removal drawing processing unit 3-7 'validates the hidden surface removal for data other than line figure data, that is, topographical data, place names, and background data, by the same processing as in the first embodiment. This is a part to be displayed on the image display device 4.

The line graphic data altitude comparing section 3-11 uses the second
Similarly to the map element elevation comparing unit 3-9 of the embodiment, the elevation value of the end point of each line element of the line graphic data and the terrain elevation value already drawn at the same position on the screen (given by the drawing color) ) Is the part to compare with.

Then, the line graphic data drawing processing unit 3-12
Is similar to the map element drawing processing unit 3-10 of the second embodiment, each line element of the line graphic data is drawn as usual unless both end points have an elevation value smaller than the ground surface, and at least one end point is drawn. If is lower than the ground surface, it is a part in which the color is changed or the broken line is drawn, or no drawing is performed and nothing is output.

Next, the operation of the navigation system of the above-mentioned third embodiment will be described based on the flowchart of FIG. The display target area determination unit 3-1 of the arithmetic processing device 3 determines the display target area (step S301), and the terrain shape modeling unit 3-2 reads the terrain data to model the terrain shape (step S302). The procedure for determining the display reference point elevation value by the display reference point elevation determining unit 3-3 (step S303) and determining the viewpoint coordinates by the viewpoint coordinate determining unit 3-4 (step S304) is shown in the flowchart of FIG. The procedure is the same as that of the first embodiment.

After these processes, the map element elevation determining unit 3-5 ″ displays the display determined by the display target area determining unit 3-1 like the map element elevation determining unit 3-5 of the first embodiment. The map element data is stored in the external storage device 2 based on the target area.
The map element data such as roads, place names, etc. in the display target area is read from the place name, background data 2b1 and line figure data 2b2, and if there is no altitude value data, the same as the procedure for calculating the display reference point altitude value. Determine the corresponding elevation value by insertion. However, also in the case of the third embodiment, the offset processing of the elevation value in the flowchart of FIG. 15 is not performed on the line graphic data (step S30).
5 ″).

Subsequently, the coordinate transformation unit 3-6 ″ executes perspective projection transformation in the same manner as the coordinate transformation unit 3-6 of the first embodiment, and the above-mentioned homogeneous coordinates T = obtained as a result of the transformation.
For (Tx, Ty, Tz, Tw), the two-dimensional coordinates (Sx, Sy) used for drawing are Sx = Tx / Tw, Sy
= Ty / Tw, and depth coordinates Sz (= Tz / Tw) are obtained for data other than line figure data (that is, topographic data, place names, background data) (step S306 ″).

Subsequently, the hidden surface removal drawing processing unit 3-7 '
For data other than line figure data such as topographical data, place names, and background data, hidden surface removal is enabled and displayed on the image display device 4 in the same manner as the hidden surface removal drawing processing unit 3-7 of the first embodiment ( Step S307 ').

Furthermore, the line figure data altitude comparing section 3
-11 and the line graphic data drawing processing unit 3-12 cooperate with each other,
End point 1 of each link for each line figure in the display area
The elevation value of each of the end point (one end point) and the end point 2 (the other end point) is compared with the elevation value of the terrain having the corresponding two-dimensional coordinates (steps S320 to S322), and the elevation value of the terrain having both end points is the respective coordinates. If it is larger than this, this line figure is overwritten on the topography, place name, icon, etc. (step S323). However, if the elevation value of any of the end points is smaller than the elevation value of the terrain with the corresponding coordinates, change the drawing color of the map element of the line figure connecting the end points according to the preset option. , Or a broken line is overwritten or not drawn (step S324). And the above steps S320 to S
The processing of 324 is repeatedly executed for all the line figures included in the display target area (step S325).

As a result, the stereoscopic bird's-eye view display of the road map can be displayed on the screen of the image display device 4, as shown in FIG.

[0218] Further, in step S326, it is determined whether or not the map display is to be continued.
Returning to step 301, the procedure for creating and displaying the next screen is repeated. If the process is not continued, the above-described series of processing procedures are ended, and the process is moved to another process of the navigation system such as vehicle position detection and route calculation.

As described above, according to the third embodiment of the present invention, as in the first embodiment, the terrain represented three-dimensionally based on the elevation value data and map data of the actual terrain shape. It is possible to create and display a 3D map with map display elements on top of the shape, display a map that gives the user a strong sense of reality, and intuitively check the current position and the relationship with the surrounding environment. Can be recognized.

In addition, in the case of the third embodiment, since line graphics such as roads can be seen and hidden only by the end points, it is possible to eliminate breaks due to the approximation error of the terrain shape, and to hide hidden areas such as place names and icons. Since the drawing process is performed by erasing, even if the representative point is hidden, it can be partially displayed, and the stereoscopic effect can be further enhanced.

Although the navigation systems have been described in the above first to third embodiments, various processing function units incorporated in the arithmetic processing unit 3 of these navigation systems are converted into software programs into internal storage devices. Alternatively, it may be incorporated into or stored in an appropriate storage medium as an application software program, and may be read into an internal storage device of the arithmetic processing unit 3 and used when used.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a terrain data structure in the above embodiment.

FIG. 3 is an explanatory diagram showing another example of a terrain data structure in the above embodiment.

FIG. 4 is an explanatory diagram showing a data structure of a surface figure in the above embodiment.

FIG. 5 is a flowchart of map display processing according to the above embodiment.

FIG. 6 is an explanatory diagram showing a principle of determining a viewpoint and a display target area in the above embodiment.

FIG. 7 is an explanatory diagram showing modeling of a terrain shape in the above embodiment.

FIG. 8 is an explanatory diagram showing another example of a method of determining sampling points in a display target area in the above embodiment.

FIG. 9 is an explanatory diagram showing a method of calculating an elevation value of a display reference point in the above embodiment.

FIG. 10 is an explanatory diagram showing the principle of the interpolation processing of the elevation value of the road in the tunnel and the addition processing of the road constituent points according to the terrain shape in the above embodiment.

FIG. 11 is an explanatory diagram showing the principle of setting the offset of the map display element in the above embodiment.

FIG. 12 is an explanatory diagram showing a hidden phenomenon of a character string of a place name in the above embodiment.

FIG. 13 is an explanatory diagram showing a relative distance and an absolute distance of a place name character width on a map in the above embodiment.

FIG. 14 is an explanatory diagram showing an example of setting an offset for a character string of a place name in the above embodiment.

FIG. 15 is a flowchart of altitude value determination processing in the above embodiment.

FIG. 16 is an explanatory diagram showing a display example of a polyhedron shape created based on the terrain data in the above embodiment.

FIG. 17 is an explanatory diagram showing another display example of the polyhedral shape created based on the terrain data in the above embodiment.

FIG. 18 is an explanatory diagram showing a change in place name display due to movement of a viewpoint in the above embodiment.

FIG. 19 is an explanatory diagram showing a display example of a hidden portion of a road in the above embodiment.

FIG. 20 is an explanatory diagram showing a stereoscopic bird's-eye view display example of a road map according to the above embodiment.

FIG. 21 is a functional block diagram of the second embodiment of the present invention.

FIG. 22 is an explanatory diagram showing the principle of stereoscopic bird's-eye view display in the above embodiment.

FIG. 23 is an explanatory diagram showing a display process of a hidden portion of a road in the above embodiment.

FIG. 24 is a flowchart of the first stage of the map display process according to the above embodiment.

FIG. 25 is a flowchart of a latter stage of the map display process according to the above embodiment.

FIG. 26 is a functional block diagram of a third embodiment of the present invention.

FIG. 27 is a flowchart of map display processing according to the above embodiment.

FIG. 28 is an explanatory view showing a bird's-eye view display of a conventional road map.

[Explanation of symbols]

1 Display reference point input device 2 External storage device 2a Topographic data 2b Map data 2b1 Place name, background data 2b2 line figure data 3 arithmetic processing unit 4 Image display device 3-1 Display target area determination unit 3-2 Terrain shape modeling section 3-3 Display reference point altitude determination unit 3-4 Viewpoint coordinate determination unit 3-5, 3-5 ', 3-5 "Map element elevation determination unit 3-6, 3-6 ', 3-6 "coordinate conversion unit 3-7, 3-7 'Hidden surface removal drawing processing unit 3-8 Terrain shape drawing processing unit 3-9 Map element elevation comparison section 3-10 Map element drawing processor 3-11 Line figure data altitude comparison section 3-12 Line graphic data drawing processing unit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Oizumi 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Norimasa Kishi 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. In-house (56) Reference JP-A-9-138136 (JP, A) JP-A-5-203457 (JP, A) JP-A-5-101163 (JP, A) JP-A-6-195436 (JP, A) ) JP-A-6-36013 (JP, A) JP-A-8-44996 (JP, A) JP-A-7-249114 (JP, A) JP-A-5-120410 (JP, A) JP-A-3- 75682 (JP, A) JP 5-27676 (JP, A) JP 7-220055 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G09B 29/00-29 / 14 G01C 21/00 G06T 17/40 G06T 17/50 G08G 1/0969

Claims (36)

(57) [Claims] 1. A terrain data storage means for storing terrain shape data capable of giving elevation values to terrain plane coordinates, and position information and incidental information of map display elements such as roads and place names displayed on a map. Map data storage means to be stored, display reference point position coordinates for determining the position and direction of the displayed map, display reference point etc. input means, and input from the display reference point etc. input means Display target area determining means for determining the target area (display target area) on the map displayed on the screen according to the displayed reference point position coordinates and the line-of-sight direction angle, and the display determined by the display target area determining means Terrain shape modeling means for reading terrain shape data corresponding to the target area from the terrain data storage means and modeling the terrain shape using the terrain shape data Display reference point elevation determining means for determining the elevation value of the display reference point from the display reference point position coordinates input from the display reference point etc. input means and the terrain shape model obtained by the terrain shape modeling means; View point coordinates for determining the view point coordinates of perspective projection conversion from the display reference point position coordinates and line-of-sight direction angles input from the display reference point etc. inputting means, and the display reference point elevation value determined by the display reference point elevation determining means. Determining means, reading the map display element corresponding to the display target area from the map data storage means, and if necessary, the elevation value of each map display element based on the terrain shape model obtained by the terrain shape modeling means. Map element elevation determining means for determining and creating display graphic data, viewpoint coordinates determined by the viewpoint coordinate determining means, and the display base And coordinate conversion means and a map display elements that is determined of the elevation and the terrain shape model to perspective transformation based on the visual line direction angle inputted from the point such as the input means,
A navigation system comprising: drawing processing means for generating a stereoscopic map image from the data perspective-transformed by the coordinate conversion means; and image display means for displaying the stereoscopic map image. 2. The navigation system according to claim 1, wherein the drawing processing unit generates a stereoscopic map image while performing hidden surface removal on the data that has been perspective-projected by the coordinate conversion unit. 3. The navigation system according to claim 1, wherein the drawing processing unit draws the guide route in a drawing color or line type different from that of an ordinary road. 4. The topographical shape modeling means sets a sampling point group having a predetermined density in the display target area determined by the display target area determining means, and with respect to the plane coordinates (x, y) of each sampling point. The corresponding elevation value z is read from the topographical data storage means to generate a group of three-dimensional sampling points (x, y, z), and the group of three-dimensional sampling points is connected by a ridge line according to a predetermined rule to open. The navigation system according to claim 1, wherein a terrain shape model having a polyhedron shape is created. 5. The terrain shape modeling means sets a sampling point group having a high distribution density in a partial area of the display target area near the viewpoint coordinates, and sets a sampling density group in a partial area far from the viewpoint coordinates. The navigation system according to claim 4, wherein a low sampling point group is set. 6. The viewpoint coordinate determining means changes the altitude coordinate value of the viewpoint coordinates according to the display reference point altitude value determined by the display reference point altitude determining means. Navigation system according to any one. 7. The viewpoint coordinate determining means determines the elevation value of the viewpoint coordinates by adding a constant offset to the display reference point elevation value determined by the display reference point elevation determining means. The navigation system according to claim 6. 8. The map element elevation determining means stores position information in the form of two-dimensional coordinates excluding the elevation of a map display element in which the map data stored in the map data storage means includes roads and place names. In the case of, the elevation value of the corresponding two-dimensional position coordinate is read with reference to the two-dimensional position coordinate of the map display element, by referring to the topographic shape model modeled by the topographic shape modeling means. The navigation system according to any one of claims 1 to 7, wherein display graphic data of a map display element represented by three-dimensional coordinates including is created. 9. The map data stored in the map data storage means includes position information described in at least two-dimensional coordinates of a point group forming a road line element, and the corresponding road line element is an elevated road or a tunnel. Road type information indicating whether or not there is, and the map element elevation determining means is 2 of the road line element composing points.
When determining the elevation value of the constituent point based on the dimensional position information and the terrain shape model, if the constituent point is an internal constituent point of a series of road line elements that are elevated or tunnels, It is characterized in that the elevation value of the internal constituent point is calculated from the already calculated elevation values of the two constituent points indicating the end points of a series of road line elements that are elevated or tunnels, based on the terrain shape model. The navigation system according to claim 8. 10. The map data stored in the map data storage means includes position information described in at least two-dimensional coordinates of a point group that constitutes a road line element, and the corresponding road line element is an elevated road or a tunnel. Road type information indicating whether or not there is, the map element elevation determining means, based on the position information of the road line element configuration point and the elevation value of the topographical shape data, the elevation value of the configuration point. When calculating, when the road line element corresponding to the constituent point is not an overpass or a tunnel and the density of the constituent point is smaller than the density of the sampling point group set by the topographical shape modeling means, the road line element A point that internally divides this with respect to the prime is added as a new constituent point,
10. The navigation system according to claim 8, wherein an elevation value is calculated for the added constituent points by referring to the terrain shape model by the terrain shape modeling means. 11. The map element elevation determining means is a road,
When creating graphic data for display of railways, water systems, and facilities, add a predetermined offset value to the original elevation value given from the outside or determined by itself, the road, railroad, water system 11. The navigation system according to any one of claims 1 to 10, wherein the display system determines the coordinate value in the height direction of the facility and creates display graphic data. 12. The map element elevation determining means uses an offset value used for the road and railway as an offset value to be added to the original elevation value of the road, railway, water system and facility. The navigation system according to claim 11, wherein the navigation system has a value larger than the value. Wherein said map elements altitude determining means as the offset value, the offset value used for the induction path, characterized in that a value larger than the offset value used for the road and rail claims 1 1 to 12 Navigation system according to any one of. 14. The map element altitude determining means, when determining the altitude value of the graphic data indicating the current vehicle position, is based on the altitude value determined based on the terrain shape model by the terrain shape modeling means in advance. The navigation system according to any one of claims 1 to 13, wherein the figure data is created by determining a coordinate value in the height direction of the current vehicle position to which a predetermined offset value is added. 15. The map element altitude determination means uses a value larger than an offset value used for the road and railway as an offset value added to the altitude value of the graphic data indicating the current vehicle position. The navigation system according to claim 14, wherein the navigation system is a system. 16. The map element elevation determining means, when creating display graphic data of a point indicating a display position of a place name,
The original elevation value given from the outside or determined by itself, plus an offset value larger than the offset value set for the road, in the height direction of the point indicating the display position of the place name. 16. The coordinate value is determined and the display graphic data is created.
Navigation system according to any one of. 17. The map element elevation determining means, when creating the display graphic data of the point indicating the display position of the place name,
An offset value that is a value that does not hide any character of the character string displayed at the display position from the original elevation value given externally or determined by itself, by the topographic shape at the display position of the character. The navigation system according to any one of claims 1 to 16, characterized in that the coordinate value in the height direction of the point indicating the display position of the place name is determined to add the display graphic data. 18. The drawing processing means, as a result of the perspective projection conversion by the coordinate conversion means, a plurality of drawing elements among the drawing elements including the terrain shape and the map display element overlap each other on the same straight line emitted from the viewpoint. 18. When displaying, the display unit displays only a portion excluding the overlapping portion when displaying a drawing element existing farther from the viewpoint, according to any one of claims 1 to 17. Navigation system. 19. The drawing processing means, as a result of perspective projection conversion by the coordinate conversion means, a plurality of drawing elements among the drawing elements including a topographical shape and a map display element overlapped on the same straight line originating from the viewpoint. 18. When any one of the above items is included, the overlapping portion is displayed in a color different from that of the other portion on the image display means when a drawing element existing farther from the viewpoint is displayed. Navigation system described in. 20. As the different color, a color for displaying a portion other than an overlapping portion of the drawing element and a color for displaying another drawing element having an overlapping portion with the drawing element are mixed based on a predetermined ratio. 20. The navigation system according to claim 19, wherein the selected color is used. 21. As a result of the perspective projection conversion by the coordinate conversion unit, the drawing processing unit is a portion where a plurality of drawing elements among the drawing elements including a topographical shape and a map display element overlap on the same straight line emitted from the viewpoint. 18. When the drawing element is present, when the drawing element existing farther from the viewpoint is a line figure, the overlapping portion is displayed on the image display means by a broken line. Navigation system. 22. The drawing processing means draws each surface of the polyhedron shape using a drawing color that changes according to an altitude when drawing the polyhedron shape indicating a topographical shape. Item 22. The navigation system according to any one of items 1 to 21. 23. The drawing processing means draws each surface in a drawing color corresponding to an elevation and draws a ridge line group connecting each of the vertices when drawing the polyhedral shape showing a topographical shape. The navigation system according to claim 22, wherein: 24. The navigation system according to claim 23, wherein among the ridge line groups connecting the respective vertices, only the ridge line group having a direction coinciding with a meridian line and a parallel line direction is drawn. 25. Topographical data storage means for storing topographical shape data capable of giving elevation values to topographical plane coordinates, and position information and incidental information of map display elements displayed on a map such as roads and place names. Map data storage means to be stored, display reference point position coordinates for determining the position and direction of the displayed map, display reference point etc. input means, and input from the display reference point etc. input means Display target area determining means for determining a target area (display target area) on the map displayed on the screen in accordance with the displayed reference point position coordinates and the line-of-sight direction angle, and the display target determined by the display target area determining means A sampling point group having a predetermined density is set in the area, and the corresponding elevation value z with respect to the plane coordinates (x, y) of each sampling point is read from the topographical data storage means to obtain the third order. Terrain shape modeling means for generating a sampling point (x, y, z) group, and creating an open polyhedral shape terrain shape model by connecting the three-dimensional sampling point group with a ridge line according to a predetermined rule; Display reference point elevation determining means for determining the elevation value of the display reference point from the display reference point position coordinates input from the display reference point etc. input means and the terrain shape model obtained by the terrain shape modeling means; Point-of-view coordinate determination for determining the point-of-view coordinate of perspective projection conversion from the display-reference-point position coordinates and the line-of-sight direction angle input from the reference-point input means, and the display reference-point elevation value determined by the display-reference-point elevation determination means. Means, and a map display element corresponding to the display target area from the map data storage means, and if necessary, the terrain shape modeling Map element elevation determining means for determining the elevation value of each map display element based on the terrain shape model obtained by the means, and creating map data for display; viewpoint coordinates determined by the viewpoint coordinate determining means and the display; Coordinate conversion means for performing perspective projection conversion between the terrain shape model and the map display element for which the elevation value has been determined based on the line-of-sight direction angle input from reference point input means, and perspective projection conversion by the coordinate conversion means. A polyhedron showing the formed topographical shape by overwriting from the surface farther from the viewpoint and outputting a three-dimensional map image; and a map display determined by the map element elevation determining means. Map element elevation comparison means for comparing the elevation value of the display position of each element and the elevation value of the corresponding terrain shape, and the comparison result of the map element elevation comparison means On the basis of the map display element, a map element drawing processing unit that draws by overwriting on the terrain shape with respect to the terrain shape corresponding to or higher than the corresponding terrain shape; And a map element image from the map element drawing processing means, and an image display means for displaying the synthesized image. 26. The map element elevation comparing means compares the elevation value of the display position of each of the map display elements with the elevation value of the corresponding terrain shape based on the terrain drawing color. Navigation system described in. 27. The map element drawing processing means draws when the map display element is a guide route, a drawing color different from that when the map display element is an ordinary road or a different line type. 27. The navigation system according to claim 25 or 26. 28. The map element elevation comparing means, when the map display element is a line figure, the elevation values at both end points of the line element, and when the map display element is an area figure, the map element elevation 28. When the elevation values of all the vertices are equal to or greater than the elevation values of the corresponding terrain shape, the command for overwriting the line element or the surface element is output to the map element drawing processing means. Navigation system according to any one of. 29. When the map display element is a line figure such as a road, a river, or a railroad, the map element elevation comparing means has a topographical shape corresponding to an elevation value of either end point of the line element. The map element drawing processing means is instructed to overwrite the line element portion with a drawing color or a dotted line different from other portions when the height is smaller than the altitude value. Navigation system. 30. Topographical data storage means for storing topographical shape data capable of giving elevation values to topographical plane coordinates, and position information and incidental information for displaying line figures such as roads, rivers and railways on a map. A line graphic data storage means for storing information, a position name for displaying a place name, a character string such as an icon, etc. and a pattern on a map and a place name for storing incidental information, a background data storage means, and a displayed map position. Display reference point position coordinates and line-of-sight direction angle input means for determining the direction, and display reference point position coordinates and line-of-sight direction angle input from the display reference point input means Display target area determining means for determining a target area (display target area) on the map displayed on the map, and a sample having a predetermined density in the display target area determined by the display target area determining means. And a vertical point z corresponding to the plane coordinates (x, y) of each sampling point is read from the topographical data storage means to generate a three-dimensional sampling point (x, y, z) group. A topographical shape modeling means for creating a polyhedral shaped topographical shape model by connecting the three-dimensional sampling point groups with ridge lines according to a predetermined rule; and display reference points input from the display reference point input means. Display reference point elevation determining means for determining the elevation value of the display reference point from the position coordinates and the topographic shape model obtained by the topographic shape modeling means, and the display reference point position input from the display reference point input means. Viewpoint coordinates for determining perspective coordinates for perspective projection conversion from the coordinates and the line-of-sight direction angle, and the display reference point elevation value determined by the display reference point elevation determination means. Determining means and line figure data corresponding to the display target area from the line figure data storage means, the place name, the place name and background data from the background data storage means, and if necessary, by the topographical shape modeling means Map element elevation determining means for determining the elevation value of each line figure, place name, display point such as icon based on the obtained topographical shape model, and creating display figure data, and the viewpoint determined by the viewpoint coordinate determining means. Perspective projection conversion of the terrain shape model and the line graphic for which the elevation value has been determined and display graphic data such as a place name and an icon based on the coordinates and the line-of-sight direction angle input from the display reference point and other input means. Coordinate transformation means, and drawing the data perspective-transformed by the coordinate transformation means while performing hidden surface removal, and outputting a stereoscopic map image. Image processing means, line figure data elevation comparing means for comparing the elevation value of the end point of each line element of the line figure data determined by the map element elevation determining means and the elevation value of the corresponding terrain shape, and the line figure data Based on the comparison result of the altitude comparing means, line figure data drawn by overwriting the topographical shape for which the elevation value of the end point of the line element of the line figure is equal to or higher than the corresponding topographical shape. A navigation system comprising: drawing processing means; and an image display means for displaying the stereoscopic map image from the drawing processing means and the line graphic image from the line graphic data drawing processing means by combining them. 31. The line graphic data drawing processing means, when the line graphic is a guide route, draws with a drawing color different from that of the case where the line graphic is an ordinary road, or a different line type. 31. The navigation system according to claim 30, characterized in that 32. The line graphic data altitude comparing means is adapted to the line graphic data drawing processing means when the altitude values of both end points of each line element of the line graphic are equal to or larger than the altitude value of the corresponding topographical shape. The navigation system according to claim 30 or 31, wherein an overwrite command for the line element is output. 33. The line graphic data altitude comparing means is adapted to the line graphic data drawing processing means when the altitude value of either end point of each line element of the line graphic is smaller than the altitude value of the corresponding terrain shape. The navigation system according to claim 30 or 31, wherein an instruction is given to overwrite the line element portion with a drawing color or a dotted line different from other portions. 34. determining the display target area based on the position coordinates and the line-of-sight direction angle data of the display reference point, line cormorants step modeling the terrain shape capture terrain shape data corresponding to the display target area And a step of determining the elevation value of the display reference point from the position coordinates of the display reference point and the terrain shape model, from the position coordinates and the line-of-sight angle of the display reference point, from the display reference point elevation value determining the viewpoint coordinates of the perspective projection transformation
A step, a step of the display takes in the map display element data corresponding to the target region, to create a display graphic data to determine the elevation of each map display element based on the terrain shape model if necessary, the A step of performing perspective projection conversion of the terrain shape model and the map display element for which the elevation value is determined based on the viewpoint coordinates and the line-of-sight direction angle; and a three-dimensional map image signal is generated from the perspective projection converted data. A navigator that causes a computer to perform steps and
A medium storing a navigation program, characterized by storing a navigation program. 35. A step of determining a display target area based on position coordinates of display reference points and line-of-sight direction angle data, and a sampling point group having a predetermined density is set in the display target area, and plane coordinates of each sampling point are set. By taking the corresponding elevation value z with respect to (x, y) to generate a group of three-dimensional sampling points (x, y, z) and connecting the three-dimensional sampling points with an edge line according to a predetermined rule. Creates an open polyhedral terrain model.
-Up and, determining the elevation of the display reference point and a position coordinate of the display reference point and the terrain shape model, the position coordinates and viewing direction angle of the display reference point, elevation of the display reference point to determine the viewpoint coordinates of the perspective projection transformation from the value
And step of importing map display element data corresponding to the display target area, and determining the elevation value of each map display element based on the terrain shape model as necessary to create display graphic data.
The step of performing the perspective projection conversion of the terrain shape model and the map display element for which the elevation value is determined based on the viewpoint coordinates and the line-of-sight direction angle, and showing the terrain shape subjected to the perspective projection conversion. A step of generating an image signal for drawing the polyhedron by overwriting from the surface on the back side with respect to the viewpoint, and comparing the altitude value of the display position of each of the map display elements with the corresponding altitude value of the terrain shape model. and generating an image signal to be drawn by overwriting on the basis of this comparison result, for those the greater altitude value than the terrain shape corresponding the direction of the map display element to the terrain shape model
Program that causes a computer to run
A medium storing a navigation program characterized by storing the following. 36. A step of determining a display target area based on position coordinates of display reference points and line-of-sight direction angle data, and a sampling point group having a predetermined density is set in the display target area, and plane coordinates of each sampling point are set. By taking the corresponding elevation value z with respect to (x, y) to generate a group of three-dimensional sampling points (x, y, z) and connecting the three-dimensional sampling points with an edge line according to a predetermined rule. Creates an open polyhedral terrain model.
-Up and, determining the elevation of the display reference point and a position coordinate of the display reference point and the terrain shape model, the position coordinates and viewing direction angle of the display reference point, elevation of the display reference point to determine the viewpoint coordinates of the perspective projection transformation from the value
And a line figure data corresponding to the display target area,
In addition, place name and background data are taken in, and if necessary, the elevation values of the display points of each line figure and place name, icon, etc. are determined based on the terrain shape model to create display figure data .
The step of performing perspective projection conversion of the terrain shape model and the line figure for which the elevation value has been determined and the display figure data such as a place name and an icon based on the viewpoint coordinates and the line-of-sight direction angle.
And a step of drawing the perspective-transformed data while performing hidden surface removal to generate a stereoscopic map image signal, and together with this, a terrain shape model corresponding to the elevation value of the end point of each line element of the line figure. The image signal to be overwritten on the topographical shape model when the elevation value of the end point of the line element of the line figure is larger than the corresponding elevation value of the topographical shape model based on the comparison result. to generate a step
Navigation program that causes the computer to execute
A medium storing a navigation program characterized by storing a RAM.