JP2003029626A - Birds-eye view creating method, map display device and navigation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a navigation system enabling a map to be displayed as a birds-eye view. SOLUTION: The input of the position of a viewpoint is received to determine, based on the coordinate of the present position and the destination and the viewpoint position, a projection plane so that the two points after perspective transformation is plotted on the predetermined position. Or, the input of reduction ratio is received to determine, based on the coordinate of the two points and the reduction ratio, the viewpoint position and the projection plane so that the two points after perspective transformation are plotted on the predetermined position and the reduction ratio of plotting coincides with the inputted reduction ratio. Or, the input of projection angle is received to determine the projection plane based on the projection angle and the viewpoint position. The birds-eye view is obtained by carrying out perspective transformation of map data on the projection plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation system for measuring the position of a moving body and notifying a user of the current position, and a map display device used in the system.

[0002]

2. Description of the Related Art In a navigation system mounted on a moving body, information from various sensors is arithmetically processed to measure the position of the moving body and display the position.

This navigation system uses a position measuring device for measuring the absolute position of a moving body and a two-dimensional vector obtained by projecting points on the ground such as roads and structures onto a plane obtained by mesh division by universal transverse Mercator projection. Required from a storage device that stores map data consisting of data and character data accompanying them, an input device that receives instructions from the outside, and a map mesh stored in the storage device according to instructions input from the input device And a display device that displays a map on the display by reading the vector data and converting the vector data.

Here, the data conversion processing includes movement conversion for changing the display position of the map, scale conversion such as enlargement / reduction used for displaying the map at an arbitrary scale, and rotation for changing the display direction of the map. There is conversion. By these processes, a plane map in which the ground is drawn by an orthogonal projection from directly above is displayed on the display.

[0005]

In the conventional navigation system, when the map is displayed, the ground map is displayed by orthographic projection from directly above. for that reason,
There is a problem that if two points that are distant from each other are displayed at the same time, the scale is inevitably increased and detailed information cannot be displayed.

Therefore, according to the present invention, when a plane (ground) is viewed obliquely from a viewpoint of an arbitrary height, a projection diagram projected on an arbitrary plane between the plane (ground) and the viewpoint is used. An object of the present invention is to provide a bird's-eye view creating method for expressing a map using a certain bird's-eye view, a map display device, and a navigation system including the device.

[0007]

In order to achieve the above object, the present invention is a bird's-eye view creating method for creating drawing data of a map represented by a bird's-eye view by using map data. A bird's-eye view creating method is provided, which is characterized in that the coordinate data included in the map data is perspective-transformed to create a bird's-eye view drawing data on a defined projection plane as a viewpoint.

In the bird's-eye view creating method of the present invention, the step of accepting the input of the position of the viewpoint, the coordinates of two predetermined points (for example, the current position and the destination) included in the map data, and the above-mentioned It is preferable that the projection plane is determined based on the input viewpoint position so that the drawing positions of the two points after the perspective conversion become predetermined positions.

Alternatively, the step of accepting an input of a scale factor, the coordinates of two predetermined points included in the map data, and the two points after the perspective transformation based on the input scale factor. The step of deciding the position of the viewpoint and the projection plane may be provided so that the drawing position becomes a predetermined position and the drawing scale becomes the input scale.

Further, a step of receiving an input of a projection angle which is an angle formed by the plane defined by the map data and the projection plane, based on the input projection angle and the determined viewpoint position, And the step of determining the projection plane.

Further, the present invention provides a map display device for displaying a bird's-eye view by using the above-mentioned bird's-eye view drawing method, and a navigation system for displaying a map by the map display device.

[0012]

In the bird's-eye view display device and the navigation system of the present invention, the map drawing means includes the coordinate conversion means, and the coordinate conversion means performs perspective conversion to convert and display the map in the bird's-eye view. Therefore, according to the present invention, the user can obtain a bird's-eye view map display that is easy to see and in which the positional relationship of points displayed in the map is easy to recognize. According to the bird's-eye view creation method of the present invention, the viewpoint position can be arbitrarily set, so that the needs of the user can be appropriately met.

It should be noted that a navigation system with better operability and convenience can be obtained by adopting a configuration that solves the following first to seventh problems.

First, when the processing speed of the scroll processing in the bird's-eye view display is slower than that in the plane display, the operability is poor when the scroll processing is frequently used to search a predetermined point in the bird's-eye view display. It may become.

Therefore, in the present invention, it is desirable that the two-dimensional map display and the bird's-eye view display can be arbitrarily switched. By doing this, it is possible to display both the plan view and the bird's-eye view according to the user's request,
The convenience is improved.

In such a case, there is a second problem that it becomes difficult for the user to grasp the positional relationship when switching between the planar map display and the bird's-eye view display. This is because the point of view of the map changes,
This is because the position at which a certain point is displayed on the screen changes significantly, and a point that has not been displayed until now is displayed or not displayed.

Therefore, in the present invention, when it is possible to switch between the plan view display and the bird's-eye view display, at the time of switching between the bird's-eye view display and the plan map display, the angle between the plane projecting the map and the plane containing the map data is set. It is desirable to gradually increase or decrease over time. That is,
In the present invention, it is desirable that the viewpoint for obtaining the bird's-eye view moves smoothly in the conversion between the planar map display and the bird's-eye view display. In this way, since the transition between the plan view and the bird's-eye view is smoothly performed, it is possible to easily recognize the correlation between the point displayed on the plan map and the point displayed on the bird's-eye map.

Thirdly, when a map is displayed in a bird's-eye view, if the viewpoint information, which is a parameter of perspective transformation, is fixed at a certain position, the position of the current position displayed on the screen is moved along with the movement of the current position. Then, there is a problem that the mark of the current position is not displayed when the map area deviates from the displayed map area.

Therefore, in the present invention, the viewpoint for obtaining the bird's-eye view can be always fixed at a position away from the current position in a certain direction and a certain distance. Also, the height of the viewpoint can be changed according to the operation input. If the viewpoint is fixed, the bird's-eye view is displayed so that the current position is always fixed at a certain point on the screen, so that the user can easily grasp the current position. Further, if the viewpoint position can be set to a position desired by the user, convenience is improved.

Further, when it is attempted to display two certain points on the same screen, the scale may be updated according to the distance between the two points in the conventional planar map display, but only the scale is updated in the bird's eye view display of the map. Then, there is a fourth problem that the map cannot be displayed optimally.

Therefore, in the present invention, a plane on which the designation of the positions of two points (for example, the current position and the destination) is accepted and the viewpoint and the map are projected so that the two positions are displayed at the predetermined positions on the screen. The angle formed by the plane containing the map data may be determined, and the bird's-eye view display may be executed using the result. By doing so, the positional relationship between the two points can be easily determined. Further, even if the positions of the two points are changed, they are always displayed on the same screen, so that the user can grasp the positional relationship between the two points without performing a complicated operation.

Further, in the present invention, the line background of roads and railroads, the surface background of rivers and green areas, and character strings are perspective-transformed and drawn when displaying a bird's-eye view. However, when the character string is perspective-transformed, there is a fifth problem that the shape of the character far from the viewpoint is small and distorted, and the character near the viewpoint is enlarged to make the character string difficult to read.

Therefore, it is desirable that the coordinate conversion means of the present invention does not perform perspective conversion for character images. By doing so, the characters included in the bird's-eye view are displayed upright in the same size, which makes it easier to read the character string.

Further, when displaying a lot of character data, the character strings are displayed overlapping each other. Particularly, in the bird's-eye view, since the depression angle from the viewpoint is small in the distance from the viewpoint, the reduction rate is large and the character data displayed per unit area is large. Therefore, in the bird's-eye view, there is a sixth problem that character data and character data are likely to overlap each other at a distance from the viewpoint.

Therefore, the drawing determination means of the present invention, the closer the character data position in the map data is from the viewpoint,
It is desirable to give higher priority to the display of the character data. In this way, by displaying the one with the higher priority over the one with the lower priority, it is possible to prevent the character string from being lost and make the reading easier.

When the current position is near the bottom or near the viewpoint, it is preferable that the displayed height or the distance from the viewpoint is used as a reference for this priority. When there are two or more character strings that are displayed in an overlapping manner, the lower the displayed height (height from the bottom of the display screen) (or the closer the distance from the viewpoint), the higher the priority (that is, other characters). If it is displayed so as not to be covered by a column and overlaid on another character string), the character data in the vicinity of the current position is displayed without being lost by being covered by another display. Therefore, in this way, it is possible to prevent the loss of character information near the current location that the user may desire, and it becomes easy to read the character string.

As described above, when the bird's-eye view display is performed, a large amount of line data, surface background data, and character data are drawn per unit area in a region far from the viewpoint (a region with a small depression angle). Therefore, when drawing character data of these data over other data,
In the area far from the viewpoint, since the line data and the surface background data are covered by the character data, there is a seventh problem that it is difficult to read the shape of the road or the like far from the viewpoint.

Therefore, if the drawing height of the character string on the screen obtained as a result of the perspective transformation of the map is higher than a predetermined value, the drawing judging means of the present invention preferably deletes it from the drawing object. . Alternatively, the drawing determination means, for a character string defined at a position more than a predetermined distance from the viewpoint,
It may be deleted from the drawing target. in this way,
Do not draw a character string in an area that is more than a certain height or more than a certain distance, that is, in the bird's-eye view display, the depression angle is small and the amount of data drawn per unit area is very large. By doing
The road display and the surface background display in this area are not covered by the character string display. Therefore, in this way, there is an advantage that the recognition of roads and the like far from the viewpoint is not disturbed even if the bird's-eye view display is performed.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a bird's-eye view map displayed by the bird's-eye view map display device installed in the navigation system of this embodiment. The bird's-eye view display device of this embodiment creates a bird's-eye view 102 showing a bird's-eye view from a specific position as a projection view of two-dimensional map data (shown as 101 in FIG. 1) and displays it on the display screen of the display 2. In addition,
In the bird's-eye view 102 shown in FIG. 1, the route 104 is highlighted to show the route (in FIG. 1, the line is thickened to make the line thicker, but it is highlighted by blinking or discoloring. Good). The mark 105 is a symbol for indicating the current position. Further, in FIG. 1, the arrow indicates 2
The projection relationship from the three-dimensional map data 101 to the bird's-eye view 102 is shown.

FIG. 17 is an external perspective view of the mobile body navigation system of this embodiment. The navigation system of the present embodiment is housed in a housing 69, and the housing 69 has a display screen of the display 2 and a scroll key 66.
A scale change key 67, a projection angle change key 68, and a touch panel 70 provided on the display screen of the display 2.
And so on.

The scroll key 66 is a key for accepting a scroll instruction of an image displayed on the display screen, and includes four direction designation keys 660 for accepting a scroll instruction of up, down, left and right. The scale change key 67 is a key for accepting a change in the scale of the map displayed on the display screen, and includes two scale specifying keys 67a, 67b for accepting enlargement and reduction, respectively. The projection angle change key 68 is a key for accepting the designation of the angle of the projection surface of the bird's-eye view displayed on the display screen, and is provided with two angle designation keys 68a, 68b for accepting the rise and fall of the projection angle, respectively. . The touch panel 70 is an input unit that detects a touch on the surface of the touch panel 70 and outputs the touched position.

As shown in FIG. 2, the mobile navigation system according to the present embodiment includes an arithmetic processing unit 1 and a display 2 connected to the arithmetic processing unit 1 via a signal line S1.
A map storage device 3 connected to the arithmetic processing unit 1 via a signal line S2, a voice input / output device 4 connected to the arithmetic processing unit 1 via a signal line S3, and a signal to the arithmetic processing unit 1 Line S
4, an input device 5 connected to the arithmetic processing unit 1, a wheel speed sensor 6 connected to the arithmetic processing unit 1 via a signal line S5, and a geomagnetic sensor connected to the arithmetic processing unit 1 via a signal line S6. 7, a gyro 8 connected to the arithmetic processing unit 1 via a signal line S7, a GPS (Global Positioning System) receiving device 9 connected to the arithmetic processing unit 1 via a signal line S8, and the arithmetic processing The traffic information receiving device 10 is connected to the section 1 via a signal line S9. In addition, each signal line S
1 to S9 may be wired or wireless as long as they can transmit a signal, but a wired line is used in this embodiment.

The arithmetic processing unit 1 detects the current position based on the information output from the various sensors 6 to 9, and reads necessary map information from the map storage device 3 based on the obtained current position information. , Develop map data in graphics, display the current location mark on the display, select the most suitable road connecting the destination and the current location instructed by the user, and inform the user using voice or graphic display, etc. It is a central unit that performs various processes such as.

The display 2 is a unit for displaying the graphics information generated by the arithmetic processing unit 1, and is a CRT.
And a liquid crystal display. In addition, S1 between the normal arithmetic processing unit and the display is the RGB (Red Green Blue) signal or N in this embodiment as well as the normal system.
Connect with a TSC (National Television System Committee) signal.

The map storage device 3 is a CD-ROM (Compac
t Disk-Read Only Memory) and IC (Integrated Circ)
uit) A large-capacity storage medium such as a card, and a reading process for reading data held in the large-capacity storage medium and notifying the data to the arithmetic processing unit 1 in response to a request from the arithmetic processing unit 1. A writing process is performed to store the data notified by No. 1 in the mass storage medium.

Further, the voice input / output device 4 includes an arithmetic processing unit 1
The message generated to the user is converted, the voice is output, the voice input is accepted, the content is recognized, and the process is transferred to the arithmetic processing unit 1.

The input device 5 is a unit that receives an instruction input from the outside, and in the present embodiment, the scroll key 66, the scale change key 67, and the projection angle change key 6 described above.
8 and a touch panel 70. The configuration of the input device 5 is not limited to this, and other input means such as a joystick, a keyboard, a mouse, and a pen input device may be used.

As a sensor used to detect a position in mobile navigation, the navigation system of this embodiment measures the distance from the product of the wheel circumference and the measured wheel rotation speed, and further The wheel speed sensor 6 that measures the angle at which the moving body bends from the difference in the number of rotations of the wheels, the geomagnetic sensor 7 that detects the magnetic field held by the earth and the direction in which the moving body is facing, and the moving body A gyro 8 composed of an optical fiber gyro, a vibration gyro, etc., which measures the angle of rotation, and a signal from a GPS satellite is received, and the distance between the mobile body and the GPS satellite and the rate of change of distance are 3 or more GPS receiver 9 for measuring the current position, traveling direction and traveling direction of the moving body by measuring with respect to
Equipped with.

Further, the navigation system of the present embodiment is equipped with a traffic information receiving device 10 for receiving signals from beacon transmitters and FM broadcasts that issue traffic information such as road congestion, construction, road closure information and parking lot information. .

The hardware configuration of the arithmetic processing unit 1 described above is shown in FIG. The arithmetic processing unit 1 is a CPU that executes processing such as numerical calculation and control of each device 22 to 31.
(Central Processing Unit) 21 and RAM (Random Access Memory) 2 for holding maps and calculation data
2 and ROM (Read OnlyM) for holding programs
emory) 23 and high-speed memory-between memory and memory-
DMA (Direct M) that executes data transfer between each device
emory Access) 24, a drawing controller 25 that executes graphics drawing at high speed such as expanding vector data into an image, and performs display control, and a VRAM (Video Random A) that stores graphics image data.
ccess Memory) 26, a color palette 27 that converts image data into RGB signals, and an A / D (Analog / Digital) converter 28 that converts analog signals into digital signals.
And an SCI (Serial Communication Interface) 29 for converting a serial signal into a parallel signal synchronized with the bus.
And I / O that is placed on the bus in synchronization with the parallel signal
An (Input / Output) device 30 and a counter 31 for integrating a pulse signal are provided. These devices 21-31
Are connected to each other by a bus.

Next, the functional configuration of the processing operation unit 1 will be described with reference to FIG. The processing calculation unit 1 includes a user operation analysis unit 41, a route calculation unit 42, and a route guidance unit 43.
, Map drawing means 44, current position calculation means 45, map matching processing means 46, and data reading processing means 4
7, a menu drawing means 48, and a graphics processing means 49. Each of these means 41 to 49 is an RO
It is realized by the CPU 21 executing the instruction held in M23.

The current position calculating means 45 is composed of the wheel speed sensor 6
By using the distance data and the angle data obtained as a result of integrating the distance pulse data measured by the gyro 8 and the angular acceleration data measured by the gyro 8, by integrating the data on the time axis, the initial position (X , Y), the processing for calculating the position (X ′, Y ′) after traveling of the mobile body is performed. Here, the current position calculation means 45 corrects the absolute azimuth of the direction of travel from the azimuth data obtained from the geomagnetic sensor 7 and the angle data obtained from the gyro in order to match the relationship between the rotated angle of the moving body and the direction of travel. . When the data obtained from the sensor is integrated as described above, the error of the sensor accumulates. Therefore, the current position calculation means 45
Based on the position data obtained from the GPS receiving device 9, a correction process of canceling the accumulated error is performed at a predetermined time period (every 1 second in this embodiment), and this current position information is obtained. Output the corrected data.

The current position information thus obtained still contains a minute error due to the sensor. Therefore, in order to further improve the position accuracy, in the navigation system of the present embodiment, the map matching processing means 46 performs the map matching processing. This is the road data included in the map around the current location read by the data reading processing means 47 and the current position calculating means 4
This is a process of comparing the traveling loci obtained from No. 5 with each other and fitting the current position to the road having the highest shape correlation. By performing the map matching process, the current location will often coincide with the road on which the vehicle is traveling, so that the current location information can be accurately output.

On the other hand, the user operation analysis means 41 analyzes the request contents of the operation instruction received via the input device 5, and the respective units 42 to 4 are executed so that the corresponding processing is executed.
Control eight. For example, when a route guidance request to a destination is input, the map drawing means 44 is requested to display a map for setting the destination, and then a process for calculating a route from the current location to the destination is performed. It operates so as to request the calculation means 42 and the route guidance means 43 to perform processing for presenting route guidance information to the user.

The route calculation means 42 searches for a node connecting two designated points using the Dijkstra method or the like, and obtains the route having the highest priority. The path calculation unit 42 has a plurality of priority order criteria, and uses the criteria specified by the operation instruction to determine the path. In the present embodiment, a route that minimizes the distance between two points, a route that can be reached in the shortest time, a route that costs the least, and the like are required according to the operation instruction.

The route guide means 43 is provided with the link information of the guide route obtained by the route calculation means 42 and the current position calculation means 4.
5 and the current position information obtained by the map match processing means 46 are compared, and whether or not to go straight before passing an intersection or the like,
Voice input / output device 4 provides direction information such as whether to turn left or right.
To output as voice, or draw a direction to proceed on the map displayed on the display screen of the display 2.

The data reading processing means 47 operates so as to prepare for reading the map data of the requested area from the map storage device 3. The map drawing means 44 receives the map data around the point designated for display from the data reading processing means 47 and draws the designated object at the designated scale and in the designated direction in the upward direction. To the graphic processing means 49.

On the other hand, the menu drawing means 48 operates so as to receive the command output from the user operation analyzing means 41 and transfer the commands for drawing various kinds of required menus to the graphic processing means 49.

The graphics processing means 49 receives the drawing commands generated by the map drawing means 44 and the menu drawing means 48 and develops an image in the VRAM 26.

Next, the function of the map drawing means 44 will be described with reference to FIG. The map drawing means 44 includes an initial data clipping means 61, a coordinate converting means 62, and a drawing determining means 6
3, data clip means 64, and drawing command issuing means 6
5 and 5.

The initial data clipping means 61 uses the respective meshes of the map data fetched from the map storage device 3 by the data reading processing means 47 to extract road data, plane and line background data, and character data relating to areas required for subsequent processing. Is selected by the clip processing, and the result is notified to the coordinate conversion means 62. In the present embodiment, the initial data clip means 61 is activated every 0.5 seconds. It is also activated by an operation instruction notification from the user operation analysis means 41.

As a clip processing algorithm used here, for road data and line data, Cohen-
The Sutherland line clipping algorithm and the Surface-Hodgman polygon clipping algorithm for surface data are available (Foley, van Da
m, Feiner, Hughes: Computer Graphics: Addison-We
sley Publishing Company pp.111-127). By this processing, it is possible to reduce the amount of data that should be subjected to the subsequent coordinate conversion and drawing processing, and therefore it is expected to speed up.

The coordinate conversion means 62 is used for enlarging / reducing, rotating, projecting, etc. the map data obtained by the clipping process.
The process of converting each coordinate value of the map data is performed. The coordinate conversion means 62 is activated in response to the notification from the initial data clipping means 61 or the user operation analysis means 41.

The drawing determination means 63 functions to select the data that needs to be actually drawn from the map data obtained by the coordinate conversion means 62. For example, the drawing determination means 63
When the scale becomes large, the amount of data to be drawn is substantially increased, so that the operation is performed so as to delete a narrow road or an optional place name. This makes it possible to prevent the processing speed for drawing from becoming extremely slow. The drawing determination means 63 is the coordinate conversion means 62 or the user operation analysis means 4.
It is activated in response to the notification from 1.

The data clipping means 64 operates so as to select map data relating to the drawing area from the map data obtained by the drawing judging means 63 by clipping processing. As the clip processing algorithm used here, the same algorithm as the initial data clipping means can be used. The data clip means 64 is activated in response to the notification from the drawing determination means 63 or the user operation analysis means 41. The data clip means 64 may be omitted.

The drawing command issuing means 65 draws roads, planes and lines, background data, character data, etc. included in the map data obtained by the data clipping means 64 in a specified color or pattern, so that lines and polygons are drawn. , A command for drawing a character or the like and a command for setting a color or a pattern are issued to the graphics processing means 49. The drawing command issuing means 65 is activated in response to the notification from the data clip means 64.

In this embodiment, the initial data clipping means 6
1 is activated every 0.5 seconds and notifies the coordinate conversion means 62 of the data obtained as a result of the clip processing. Therefore,
In this embodiment, except for the case of an operation instruction from the outside,
Drawing will be performed every 0.5 seconds.

Next, the outline of the bird's-eye view display will be described with reference to FIG. In the printed atlas and the conventional navigation system, when the map is displayed, it is represented by a plane map display in which the map is viewed from the point at infinity from the ground. The planar map display has an advantage that the scale is constant within the same screen regardless of the location, and thus it is easy to grasp the sense of distance. But,
When trying to display a certain two points on the same screen, it is necessary to perform an operation to adjust the scale of displaying the map to the optimum, and it is possible to display them at a time if the distance between the two points is large. Since the amount of information is limited by the size and definition of the display, there is a drawback that only limited information can be displayed. There is a bird's-eye view display as a means for solving this problem.

The bird's-eye view display is two-dimensional or three-dimensional on the plane A.
This is realized by perspective transformation in which the dimensional map information 63 is projected onto a plane B forming an angle θ with the plane A to obtain projection drawing information 64. In the conceptual diagram shown in FIG. 6, coordinates (T
A map 53 (point a, point b, point c, point d) is represented by a rectangle with a point 55 of (x, Ty, Tz) as a viewpoint and is represented by a rectangle on a plane A (illustrated as a rectangle 51). Is projected onto a plane B (illustrated as a quadrangle 52) forming an angle θ with the plane A, and is represented by a quadrangle having projections 54 (points a ′, b ′, c ′, and d ′ as vertices). Is shown). Here, point a, point b, point c, and point d on the map 53 are point a ′, point b ′, point c ′, and point a, respectively.
It is projected at point d '. In the present specification,
In the projection process, the viewpoint 55, which is the origin of the viewpoint coordinate system,
We simply call it "viewpoint". In the present specification, simply referring to “viewpoint” does not mean “viewpoint” as the position of the user's eyes.

When the bird's-eye view representation is performed, information of a portion near the viewpoint 55 (for example, straight line ab) is enlarged, and information of a portion far from the viewpoint (for example, straight line cd) is reduced and expressed.
As a result, when displaying two points on the same screen, the point for which more detailed information is to be obtained is near the viewpoint, the other is far from the viewpoint, and the two points are displayed on the same screen. It becomes possible to express the mutual positional distances in an easy-to-understand manner and to provide the user with a larger amount of information near the viewpoint.

In this embodiment, since it is possible to use two-dimensional map data as the map information used for the bird's-eye view display, by adding a means for performing such perspective transformation to the conventional navigation system, A bird's-eye view display can be realized without adding a large amount of map data. In the present embodiment, the perspective transformation is executed by the coordinate transformation means 62. In order to realize the bird's-eye view display, it is desirable to make various efforts as described later.

First, a method of realizing a basic bird's-eye view display will be described with reference to FIG. First, the coordinate conversion means 62
Determines the position of the viewpoint, determines which direction to view from the viewpoint position, and the angle of the projection plane (illustrated as angle θ in FIG. 6) (step 1). As a result, the area to be displayed in the bird's-eye view is determined. When a bird's-eye view is displayed on a rectangular display screen, the area near the viewpoint is narrow and the area far from the viewpoint is wide. Therefore, the finally drawn map data becomes the trapezoidal area 72 in the map mesh 71.

Next, the coordinate conversion means 62 uses the initial data clipping means 61 to draw the trapezoidal area 7 actually drawn from the map mesh data 71 including the area to be displayed in the bird's-eye view.
The map data of the rectangular area 73 circumscribing 2 is extracted (step 2).

Next, the coordinate conversion means 62 enlarges or reduces the extracted data and then performs an affine transformation to make the trapezoid erect, and then further performs perspective transformation to convert each coordinate value of the map data into the data. Convert (step 3).
At this time, the coordinate transformation by the affine transformation is performed on the plane A.
Is the angle between the plane B and the plane B, the map data coordinate value before conversion is (x, y), and the map data coordinate value after conversion is (x ',
y ′), it is expressed by the following (Equation 1).

[0065]

[Equation 1]

In the coordinate conversion in the perspective processing at this time, the position coordinates of the viewpoint are (Tx, Ty, Tz), and the plane A is used.
Is the angle between the plane B and the plane B, the map data coordinate value before conversion is (x, y), and the map data coordinate value after conversion is (x ',
y ′) is expressed by the following (Equation 2) and (Equation 3).

[0067]

[Equation 2]

[0068]

[Equation 3]

In step 3, the drawing target area which was the trapezoid 72 at the time of step 2 is converted into the rectangular area 74, and the rectangle 73 circumscribing the trapezoid 72 is coordinate-converted into the rectangle 75 circumscribing the rectangle. Here, it is not necessary to draw the portion outside the drawing target area 74 in the area within the rectangle 75. Therefore, the coordinate conversion means 62 uses the data clipping means 64 to clip and remove the area outside the rectangular area 74 to be drawn (step 4).

The map data thus obtained is notified to the drawing command issuing means 65. Drawing command issuing means 6
5 uses the notified map data to generate a drawing command and causes the graphics processing means 49 to create drawing data. The graphics processing means 49 creates drawing data, stores it in the VRAM 26, and instructs the display 2 to display. The display 2 displays the drawing data held in the VRAM 26 on the display screen. As a result, the bird's-eye view map 102 as shown in FIG. 1 is displayed on the display screen of the display 2.

By using the bird's-eye view display, it is easy to recognize the azimuth and distance relationship between any two points. Furthermore, the bird's-eye view display is suitable for providing detailed information around a certain point and providing general information around another point. In this way, when providing detailed information or outline information around a specific point, the coordinates of the specific point may be set in advance, or the position can be determined by obtaining the coordinates that satisfy the predetermined conditions. May be defined, and the input of the position of the point may be accepted.

In the navigation system, the current location is often selected as one of the points. The position information of the present position is obtained from the present position calculating means 45 or the map matching processing means 46. Therefore, when the current position is designated to either the detailed information display point or the general information display point via the input device 5, the map drawing means 44 obtains from the current position calculation means 45 or the map match processing means 46. Use the coordinates of the current location.

However, in the case where the designation of the position on the map displayed on the display screen is accepted as either the detailed information display point or the general information display point, the user selects the point for displaying the detailed information or the general information. You often have to scroll through the map to find it. However, in the bird's-eye view display, the scroll speed is slow because it is necessary to redraw the entire surface every time the display area is changed. Therefore, there is a problem in that the operation of varying the scroll display is inconvenient.

In order to solve this problem, in this embodiment,
In the coordinate conversion, the processing shown in FIG. 8 is performed.

First, if it is necessary to enlarge or reduce the map (step 1000), the coordinate conversion means 62 performs enlargement or reduction calculation on the region to be processed (step 1010), and it is necessary to rotate the map. Ba (Step 1
020) and rotation conversion processing (step 1030). The rotation conversion process (step 1030) includes a rotation angle calculation (step 1031) and an affine conversion calculation (step 1032).

Next, the coordinate conversion means 62 determines whether or not the bird's-eye view display is performed (step 1040). here,
For example, when an instruction to search for an arbitrary point on the map is input via the input device 5 or when an instruction to display a plan view is input via the input device 5, the coordinate conversion means 62 is a bird's-eye view display determination (step 1040)
In, it is determined that the perspective transformation is not performed, and the perspective transformation processing (step 1050) is not executed, and the coordinate transformation processing ends. In this case, since the perspective conversion process is not executed,
A plane map is displayed on the display screen of the display 2.

According to the present embodiment, in the operation of searching for an arbitrary point in the map, the map is displayed not as a bird's-eye view but as a planar map, so that the target point can be quickly searched for.

Further, for example, when a bird's-eye view display instruction is input through the input device 5 or when an arbitrary point is designated as a destination through the input device 5 during the plan view display, etc. Then, the coordinate conversion means 62 that has received those instructions via the user operation analysis means 41 performs step 104.
In the bird's-eye view display determination at 0, it is determined that perspective conversion is required, and perspective conversion processing (step 1050) is executed.

This perspective conversion process (step 1050) includes a projection angle calculation (step 1051), a projection surface position calculation (step 1052), and a perspective conversion calculation (step 1053). As a result, the map data notified to the drawing command issuing means 65 is converted into the bird's-eye view, and therefore the graphics processing means 49.
The drawing data created by and stored in the VRAM 26 is also a bird's-eye view. Therefore, the map displayed on the display 2 is also switched from the plan view to the bird's-eye view.

As described above, the bird's-eye view can be arbitrarily switched to the plan view and the plan view can be arbitrarily switched to the bird's-eye view. Therefore, according to the present embodiment, an easy-to-understand map representation can be provided.

In addition, the screen switching from the plane map to the bird's-eye view occurring in the above processing, or the user switching from the plane map display to the bird's-eye view display or switching from the bird's-eye view to the plane map through the input device 5 or the like. If an instruction is given, if the two-dimensional map and the bird's-eye view are immediately switched, the map representation on the screen changes greatly, and it becomes difficult for the user to recognize the map. Therefore, it is desirable that the transition between the plan view and the bird's-eye view be gradually performed.

In this embodiment, when the screen is switched from the planar map to the bird's-eye view, the projection angle θ is calculated in the perspective conversion process (step 1050) (step 105).
In 1), the projection angle θ is gradually increased (every 0.5 seconds in this embodiment) from 0 ° over time (by 5 ° in this embodiment), and increased when the target projection angle is reached. To make it stop. At this time, the unit of the projection angle to be increased may be a constant value.

As described above, since the projection angle is increased with time and the perspective transformation calculation (step 1053) is performed, the plane map smoothly changes to the bird's-eye view. Therefore, the user can change the position of the point displayed on the plane map and the bird's-eye view. You will be able to easily understand the relationship. Even when the bird's-eye view is switched to the planar map, the same effect as described above can be obtained by gradually decreasing the projection angle that was initially set to 0 degrees in time series.

Next, the angle θ (projection angle) formed by the map and the projection plane, which is the perspective transformation parameter in the bird's-eye view display, and the viewpoint coordinate system including the projection plane viewed from the object coordinate system including the map plane. Origin coordinates (Tx, Ty, Tz),
That is, a method of determining the position of the projection surface will be described with reference to FIGS.

In the navigation system, it is generally desired that the point where the user is currently traveling, that is, the vicinity of the current location is displayed in detail. Therefore, first, as shown in (c) of FIG. 9, a case will be described in which a bird's-eye view display is performed so that the current position is located on the lower side of the center of the screen. In this case, a bird's-eye view is displayed on the screen in front of the traveling direction as viewed from the current location and the road map that has been traveled so far. It should be noted that FIG. 9A shows a field of view (range displayed and displayed) 92 in the map mesh 91, and FIG. 9B shows a viewpoint position and a projection angle for obtaining a bird's-eye view. Also, FIG. 9 (c)
Fig. 2 shows the current position and traveling direction in the obtained bird's-eye view display. In addition, in FIG. 9, a dotted arrow indicates a traveling direction.

In order to realize the bird's-eye view display as shown in FIG. 9C, the coordinate conversion means 62 first executes the necessary enlargement / reduction processing (steps 1000 and 101).
0), determine that rotation is required (step 1020),
As shown in FIG. 9A, an angle φ formed by the traveling direction vector and the bottom of the map mesh is obtained (step 1031), and affine transformation of rotating the map data by the angle φ is performed on each coordinate value. (Step 1
032).

Since it is determined in step 1040 that the bird's-eye view is displayed, the coordinate conversion means 62 executes a process of calculating the projection angle θ and the viewpoint position (step 1051).
And 1052).

If the projection angle θ is set in the vicinity of 0 °, for example, the difference in scale between the vicinity of the viewpoint and the distance from the viewpoint becomes small,
If it is set in the vicinity of 90 °, the difference in scale between the vicinity of the viewpoint and the distance from the viewpoint becomes large. In this embodiment, the projection angle θ is usually set to about 30 ° to 45 °.

In this embodiment, the coordinate conversion means 62
Is an angle change direction instruction (input by the projection angle change key 68) notified from the user operation analysis means 41.
The projection angle θ is changed according to. That is, when the user operation analysis unit 41 detects that the angle instruction key 68a indicating the elevation is pressed, the user operation analysis unit 41 issues an instruction to raise the projection angle to the coordinate conversion unit 6.
Notify 2. Further, each time it detects that the pressing has continued for 0.5 seconds from the notification of the projection angle increasing instruction, the coordinate converting means 62 is notified of the projection angle increasing instruction. The coordinate conversion unit 62 that has received the notification of the rising instruction increases the projection angle θ by 5 ° (that is, increases the projection angle by 5 °). Further, the same is true for the instruction to lower the projection angle, and the depression of the angle instruction key 68b indicating the lowering and 0.
Each time the operation is continued for 5 seconds, the user operation analysis unit 41 notifies the coordinate conversion unit 62 of a projection angle lowering instruction, and the coordinate conversion unit 62 that receives the instruction decreases the projection angle θ by 5 ° (that is, projection). Decrease the angle by 5 °).

By doing so, in this embodiment, the user can arbitrarily set the map area to be displayed in the bird's-eye view map display. In this way, when the increase of the projection angle is instructed, the projection angle θ is increased, so that a farther map is displayed. When the projection angle is decreased, the projection angle θ is decreased when operated, so that the map near the current position is displayed.

Next, the coordinate converting means 62 subtracts the position (Tx, Ty, Tz) of the projection surface from the present position (x, y, z) by subtracting the position (Tx, Ty, Tz) of the projection surface. (Δ
x, Δy, Δz) is always calculated to be a constant value (step 1052). Further, the coordinate conversion means 62 has an absolute value of 0 for Δx, and a small value for Δz when displaying at a small scale corresponding to the scale at which the map is displayed at Δz.
When displaying at a large scale, set a large value for Δz. Normally, Δz should be selected so that the scale of the plan view and the scale of one point near the center of the bird's eye view display match.

It is desirable that the scale of the map can be changed according to the user's request. Therefore, in the present embodiment, the coordinate conversion means 62 changes the scale of the displayed map in accordance with the scale change instruction (input by the scale change key 67) notified from the user operation analysis means 41. That is, the user operation analysis means 41 uses the enlargement instruction key 67a.
When the press of is detected, the enlargement instruction is notified to the coordinate conversion unit 62. Also, the pressing is 0.5 from the notification of this enlargement instruction.
Each time it detects that the second has been continued, the coordinate conversion means 62
Notify to the enlargement instruction. Upon receiving the notification of the enlargement instruction, the coordinate conversion unit 62 increases Δz by a predetermined value in step 1052. The same applies to the reduction instruction. Every time the reduction instruction key 67b is pressed and 0.5 seconds is continued, the user operation analysis unit 41 notifies the coordinate conversion unit 62 of the reduction instruction and receives the coordinate conversion. Means 6
2 reduces Δz by a predetermined value in step 1052.

In the present embodiment, Δy can take a negative value as shown in FIG. 9, but it can also take a positive value as shown in FIG. In this embodiment, the bird's-eye view display can be performed without any problem regardless of whether the viewpoint position is in front of or behind the current position. Note that FIG. 15 is an explanatory diagram for obtaining a bird's-eye view of different viewpoints in the same range as that shown in FIG. 9. FIG. 15A shows a field of view (range displayed and displayed) 152 in the map mesh 151.
5 (b) shows a viewpoint position and a projection angle for obtaining a bird's-eye view. Further, FIG. 15C shows the position and the traveling direction of the current position in the obtained bird's-eye view display. In addition, in FIG. 15, a dotted arrow indicates a traveling direction.

In this embodiment, the coordinate conversion means 62 determines the position of the viewpoint (specifically, Δy) according to the viewpoint position (input by the touch sensor 70) notified from the user operation analysis means 41. decide. That is, when the user operation analysis unit 41 detects a contact with the touch sensor 70, the user operation analysis unit 41 notifies the coordinate conversion unit 62 of the contact position. Upon receiving the notification of the position information, the coordinate conversion means 62 performs step 10
At 52, Δy so that the viewpoint is at the notified position
To set.

As described above, in this embodiment, Δy can be set to an arbitrary value in a wide range from positive to negative in accordance with a user's instruction. Therefore, according to the present embodiment, the position to be displayed in detail can be flexibly set.

Finally, the coordinate conversion means 62 uses the projection angle θ and the position (Tx, T) of the projection surface thus obtained.
y, Tz) is used to perspectively transform each coordinate value of the map data (step 1053). By the graphics processing means 49 performing drawing processing using the obtained map data,
In the bird's-eye view display of the maps shown in FIGS. 9C and 15C, the traveling direction is always upward, and the current position is displayed at the same point on the screen.

In the navigation system, it is desired to display in detail the point where the user is currently traveling, that is, the vicinity of the current location. Therefore, as described above, in the navigation system of the present embodiment, FIG.
As shown in (c), FIG. 15 (c) and FIG. 16 (c), the current location is displayed on the lower side of the center of the screen.

In the navigation system of this embodiment,
The designation of the destination can be accepted through contact with the touch panel 70. When the destination is designated, the navigation system of the present embodiment draws the destination so that it is included in the visual field (range drawn on the display screen).
At this time, the coordinate conversion means 62 causes the current position to be on the lower side of the center of the screen and the destination to be on the upper side of the center of the screen as described above (shown in FIGS. 10C and 16C). ), Determine the rotation angle φ.

A bird's-eye view display method in this case is shown in FIG.
This will be described with reference to FIGS. 10 and 16. 10 is an explanatory diagram for obtaining a bird's-eye view in which both the present location and the destination are drawn on the same screen (field of view), and FIG. 16 is illustrated in FIG.
It is explanatory drawing in the case of obtaining the bird's-eye view of a different viewpoint of the same range as what was shown in FIG. 10 (a) and 16
FIG. 10B and FIG. 16 show a field of view (range displayed and displayed) 162 in the map mesh 161 in FIG.
A viewpoint position and a projection angle for obtaining a bird's-eye view are shown in (b). Further, FIGS. 10C and 16C show the positions of the current position and the destination in the obtained bird's-eye view display.
The dotted arrows in FIGS. 10 and 16 represent the direction of the destination.

[0100] Here, the lower center of the screen is the current position,
The case of displaying the upper center of the screen as the destination will be described as an example. However, when receiving the designation input of any two points and displaying one of the two points on the lower center of the screen and the other on the upper center of the screen, , Are processed in the same manner.

In order to realize the bird's-eye view display as shown in FIGS. 10 (c) and 16 (c), the coordinate conversion means 62, at step 1031, displays the current position as shown in FIGS. 10 (a) and 16 (a). The angle φ formed by the line perpendicular to the line segment connecting the and the destination and the base of the map mesh is obtained, and step 1032 is performed.
At, the coordinate values of the map data to be drawn are affine-transformed by the angle φ.

Since it is determined in step 1040 that the bird's-eye view is to be displayed, the coordinate conversion means 62 moves to the process of calculating the projection angle θ and the viewpoint position (step 10).
51 and 1052). As described above, the initial value of the projection angle θ is a predetermined value of 30 to 40 °,
It is changed according to the input by the projection angle change key 68.
Further, the initial position of the projection surface is also determined so that the difference value obtained by subtracting the position coordinates of the projection surface from the coordinates of the current position from the position coordinates of the projection surface becomes a predetermined value, as described above.
It is changed according to the input by the scale designation key 67. Further, the conversion formulas shown in (Formula 2) and (Formula 3) above are used for the rotation of the coordinates, and the conversion formula shown in (Formula 1) above is used for the affine transformation. As for the parameters Ty and Tz indicating the position of the projection surface, by substituting an appropriate value in Tx, for example, 0, substituting the position coordinates of the current position and the destination and the displayed position, and solving the simultaneous linear equations. Desired.

Next, the coordinate conversion means 62 executes perspective conversion calculation processing (step 1053). That is, the coordinate conversion means 62 perspectively transforms each coordinate value of the map data using the projection angle θ and the position of the projection surface obtained as described above.

As a result, the graphics processing means 49 draws the obtained map data to display the present location and the destination on the same screen. If these processes are executed every time the current location changes, the current location and the destination are displayed at the same position on the same screen even if the current location changes over time. If it is determined that the perspective conversion process is necessary in the determination in step 1040 during the bird's-eye view display, the screen display is always changed in response to the temporal change of the current location.
Further, in the determination in step 1040, only when the current position has moved by a predetermined distance or more,
If it is determined that the perspective conversion process is necessary, only the mark 105 indicating the current position moves on the same bird's-eye view map until the current position moves for a fixed distance, and the current position moves for a fixed distance to approach the destination. Then, the map display will change to an enlarged one.

By executing the above processing each time the current location changes and fixing the positions of the current location and the destination displayed on the screen, the map can be enlarged and displayed as the destination approaches.

When the distance between the present location and the destination is shortened, the projection angle θ is changed to a smaller value so that the relationship between the present location and the destination can be understood by the bird's eye view display when the distance is far. For ease of use, and if the distance between the current location and the destination is close, it is possible to display the display close to the plan view. Alternatively, conversely, as the distance between the current location and the destination becomes shorter, the projection angle θ is changed to a larger value, making it easier to grasp the overall positional relationship when the distance between the current location and the destination is large. Display the plan view so that
The sense of distance may be easily grasped by displaying such that the viewpoint position gradually rises as the distance between the current position and the destination decreases.

Next, a method of drawing character data in the bird's eye view display will be described. First, details of the perspective transformation calculation (step 1053) of the perspective transformation unit 62 will be described with reference to FIG.

The perspective conversion means 62 first determines whether the input map data is surface data (step 1100).
When it is determined that the data is surface data, the perspective conversion unit 62 uses the parameters obtained in the projection angle θ calculation (step 1051) and the viewpoint position calculation (step 1052) to perform the perspective conversion of each node coordinate value of the given surface data. (Step 1101). The perspective transformation process (step 1101) for this node is repeated until the process for all input nodes is completed (step 1102).

Next, the perspective transformation means 62 performs the same processing on the line data as in the plane data, and transforms the coordinate values of each node in perspective (steps 1103 to 1105).

When the processing relating to the line data is completed, the perspective conversion means 62 determines whether the input map data is character data (step 1106). When it is determined that the data is character data, the perspective conversion unit 62 uses the projection angle θ and the viewpoint position coordinate value obtained in steps 1051 and 1052 for the coordinate value of the point where the drawing of the given character string is started. Conversion is performed (step 1107). In addition,
In this embodiment, perspective conversion is not performed on the character image. The node perspective transformation processing in step 1107 is repeated until the processing for all input nodes is completed (step 1108).

When graphics drawing is performed using the obtained perspective conversion result, for example, a bird's-eye view such as the map 103 shown in FIG. 1 is obtained. In this embodiment, step 110
Since the perspective conversion of the character image is not performed in 7,
As shown in the map 103 of FIG. 1, all the characters are drawn in the same size and upright.

Next, the processing of the drawing determination means 63 will be described with reference to FIG. It is means for determining whether or not to draw each data included in the map data.

First, the drawing determination means 63 determines whether the input map data includes surface data (step 1).
200). When it is determined that the surface data is included, the drawing determination unit 63 performs predetermined surface data drawing determination processing (step 1201). The surface data drawing determination process (step 1201) performed here is, for example, a process of determining an attribute predetermined for each surface data and selecting a required predetermined surface data.

When the processing relating to this surface data is completed,
The drawing determination means 63 then determines whether the input map data includes line data such as roads and line backgrounds (step 1202). When it is determined that the line data is included, the drawing determination means 63 performs a predetermined line data drawing determination process (step 1203). The line data drawing determination process (step 1203) performed here is, for example, a process of determining an attribute predetermined for each line data and selecting a required predetermined line data.

When the processing for this line data is also completed,
The drawing determination means 63 then determines whether the input map data includes character data (step 1204).
When it is determined that the character data is included, the drawing determination means 63
First, the rearrangement process is performed so that the coordinate values of the point where the drawing of the character string is started are arranged from the far side of the viewpoint to the vicinity of the viewpoint (step 1205).

Next, the drawing judging means 63 compares the height y of the point where drawing of each rearranged character string is started with the predetermined height h on the display screen (S). Step 1206). In this embodiment, the height h
Is a height of ⅔ from the bottom when the height of the display screen is 1, and is a predetermined constant value. This is because normally when the height from the bottom is ⅔ or more, the depression angle becomes very small and the density of nodes to be drawn becomes very high. However, this reference value (height h) may be set according to the height of the viewpoint or the like.

Further, the distance from the viewpoint may be used as a criterion for drawing a character string, instead of its height. For example, when the distance between the viewpoint and the destination is 1, only the character string whose distance from the viewpoint is 2/3 or less is drawn,
A character string having a distance longer than 2/3 may be deleted from the drawing target.

As a result of the position determination, the drawing judging means 63 makes the character string a drawing object if the height y of the point on the screen where the drawing of the character string is started is lower than the height h, and if it is high, the character string is drawn. Delete the string from the drawing target character string (step 12)
07). In this way, in the present embodiment, the graphics processing unit 49 draws the map data selected by the drawing determination unit 63 to prevent the bird's-eye view display from becoming complicated, and a clear and easy-to-see display is provided. Obtainable.

In the present embodiment, whether or not to draw a character string is determined based only on the displayed height. However, the priority of each character string is set in advance and the displayed height (or The priority range of the character string to be displayed may be determined according to the distance from the viewpoint, and only the character string with the priority included in the range may be drawn. For example,
The upper limit of the priority of the character string to be displayed is constant regardless of the height, and the lower limit of the priority of the character string to be displayed is set to be higher according to the height on the display screen. In the near area, only the character string with high priority is displayed, and in the area near the bottom of the display screen, not only the character string with high priority but also the character string with low priority is displayed. Therefore, when the current position is near the bottom of the display screen, the closer to the current position, the more detailed character information can be obtained, and the farther from the current position, the more important information is displayed. It is highly likely.

If attributes (character font of display characters, meaning contents of character strings, etc.) are set in advance for each character string, this attribute is used instead of the above priority and is set in advance for each area. You may make it display only the character of the specified attribute.

If a character string is defined at a predetermined point as the destination, only the character string may be displayed.

The above steps 1205-1207 are
It can be omitted, but it is preferable to execute it. The effect of these steps will be described with reference to FIGS. 13 and 14. Note that FIG. 13A shows steps 1205 to 1205.
FIG. 11 is a bird's-eye view obtained when drawing is performed without performing the rearrangement process and the drawing character string selection process of 1207. FIG.
FIGS. 14B and 14B are bird's-eye views obtained when the rearrangement process of step 1205 is executed and the drawing character string selection process of steps 1206 and 1207 is not performed. FIG. 14B is a bird's-eye view obtained according to the present embodiment, that is, a bird's-eye view obtained when the processing of steps 1205-1207 is executed. Note that FIG.
3 and FIG. 14, illustrations of figures drawn based on surface data and line data are omitted.

When the bird's-eye view display is performed without performing the rearrangement processing in step 1205, each character string is displayed according to the storage order of the character string, regardless of the distance from the viewpoint, as shown in FIG. , A character string far from the viewpoint may be overlaid and displayed on a character string near the viewpoint.

On the other hand, when the character string rearrangement processing in step 1205 is executed, as shown in FIG.
When the character string far from the viewpoint and the character string near the viewpoint overlap, the character string closer to the viewpoint is displayed over the character string farther from the viewpoint. The bird's-eye view displayed in this manner is preferable because the information closer to the current location can be easily read.

If the bird's-eye view is displayed without performing the drawing character string selection processing in steps 1206 and 1207,
As shown in FIG. 14A, the farther from the viewpoint, the smaller the depression angle from the viewpoint, so the compression is reduced, and the amount of data of lines, planes, and characters drawn per unit area increases. Since character data among these data is drawn on top of other data, lines and plane backgrounds are hidden by the drawn character data. In such a bird's-eye view, it is very difficult to read surface information such as roads, rivers, and green areas in the distance from the display screen.

On the other hand, in this embodiment, since the drawing character string selection processing of steps 1206 and 1207 is executed, as shown in FIG. 14B, the height from the bottom of the display screen is h.
Character data in the range up to (character drawing range) is drawn, and other character data is not drawn. Therefore, in the bird's-eye view drawn by the present embodiment, it is possible to easily read the surface information such as roads, rivers, and green areas far from the viewpoint on the display screen.

The bird's-eye view display device and navigation system of this embodiment can display a map represented by a bird's-eye view. Therefore, according to the present embodiment, the user can obtain a map display that is easy to see and in which the positional relationship of the points displayed in the map is easy to recognize. In addition to such effects, the present embodiment is considered to have the effects listed below.

First, in the present embodiment, the plane map display and the bird's eye view display can be arbitrarily switched. Therefore,
In this embodiment, both the plan view and the bird's-eye view can be displayed according to the user's request.

Secondly, in this embodiment, when the bird's-eye view display and the plan map display are switched, the angle formed by the plane projecting the map and the plane containing the map data is gradually increased or decreased in time series. That is, in this embodiment,
When converting between a flat map display and a bird's-eye view display, the viewpoint for obtaining a bird's-eye view moves smoothly. Therefore, in this embodiment, since the transition between the plan view and the bird's-eye view is smoothly performed, it is possible to easily recognize the correlation between the point displayed on the plan map and the point displayed on the bird's-eye map.

Thirdly, in the present embodiment, the viewpoint for obtaining the bird's-eye view can be fixed at a position which is always away from the current position in a certain direction and a certain distance, and the height of the viewpoint can be changed according to the operation input. Can be changed. If the viewpoint is fixed, the bird's-eye view is displayed so that the current position is always fixed at a certain point on the screen, so that the user can easily grasp the current position. Further, according to this embodiment, the viewpoint position can be set to a position desired by the user.

Fourth, in this embodiment, two points (for example,
When the positions of the present location and the destination are specified, the angle between the plane that projects the viewpoint and the map and the plane that contains the map data is determined so that the two points are displayed at the defined positions on the screen. , The bird's-eye view display is executed using the result. Therefore, according to the present embodiment, it is possible to easily determine the positional relationship between the two points. Also, even if the positions of the two points change, they are always displayed on the same screen,
The user can grasp the positional relationship between the two points without performing a complicated operation.

Fifth, the coordinate transformation means of this embodiment does not perform perspective transformation on character images. Therefore, in the present embodiment, all the characters included in the bird's-eye view are displayed upright with the same size, which is easy to read.

Sixth, the drawing determination means of this embodiment determines the character data position in the map data from the viewpoint according to the distance.
Sort character data strings. That is, a character string closer to the position from the viewpoint is treated as having a higher display priority. Therefore, in the present embodiment, the character data in the vicinity of the viewpoint is displayed without being lost because it is covered with another display, and thus it becomes easy to identify the character information close to the viewpoint.

Seventh, the drawing determination means of the present embodiment deletes the character string from the drawing target when the drawing height of the character string on the screen obtained as a result of the perspective transformation of the map is higher than a predetermined value. . Alternatively, the drawing determination means may delete the character string defined at a position more than a predetermined distance from the viewpoint from the drawing target. In this way, a character string is used for an area that is greater than or equal to a predetermined height or a predetermined distance, that is, when the bird's eye view is displayed, the depression angle is small and the amount of data drawn per unit area is very large. By not drawing, the road display, the surface background display, and the like in this area are not covered by the character string display. Therefore, in this embodiment, the bird's-eye view display does not hinder the recognition of the road and the like far from the viewpoint. .

[0135]

The bird's-eye view display device and the navigation system including the device of the present invention can display a map represented by a bird's-eye view. Therefore, according to the present invention, it is possible to obtain a map display that is easy to see and in which the positional relationship of points displayed in the map is easy to recognize.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a bird's-eye view display example of a map drawn according to the present invention.

FIG. 2 is a configuration diagram of a navigation system according to an embodiment.

FIG. 3 is a hardware configuration diagram of an arithmetic processing unit.

FIG. 4 is a functional block diagram of an arithmetic processing unit.

FIG. 5 is a functional block diagram of map drawing means.

FIG. 6 is an explanatory diagram showing perspective transformation of a map.

FIG. 7 is an explanatory diagram showing a coordinate conversion process for displaying a bird's-eye view.

FIG. 8 is a flowchart showing a processing flow of a coordinate conversion unit.

FIG. 9 is an explanatory diagram showing a method of setting a viewpoint and a projection surface for displaying a bird's-eye view.

FIG. 10 is an explanatory diagram showing a method of setting a viewpoint and a projection surface for displaying a bird's-eye view.

FIG. 11 is a flowchart showing the flow of perspective transformation calculation.

FIG. 12 is a flowchart showing a processing flow of a drawing determination unit.

FIG. 13 is an explanatory diagram illustrating an effect of a character string rearrangement process.

FIG. 14 is an explanatory diagram showing an effect of a drawn character string selection process.

FIG. 15 is an explanatory diagram showing a method of setting a viewpoint and a projection surface for displaying a bird's-eye view.

FIG. 16 is an explanatory diagram showing a method of setting a viewpoint and a projection surface for displaying a bird's-eye view.

FIG. 17 is an external perspective view of the navigation system according to the embodiment.

[Explanation of symbols]

1 ... Arithmetic processing unit, 2 ... Display, 3 ... Map storage device, 4 ... Voice input / output device, 5 ... Input device, 6 ... Wheel speed sensor, 7 ... Geomagnetic sensor, 8 ... Gyro, 9 ... GPS receiving device, 10 … Traffic information receiver, 21… CPU, 22
... RAM, 23 ... ROM, 24 ... DMA, 25 ... drawing controller, 26 ... VRAM, 27 ... color palette,
28 ... A / D converter, 29 ... SCI, 30 ... I / O device, 31 ... Counter, 41 ... User operation analysis means, 42
... Route calculation means, 43 ... Route guidance means, 44 ... Map drawing means, 45 ... Current position calculation means, 46 ... Map match processing means, 47 ... Data reading processing means, 48 ... Menu drawing means, 49 ... Graphics processing means , 61 ... Initial data clipping means, 62 ... Coordinate conversion means, 63 ... Drawing determination means, 64 ... Data clipping means, 65 ... Drawing command issuing means, 66 ... Scroll key, 67 ... Scale change key, 68 ... Projection angle change key , 69 ... Casing, 70 ... Touch sensor.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 16, 2002 (2002.5.1)
6)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Bird's eye view creation method, map display device and navigation system

[Claims]

5. An image display device, map storage means for holding map data for displaying a map, map drawing data created from the map data read from the map storage means, and drawing data for the map is created. In a map display device including map drawing means for displaying an image of a map on the image display device, the map data is character string data and the position of the character string.
Vector data for recognizing the
Image data for recognizing the image, the map drawing means includes coordinate conversion means for converting the coordinate data included in the map data, and the coordinate conversion means uses the determined position as a viewpoint, On the defined projection plane,
Perspective transformation of the coordinate data included in the above map data,
A map display device comprising perspective conversion means for creating drawing data of a bird's-eye view, wherein the perspective conversion is not performed on the image data of the map data.

6. An image display device, map storage means for holding map data for displaying a map, map drawing data created from the map data read from the map storage means, and drawing data for the map is created. and map drawing means for displaying an image of the map on the image display apparatus using, a current position recognizing section for recognizing the current position, the map data as a character string data, string position
Vector data for recognizing the
Image data for recognizing the image, the map drawing means includes coordinate conversion means for converting the coordinate data included in the map data, and the coordinate conversion means uses the determined position as a viewpoint, On the defined projection plane,
Perspective transformation of the coordinate data included in the above map data,
A perspective conversion means for creating drawing data of a bird's-eye view is provided , and the image data of the map data
Is a navigation system characterized by not performing the perspective transformation .

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation system for measuring the position of a moving body and notifying a user of the current position, and a map display device used in the system.

[0002]

2. Description of the Related Art In a navigation system mounted on a moving body, information from various sensors is arithmetically processed to measure the position of the moving body and display the position.

This navigation system uses a position measuring device for measuring the absolute position of a moving body and a two-dimensional vector obtained by projecting points on the ground such as roads and structures onto a plane obtained by mesh division by universal transverse Mercator projection. Required from a storage device that stores map data consisting of data and character data accompanying them, an input device that receives instructions from the outside, and a map mesh stored in the storage device according to instructions input from the input device And a display device that displays a map on the display by reading the vector data and converting the vector data.

Here, the data conversion processing includes movement conversion for changing the display position of the map, scale conversion such as enlargement / reduction used for displaying the map at an arbitrary scale, and rotation for changing the display direction of the map. There is conversion. By these processes, a plane map in which the ground is drawn by an orthogonal projection from directly above is displayed on the display.

[0005]

In the conventional navigation system, when the map is displayed, the ground map is displayed by orthographic projection from directly above. for that reason,
There is a problem that if two points that are distant from each other are displayed at the same time, the scale is inevitably increased and detailed information cannot be displayed.

Therefore, according to the present invention, when a plane (ground) is viewed obliquely from a viewpoint of an arbitrary height, a projection diagram projected on an arbitrary plane between the plane (ground) and the viewpoint is used. An object of the present invention is to provide a bird's-eye view creating method for expressing a map using a certain bird's-eye view, a map display device, and a navigation system including the device.

[0007]

In order to achieve the above object, the present invention is a bird's-eye view creating method for creating drawing data of a map represented by a bird's-eye view by using map data. A bird's-eye view creating method is provided, which is characterized in that the coordinate data included in the map data is perspective-transformed to create a bird's-eye view drawing data on a defined projection plane as a viewpoint.

In the bird's-eye view creating method of the present invention, the step of accepting the input of the position of the viewpoint, the coordinates of two predetermined points (for example, the current position and the destination) included in the map data, and the above-mentioned It is preferable that the projection plane is determined based on the input viewpoint position so that the drawing positions of the two points after the perspective conversion become predetermined positions.

Alternatively, the step of accepting an input of a scale factor, the coordinates of two predetermined points included in the map data, and the two points after the perspective transformation based on the input scale factor. The step of deciding the position of the viewpoint and the projection plane may be provided so that the drawing position becomes a predetermined position and the drawing scale becomes the input scale.

Further, a step of receiving an input of a projection angle which is an angle formed by the plane defined by the map data and the projection plane, based on the input projection angle and the determined viewpoint position, And the step of determining the projection plane.

Further, the present invention provides a map display device for displaying a bird's-eye view by using the above-mentioned bird's-eye view drawing method, and a navigation system for displaying a map by the map display device.

[0012]

In the bird's-eye view display device and the navigation system of the present invention, the map drawing means includes the coordinate conversion means, and the coordinate conversion means performs perspective conversion to convert and display the map in the bird's-eye view. Therefore, according to the present invention, the user can obtain a bird's-eye view map display that is easy to see and in which the positional relationship of points displayed in the map is easy to recognize. According to the bird's-eye view creation method of the present invention, the viewpoint position can be arbitrarily set, so that the needs of the user can be appropriately met.

It should be noted that a navigation system with better operability and convenience can be obtained by adopting a configuration that solves the following first to seventh problems.

First, when the processing speed of the scroll processing in the bird's-eye view display is slower than that in the plane display, the operability is poor when the scroll processing is frequently used to search a predetermined point in the bird's-eye view display. It may become.

Therefore, in the present invention, it is desirable that the two-dimensional map display and the bird's-eye view display can be arbitrarily switched. By doing this, it is possible to display both the plan view and the bird's-eye view according to the user's request,
The convenience is improved.

In such a case, there is a second problem that it becomes difficult for the user to grasp the positional relationship when switching between the planar map display and the bird's-eye view display. This is because the point of view of the map changes,
This is because the position at which a certain point is displayed on the screen changes significantly, and a point that has not been displayed until now is displayed or not displayed.

Therefore, in the present invention, when it is possible to switch between the plan view display and the bird's-eye view display, at the time of switching between the bird's-eye view display and the plan map display, the angle between the plane projecting the map and the plane containing the map data is set. It is desirable to gradually increase or decrease over time. That is,
In the present invention, it is desirable that the viewpoint for obtaining the bird's-eye view moves smoothly in the conversion between the planar map display and the bird's-eye view display. In this way, since the transition between the plan view and the bird's-eye view is smoothly performed, it is possible to easily recognize the correlation between the point displayed on the plan map and the point displayed on the bird's-eye map.

Thirdly, when a map is displayed in a bird's-eye view, if the viewpoint position, which is a parameter of perspective transformation, is fixed, the position of displaying the mark of the current position displayed on the screen moves as the current position moves. However, there is a problem that the mark of the current position is not displayed when it deviates from the displayed map area.

Therefore, in the present invention, the viewpoint for obtaining the bird's-eye view can be always fixed at a position away from the current position in a certain direction and a certain distance. Also, the height of the viewpoint can be changed according to the operation input. If the viewpoint is fixed as described above , the bird's-eye view is displayed so that the current position is always fixed at a certain point on the screen, so that the user can easily grasp the current position.
Further, if the viewpoint position can be set to a position desired by the user, convenience is improved.

Further, when it is attempted to display two certain points on the same screen, the scale may be updated according to the distance between the two points in the conventional planar map display, but only the scale is updated in the bird's eye view display of the map. Then, there is a fourth problem that the map cannot be displayed optimally.

[0021] In the present invention, two points (e.g., current location and the destination) receives designation of position of the viewpoint so that the two points are displayed in a defined position on the screen,及<br/> Alternatively , the angle formed between the plane onto which the map is projected and the plane including the map data may be determined, and the bird's-eye view display may be executed using the result. By doing so, the positional relationship between the two points can be easily determined. Further, even if the positions of the two points are changed, they are always displayed on the same screen, so that the user does not have to perform complicated operations.
You can understand the positional relationship between points.

Further, in the present invention, the line background of roads and railroads, the surface background of rivers and green areas, and character strings are perspective-transformed and drawn when displaying a bird's-eye view. However, when perspective transformation strings, small shape perspective distant character, and distortion, One <br/> side, perspective vicinity of characters it may become difficult to read the string will be the expansion of the 5 There's a problem.

Therefore, it is desirable that the coordinate conversion means of the present invention does not perform perspective conversion for character images. By doing so, the characters included in the bird's-eye view are displayed upright in the same size, which makes it easier to read the character string.

Further, when displaying a lot of character data, the character strings are displayed overlapping each other. Particularly, in the bird's-eye view, since the depression angle from the viewpoint is small in the distance from the viewpoint, the reduction rate is large and the character data displayed per unit area is large. Therefore, in the bird's-eye view, there is a sixth problem that character data and character data are likely to overlap each other at a distance from the viewpoint.

Therefore, the drawing determination means of the present invention, the closer the character data position in the map data is from the viewpoint,
It is desirable to give higher priority to the display of the character data. In this way, by displaying the one with the higher priority over the one with the lower priority, it is possible to prevent the character string from being lost and make the reading easier.

When the current position is near the bottom or near the viewpoint, it is preferable that the displayed height or the distance from the viewpoint is used as a reference for this priority. When there are two or more character strings that are displayed in an overlapping manner, the lower the displayed height (height from the bottom of the display screen) (or the closer the distance from the viewpoint), the higher the priority (that is, other characters). If it is displayed so as not to be covered by a column and overlaid on another character string), the character data in the vicinity of the current position is displayed without being lost by being covered by another display. Therefore, in this way, it is possible to prevent the loss of character information near the current location that the user may desire, and it becomes easy to read the character string.

As described above, when the bird's-eye view display is performed, a large amount of line data, surface background data, and character data are drawn per unit area in a region far from the viewpoint (a region with a small depression angle). Therefore, when drawing character data of these data over other data,
In the area far from the viewpoint, since the line data and the surface background data are covered by the character data, there is a seventh problem that it may be difficult to read the shape of the road or the like far from the viewpoint.

Therefore, if the drawing height of the character string on the screen obtained as a result of the perspective transformation of the map is higher than a predetermined value, the drawing judging means of the present invention preferably deletes it from the drawing object. . Alternatively, the drawing determination means, for a character string defined at a position more than a predetermined distance from the viewpoint,
It may be deleted from the drawing target. in this way,
Do not draw a character string in an area that is more than a certain height or more than a certain distance, that is, in the bird's-eye view display, the depression angle is small and the amount of data drawn per unit area is very large. By doing
The road display and the surface background display in this area are not covered by the character string display. Therefore, in this way, there is an advantage that the recognition of roads and the like far from the viewpoint is not disturbed even if the bird's-eye view display is performed.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a bird's-eye view map displayed by the bird's-eye view map display device installed in the navigation system of this embodiment. The bird's-eye view display device of this embodiment creates a bird's-eye view 102 showing a bird's-eye view from a specific position as a projection view of two-dimensional map data (shown as 101 in FIG. 1) and displays it on the display screen of the display 2. In addition,
In the bird's-eye view 102 shown in FIG. 1, the route 104 is highlighted to show the route (in FIG. 1, the line is thickened to make the line thicker, but it is highlighted by blinking or discoloring. Good). The mark 105 is a symbol for indicating the current position. Further, in FIG. 1, the arrow indicates 2
The projection relationship from the three-dimensional map data 101 to the bird's-eye view 102 is shown.

FIG. 17 is an external perspective view of the mobile body navigation system of this embodiment. The navigation system of the present embodiment is housed in a housing 69, and the housing 69 has a display screen of the display 2 and a scroll key 66.
A scale change key 67, a projection angle change key 68, and a touch panel 70 provided on the display screen of the display 2.
And so on.

The scroll key 66 is a key for accepting a scroll instruction of an image displayed on the display screen, and includes four direction designation keys 660 for accepting a scroll instruction of up, down, left and right. The scale change key 67 is a key for accepting a change in the scale of the map displayed on the display screen, and includes two scale specifying keys 67a, 67b for accepting enlargement and reduction, respectively. The projection angle change key 68 is a key for accepting the designation of the angle of the projection surface of the bird's-eye view displayed on the display screen, and is provided with two angle designation keys 68a, 68b for accepting the rise and fall of the projection angle, respectively. . The touch panel 70 is an input unit that detects a touch on the surface of the touch panel 70 and outputs the touched position.

As shown in FIG. 2, the mobile navigation system according to the present embodiment includes an arithmetic processing unit 1 and a display 2 connected to the arithmetic processing unit 1 via a signal line S1.
A map storage device 3 connected to the arithmetic processing unit 1 via a signal line S2, a voice input / output device 4 connected to the arithmetic processing unit 1 via a signal line S3, and a signal to the arithmetic processing unit 1 Line S
4, an input device 5 connected to the arithmetic processing unit 1, a wheel speed sensor 6 connected to the arithmetic processing unit 1 via a signal line S5, and a geomagnetic sensor connected to the arithmetic processing unit 1 via a signal line S6. 7, a gyro 8 connected to the arithmetic processing unit 1 via a signal line S7, a GPS (Global Positioning System) receiving device 9 connected to the arithmetic processing unit 1 via a signal line S8, and the arithmetic processing The traffic information receiving device 10 is connected to the section 1 via a signal line S9. In addition, each signal line S
1 to S9 may be wired or wireless as long as they can transmit a signal, but a wired line is used in this embodiment.

The arithmetic processing unit 1 detects the current position based on the information output from the various sensors 6 to 9, and reads necessary map information from the map storage device 3 based on the obtained current position information. , Develop map data as graphics, display the current location mark on it , select the optimum road connecting the destination and the current location instructed by the user, and inform the user using voice or graphic display, etc. It is a central unit that performs various processes such as.

The display 2 is a unit for displaying the graphics information generated by the arithmetic processing unit 1, and is a CRT.
And a liquid crystal display. In addition, S1 between the normal arithmetic processing unit and the display is the RGB (Red Green Blue) signal or N in this embodiment as well as the normal system.
Connect with a TSC (National Television System Committee) signal.

The map storage device 3 is a CD-ROM (Compac
t Disk-Read Only Memory) and IC (Integrated Circ)
uit) A large-capacity storage medium such as a card, and a reading process for reading data held in the large-capacity storage medium and notifying the data to the arithmetic processing unit 1 in response to a request from the arithmetic processing unit 1. A writing process is performed to store the data notified by No. 1 in the mass storage medium.

Further, the voice input / output device 4 includes an arithmetic processing unit 1
The message generated to the user is converted, the voice is output, the voice input is accepted, the content is recognized, and the process is transferred to the arithmetic processing unit 1.

The input device 5 is a unit that receives an instruction input from the outside, and in the present embodiment, the scroll key 66, the scale change key 67, and the projection angle change key 6 described above.
8 and a touch panel 70. The configuration of the input device 5 is not limited to this, and other input means such as a joystick, a keyboard, a mouse, and a pen input device may be used.

As a sensor used to detect a position in mobile navigation, the navigation system of this embodiment measures the distance from the product of the wheel circumference and the measured wheel rotation speed, and further The wheel speed sensor 6 that measures the angle at which the moving body bends from the difference in the number of rotations of the wheels, the geomagnetic sensor 7 that detects the magnetic field held by the earth and the direction in which the moving body is facing, and the moving body A gyro 8 composed of an optical fiber gyro, a vibration gyro, etc., which measures the angle of rotation, and a signal from a GPS satellite is received, and the distance between the mobile body and the GPS satellite and the rate of change of distance are 3 or more GPS receiver 9 for measuring the current position, traveling direction and traveling direction of the moving body by measuring with respect to
Equipped with.

Further, the navigation system of the present embodiment is equipped with a traffic information receiving device 10 for receiving signals from beacon transmitters and FM broadcasts that issue traffic information such as road congestion, construction, road closure information and parking lot information. .

The hardware configuration of the arithmetic processing unit 1 described above is shown in FIG. The arithmetic processing unit 1 is a CPU that executes processing such as numerical calculation and control of each device 22 to 31.
(Central Processing Unit) 21 and RAM (Random Access Memory) 2 for holding maps and calculation data
2 and ROM (Read OnlyM) for holding programs
emory) 23 and high-speed memory-between memory and memory-
DMA (Direct M) that executes data transfer between each device
emory Access) 24, a drawing controller 25 that executes graphics drawing at high speed such as expanding vector data into an image, and performs display control, and a VRAM (Video Random A) that stores graphics image data.
ccess Memory) 26, a color palette 27 that converts image data into RGB signals, and an A / D (Analog / Digital) converter 28 that converts analog signals into digital signals.
And an SCI (Serial Communication Interface) 29 for converting a serial signal into a parallel signal synchronized with the bus.
And I / O that is placed on the bus in synchronization with the parallel signal
An (Input / Output) device 30 and a counter 31 for integrating a pulse signal are provided. These devices 21-31
Are connected to each other by a bus.

Next, the functional configuration of the arithmetic processing unit 1 will be described with reference to FIG. The arithmetic processing unit 1 includes a user operation analysis unit 41, a route calculation unit 42, and a route guidance unit 43.
, Map drawing means 44, current position calculation means 45, map matching processing means 46, and data reading processing means 4
7, a menu drawing means 48, and a graphics processing means 49. Each of these means 41 to 49 is an RO
It is realized by the CPU 21 executing the instruction held in M23.

The current position calculating means 45 is composed of the wheel speed sensor 6
By using the distance data and the angle data obtained as a result of integrating the distance pulse data measured by the gyro 8 and the angular acceleration data measured by the gyro 8, by integrating the data on the time axis, the initial position (X , Y), the processing for calculating the position (X ′, Y ′) after traveling of the mobile body is performed. Here, the current position calculation means 45 corrects the absolute azimuth of the direction of travel from the azimuth data obtained from the geomagnetic sensor 7 and the angle data obtained from the gyro in order to match the relationship between the rotated angle of the moving body and the direction of travel. . When the data obtained from the sensor is integrated as described above, the error of the sensor accumulates. Therefore, the current position calculation means 45
Based on the position data obtained from the GPS receiving device 9, a correction process of canceling the accumulated error is performed at a predetermined time period (every 1 second in this embodiment), and this current position information is obtained. Output the corrected data.

The current position information thus obtained still contains a minute error due to the sensor. Therefore, in order to further improve the position accuracy, in the navigation system of the present embodiment, the map matching processing means 46 performs the map matching processing. This is the road data included in the map around the current location read by the data reading processing means 47 and the current position calculating means 4
This is a process of comparing the traveling loci obtained from No. 5 with each other and fitting the current position to the road having the highest shape correlation. By performing the map matching process, the current location will often coincide with the road on which the vehicle is traveling, so that the current location information can be accurately output.

On the other hand, the user operation analysis means 41 analyzes the request contents of the operation instruction received via the input device 5, and the respective units 42 to 4 are executed so that the corresponding processing is executed.
Control eight. For example, when a route guidance request to a destination is input, the map drawing means 44 is requested to display a map for setting the destination, and then a process for calculating a route from the current location to the destination is performed. It operates so as to request the calculation means 42 and the route guidance means 43 to perform processing for presenting route guidance information to the user.

The route calculation means 42 searches for a node connecting two designated points using the Dijkstra method or the like, and obtains the route having the highest priority. The path calculation unit 42 has a plurality of priority order criteria, and uses the criteria specified by the operation instruction to determine the path. In the present embodiment, a route that minimizes the distance between two points, a route that can be reached in the shortest time, a route that costs the least, and the like are required according to the operation instruction.

The route guide means 43 is provided with the link information of the guide route obtained by the route calculation means 42 and the current position calculation means 4.
5 and the current position information obtained by the map match processing means 46 are compared, and whether or not to go straight before passing an intersection or the like,
Voice input / output device 4 provides direction information such as whether to turn left or right.
To output as voice, or draw a direction to proceed on the map displayed on the display screen of the display 2.

The data reading processing means 47 operates so as to prepare for reading the map data of the requested area from the map storage device 3. The map drawing means 44 receives the map data around the point designated for display from the data reading processing means 47 and draws the designated object at the designated scale and in the designated direction in the upward direction. To the graphic processing means 49.

On the other hand, the menu drawing means 48 operates so as to receive the command output from the user operation analyzing means 41 and transfer the commands for drawing various kinds of required menus to the graphic processing means 49.

The graphics processing means 49 receives the drawing commands generated by the map drawing means 44 and the menu drawing means 48 and develops an image in the VRAM 26.

Next, the function of the map drawing means 44 will be described with reference to FIG. The map drawing means 44 includes an initial data clipping means 61, a coordinate converting means 62, and a drawing determining means 6
3, data clip means 64, and drawing command issuing means 6
5 and 5.

The initial data clipping means 61 uses the respective meshes of the map data fetched from the map storage device 3 by the data reading processing means 47 to extract road data, plane and line background data, and character data relating to areas required for subsequent processing. Is selected by the clip processing, and the result is notified to the coordinate conversion means 62. In the present embodiment, the initial data clip means 61 is activated every 0.5 seconds. It is also activated by an operation instruction notification from the user operation analysis means 41.

As a clip processing algorithm used here, for road data and line data, Cohen-
The Sutherland line clipping algorithm and the Surface-Hodgman polygon clipping algorithm for surface data are available (Foley, van Da
m, Feiner, Hughes: Computer Graphics: Addison-We
sley Publishing Company pp.111-127). By this processing, it is possible to reduce the amount of data that should be subjected to the subsequent coordinate conversion and drawing processing, and therefore it is expected to speed up.

The coordinate conversion means 62 is used for enlarging / reducing, rotating, projecting, etc. the map data obtained by the clipping process.
The process of converting each coordinate value of the map data is performed. The coordinate conversion means 62 is activated in response to the notification from the initial data clipping means 61 or the user operation analysis means 41.

The drawing determination means 63 functions to select the data that needs to be actually drawn from the map data obtained by the coordinate conversion means 62. For example, the drawing determination means 63
When the scale becomes large, the amount of data to be drawn is substantially increased, so that the operation is performed so as to delete a narrow road or an optional place name. This makes it possible to prevent the processing speed for drawing from becoming extremely slow. The drawing determination means 63 is the coordinate conversion means 62 or the user operation analysis means 4.
It is activated in response to the notification from 1.

The data clipping means 64 operates so as to select map data relating to the drawing area from the map data obtained by the drawing judging means 63 by clipping processing. As the clip processing algorithm used here, the same algorithm as the initial data clipping means can be used. The data clip means 64 is activated in response to the notification from the drawing determination means 63 or the user operation analysis means 41. The data clip means 64 may be omitted.

The drawing command issuing means 65 draws roads, planes and lines, background data, character data, etc. included in the map data obtained by the data clipping means 64 in a specified color or pattern, so that lines and polygons are drawn. , A command for drawing a character or the like and a command for setting a color or a pattern are issued to the graphics processing means 49. The drawing command issuing means 65 is activated in response to the notification from the data clip means 64.

In this embodiment, the initial data clipping means 6
1 is activated every 0.5 seconds and notifies the coordinate conversion means 62 of the data obtained as a result of the clip processing. Therefore,
In this embodiment, except for the case of an operation instruction from the outside,
Drawing will be performed every 0.5 seconds.

Next, the outline of the bird's-eye view display will be described with reference to FIG. In the printed atlas and the conventional navigation system, when the map is displayed, it is represented by a plane map display in which the map is viewed from the point at infinity from the ground. The planar map display has an advantage that the scale is constant within the same screen regardless of the location, and thus it is easy to grasp the sense of distance. But,
When trying to display a certain two points on the same screen, it is necessary to perform an operation to adjust the scale of displaying the map to the optimum, and it is possible to display them at a time if the distance between the two points is large. Since the amount of information is limited by the size and definition of the display, there is a drawback that only limited information can be displayed. There is a bird's-eye view display as a means for solving this problem.

The bird's-eye view display is two-dimensional or three-dimensional on the plane A.
The dimensionally map information 5 3, it is implemented by the perspective transformation that is projected on a plane B that forms a plane A phrase angle θ obtain projection view information 5 4. In the conceptual diagram shown in FIG. 6, coordinates (T
A map 53 (point a, point b, point c, point d) is represented by a rectangle with a point 55 of (x, Ty, Tz) as a viewpoint and is represented by a rectangle on a plane A (illustrated as a rectangle 51). Is projected onto a plane B (illustrated as a quadrangle 52) forming an angle θ with the plane A, and is represented by a quadrangle having projections 54 (points a ′, b ′, c ′, and d ′ as vertices). Is shown). Here, point a, point b, point c, and point d on the map 53 are point a ′, point b ′, point c ′, and point a, respectively.
It is projected at point d '. In the present specification,
In the projection process, the viewpoint 55, which is the origin of the viewpoint coordinate system,
We simply call it "viewpoint". In the present specification, simply referring to “viewpoint” does not mean “viewpoint” as the position of the user's eyes.

When the bird's-eye view representation is performed, information of a portion near the viewpoint 55 (for example, straight line ab) is enlarged, and information of a portion far from the viewpoint (for example, straight line cd) is reduced and expressed.
As a result, when displaying two points on the same screen, the point for which more detailed information is to be obtained is near the viewpoint, the other is far from the viewpoint, and the two points are displayed on the same screen. It becomes possible to express the mutual positional distances in an easy-to-understand manner and to provide the user with a larger amount of information near the viewpoint.

In this embodiment, since it is possible to use two-dimensional map data as the map information used for the bird's-eye view display, by adding a means for performing such perspective transformation to the conventional navigation system, A bird's-eye view display can be realized without adding a large amount of map data. In the present embodiment, the perspective transformation is executed by the coordinate transformation means 62. In order to realize the bird's-eye view display, it is desirable to make various efforts as described later.

First, a method of realizing a basic bird's-eye view display will be described with reference to FIG. First, the coordinate conversion means 62
Determines the position of the viewpoint, determines which direction to view from the viewpoint position, and the angle of the projection plane (illustrated as angle θ in FIG. 6) (step 1). As a result, the area to be displayed in the bird's-eye view is determined. When a bird's-eye view is displayed on a rectangular display screen, the area near the viewpoint is narrow and the area far from the viewpoint is wide. Therefore, the finally drawn map data becomes the trapezoidal area 72 in the map mesh 71.

Next, the coordinate conversion means 62 uses the initial data clipping means 61 to draw the trapezoidal area 7 actually drawn from the map mesh data 71 including the area to be displayed in the bird's-eye view.
The map data of the rectangular area 73 circumscribing 2 is extracted (step 2).

Next, the coordinate conversion means 62 enlarges or reduces the extracted data and then performs an affine transformation to make the trapezoid erect, and then further performs perspective transformation to convert each coordinate value of the map data into the data. Convert (step 3).
At this time, the coordinate transformation by the affine transformation is performed on the plane A.
Is the angle between the plane B and the plane B, the map data coordinate value before conversion is (x, y), and the map data coordinate value after conversion is (x ',
y ′), it is expressed by the following (Equation 1).

◎

[Equation 1]

In the coordinate conversion in the perspective processing at this time, the position coordinates of the viewpoint are (Tx, Ty, Tz), and the plane A is used.
Is the angle between the plane B and the plane B, the map data coordinate value before conversion is (x, y), and the map data coordinate value after conversion is (x ',
y ′) is expressed by the following (Equation 2) and (Equation 3).

◎

[Equation 2]

◎

[Equation 3]

In step 3, the drawing target area which was the trapezoid 72 at the time of step 2 is converted into the rectangular area 74, and the rectangle 73 circumscribing the trapezoid 72 is coordinate-converted into the rectangle 75 circumscribing the rectangle. Here, it is not necessary to draw the portion outside the drawing target area 74 in the area within the rectangle 75. Therefore, the coordinate conversion means 62 uses the data clipping means 64 to clip and remove the area outside the rectangular area 74 to be drawn (step 4).

The map data thus obtained is notified to the drawing command issuing means 65. Drawing command issuing means 6
5 uses the notified map data to generate a drawing command and causes the graphics processing means 49 to create drawing data. The graphics processing means 49 creates drawing data, stores it in the VRAM 26, and instructs the display 2 to display. The display 2 displays the drawing data held in the VRAM 26 on the display screen. As a result, the bird's-eye view map 102 as shown in FIG. 1 is displayed on the display screen of the display 2.

By using the bird's-eye view display, it is easy to recognize the azimuth and positional relationship between any two points. Furthermore, the bird's-eye view display is suitable for providing detailed information around a certain point and providing general information around another point. In this way, when providing detailed information or outline information around a specific point, the coordinates of the specific point may be set in advance, or the position can be determined by obtaining the coordinates that satisfy the predetermined conditions. May be defined, and the input of the position of the point may be accepted.

In the navigation system, the current location is often selected as one of the points. The position information of the present position is obtained from the present position calculating means 45 or the map matching processing means 46. Therefore, when the current position is designated to either the detailed information display point or the general information display point via the input device 5, the map drawing means 44 obtains from the current position calculation means 45 or the map match processing means 46. Use the coordinates of the current location.

However, in the case where the designation of the position on the map displayed on the display screen is accepted as either the detailed information display point or the general information display point, the user selects the point for displaying the detailed information or the general information. You often have to scroll through the map to find it. However, in the bird's-eye view display, the scroll speed is slow because it is necessary to redraw the entire surface every time the display area is changed. Therefore, there is a problem in that the operation of varying the scroll display is inconvenient.

In order to solve this problem, in this embodiment,
In the coordinate conversion, the processing shown in FIG. 8 is performed.

First, if it is necessary to enlarge or reduce the map (step 1000), the coordinate conversion means 62 performs enlargement or reduction calculation on the region to be processed (step 1010), and it is necessary to rotate the map. Ba (Step 1
020) and rotation conversion processing (step 1030). The rotation conversion process (step 1030) includes a rotation angle calculation (step 1031) and an affine conversion calculation (step 1032).

Next, the coordinate conversion means 62 determines whether or not the bird's-eye view display is performed (step 1040). here,
For example, when an instruction to search for an arbitrary point on the map is input via the input device 5 or when an instruction to display a plan view is input via the input device 5, the coordinate conversion means 62 is a bird's-eye view display determination (step 1040)
In, it is determined that the perspective transformation is not performed, and the perspective transformation processing (step 1050) is not executed, and the coordinate transformation processing ends. In this case, since the perspective conversion process is not executed,
A plane map is displayed on the display screen of the display 2.

According to the present embodiment, in the operation of searching for an arbitrary point in the map, the map is displayed not as a bird's-eye view but as a planar map, so that the target point can be quickly searched for.

Further, for example, when a bird's-eye view display instruction is input through the input device 5 or when an arbitrary point is designated as a destination through the input device 5 during the plan view display, etc. Then, the coordinate conversion means 62 that has received those instructions via the user operation analysis means 41 performs step 104.
In the bird's-eye view display determination at 0, it is determined that perspective conversion is required, and perspective conversion processing (step 1050) is executed.

This perspective conversion process (step 1050) includes a projection angle calculation (step 1051), a projection surface position calculation (step 1052), and a perspective conversion calculation (step 1053). As a result, the map data notified to the drawing command issuing means 65 is converted into the bird's-eye view, and therefore the graphics processing means 49.
The drawing data created by and stored in the VRAM 26 is also a bird's-eye view. Therefore, the map displayed on the display 2 is also switched from the plan view to the bird's-eye view.

As described above, the bird's-eye view can be arbitrarily switched to the plan view and the plan view can be arbitrarily switched to the bird's-eye view. Therefore, according to the present embodiment, an easy-to-understand map representation can be provided.

[0081] Also, an instruction switch, or switching from the bird's-eye view to the planimetric map on the screen switch to the bird's-eye view from the plane map generated in the above-mentioned process or from a user via a input device 5, the bird's-eye view display from the plane map display In such a case, if the two-dimensional map and the bird's-eye view are immediately switched, the map representation on the screen changes significantly, and it becomes difficult for the user to recognize the map. Therefore, it is desirable that the transition between the plan view and the bird's-eye view be gradually performed.

In this embodiment, when the screen is switched from the planar map to the bird's-eye view, the projection angle θ is calculated in the perspective conversion process (step 1050) (step 105).
In 1), the projection angle θ is gradually increased (every 0.5 seconds in this embodiment) from 0 ° over time (by 5 ° in this embodiment), and increased when the target projection angle is reached. To make it stop. At this time, the unit of the projection angle to be increased may be a constant value.

As described above, since the projection angle is increased with time and the perspective transformation calculation (step 1053) is performed, the plane map smoothly changes to the bird's-eye view. Therefore, the user can change the position of the point displayed on the plane map and the bird's-eye view. You will be able to easily understand the relationship. Even when the bird's-eye view is switched to the planar map, the same effect as described above can be obtained by gradually decreasing the projection angle that was initially set to 0 degrees in time series.

Next, the angle θ (projection angle) formed by the map and the projection plane, which is the perspective transformation parameter in the bird's-eye view display, and the viewpoint coordinate system including the projection plane viewed from the object coordinate system including the map plane. Origin coordinates (Tx, Ty, Tz),
That is, a method of determining the position of the projection surface will be described with reference to FIGS.

In the navigation system, it is generally desired that the point where the user is currently traveling, that is, the vicinity of the current location is displayed in detail. Therefore, first, as shown in (c) of FIG. 9, a case will be described in which a bird's-eye view display is performed so that the current position is located on the lower side of the center of the screen. In this case, a bird's-eye view is displayed on the screen in front of the traveling direction as viewed from the current location and the road map that has been traveled so far. It should be noted that FIG. 9A shows a field of view (range displayed and displayed) 92 in the map mesh 91, and FIG. 9B shows a viewpoint position and a projection angle for obtaining a bird's-eye view. Also, FIG. 9 (c)
Fig. 2 shows the current position and traveling direction in the obtained bird's-eye view display. In addition, in FIG. 9, a dotted arrow indicates a traveling direction.

In order to realize the bird's-eye view display as shown in FIG. 9C, the coordinate conversion means 62 first executes the necessary enlargement / reduction processing (steps 1000 and 101).
0), determine that rotation is required (step 1020),
As shown in FIG. 9A, an angle φ formed by the traveling direction vector and the bottom of the map mesh is obtained (step 1031), and affine transformation of rotating the map data by the angle φ is performed on each coordinate value. (Step 1
032).

Since it is determined in step 1040 that the bird's-eye view is displayed, the coordinate conversion means 62 executes a process of calculating the projection angle θ and the viewpoint position (step 1051).
And 1052).

If the projection angle θ is set in the vicinity of 0 °, for example, the difference in scale between the vicinity of the viewpoint and the distance from the viewpoint becomes small,
If it is set in the vicinity of 90 °, the difference in scale between the vicinity of the viewpoint and the distance from the viewpoint becomes large. In this embodiment, the projection angle θ is usually set to about 30 ° to 45 °.

In this embodiment, the coordinate conversion means 62
Is an angle change direction instruction (input by the projection angle change key 68) notified from the user operation analysis means 41.
The projection angle θ is changed according to. That is, when the user operation analysis unit 41 detects that the angle instruction key 68a indicating the elevation is pressed, the user operation analysis unit 41 issues an instruction to raise the projection angle to the coordinate conversion unit 6.
Notify 2. Further, each time it detects that the pressing has continued for 0.5 seconds from the notification of the projection angle increasing instruction, the coordinate converting means 62 is notified of the projection angle increasing instruction. The coordinate conversion unit 62 that has received the notification of the rising instruction increases the projection angle θ by 5 ° (that is, increases the projection angle by 5 °). Further, the same is true for the instruction to lower the projection angle, and the depression of the angle instruction key 68b indicating the lowering and 0.
Each time the operation is continued for 5 seconds, the user operation analysis unit 41 notifies the coordinate conversion unit 62 of a projection angle lowering instruction, and the coordinate conversion unit 62 that receives the instruction decreases the projection angle θ by 5 ° (that is, projection). Decrease the angle by 5 °).

By doing so, in this embodiment, the user can arbitrarily set the map area to be displayed in the bird's-eye view map display. In this way, when the increase of the projection angle is instructed, the projection angle θ is increased, so that a farther map is displayed. When the projection angle is decreased, the projection angle θ is decreased when operated, so that the map near the current position is displayed.

Next, the coordinate converting means 62 subtracts the position (Tx, Ty, Tz) of the projection surface from the present position (x, y, z) by subtracting the position (Tx, Ty, Tz) of the projection surface. (Δ
x, Δy, Δz) is always calculated to be a constant value (step 1052). Further, the coordinate conversion means 62 has an absolute value of 0 for Δx, and a small value for Δz when displaying at a small scale corresponding to the scale at which the map is displayed at Δz.
When displaying at a large scale, set a large value for Δz. Normally, Δz should be selected so that the scale of the plan view and the scale of one point near the center of the bird's eye view display match.

It is desirable that the scale of the map can be changed according to the user's request. Therefore, in the present embodiment, the coordinate conversion means 62 changes the scale of the displayed map in accordance with the scale change instruction (input by the scale change key 67) notified from the user operation analysis means 41. That is, the user operation analysis means 41 uses the enlargement instruction key 67a.
When the press of is detected, the enlargement instruction is notified to the coordinate conversion unit 62. Also, the pressing is 0.5 from the notification of this enlargement instruction.
Each time it detects that the second has been continued, the coordinate conversion means 62
Notify to the enlargement instruction. Upon receiving the notification of the enlargement instruction, the coordinate conversion unit 62 increases Δz by a predetermined value in step 1052. The same applies to the reduction instruction. Every time the reduction instruction key 67b is pressed and 0.5 seconds is continued, the user operation analysis unit 41 notifies the coordinate conversion unit 62 of the reduction instruction and receives the coordinate conversion. Means 6
2 reduces Δz by a predetermined value in step 1052.

In the present embodiment, Δy can take a negative value as shown in FIG. 9, but it can also take a positive value as shown in FIG. In this embodiment, the bird's-eye view display can be performed without any problem regardless of whether the viewpoint position is in front of or behind the current position. Note that FIG. 15 is an explanatory diagram for obtaining a bird's-eye view of different viewpoints in the same range as that shown in FIG. 9. FIG. 15A shows a field of view (range displayed and displayed) 152 in the map mesh 151.
5 (b) shows a viewpoint position and a projection angle for obtaining a bird's-eye view. Further, FIG. 15C shows the position and the traveling direction of the current position in the obtained bird's-eye view display. In addition, in FIG. 15, a dotted arrow indicates a traveling direction.

In this embodiment, the coordinate conversion means 62 determines the position of the viewpoint (specifically, Δy) according to the viewpoint position (input by the touch sensor 70) notified from the user operation analysis means 41. decide. That is, when the user operation analysis unit 41 detects a contact with the touch sensor 70, the user operation analysis unit 41 notifies the coordinate conversion unit 62 of the contact position. Upon receiving the notification of the position information, the coordinate conversion means 62 performs step 10
At 52, Δy so that the viewpoint is at the notified position
To set.

As described above, in this embodiment, Δy can be set to an arbitrary value in a wide range from positive to negative in accordance with a user's instruction. Therefore, according to the present embodiment, the position to be displayed in detail can be flexibly set.

Finally, the coordinate conversion means 62 uses the projection angle θ and the position (Tx, T) of the projection surface thus obtained.
y, Tz) is used to perspectively transform each coordinate value of the map data (step 1053). By the graphics processing means 49 performing drawing processing using the obtained map data,
In the bird's-eye view display of the maps shown in FIGS. 9C and 15C, the traveling direction is always upward, and the current position is displayed at the same point on the screen.

In the navigation system, it is desired to display in detail the point where the user is currently traveling, that is, the vicinity of the current location. Therefore, as described above, in the navigation system of the present embodiment, FIG.
As shown in (c), FIG. 15 (c) and FIG. 16 (c), the current location is displayed on the lower side of the center of the screen.

In the navigation system of this embodiment,
The designation of the destination can be accepted through contact with the touch panel 70. When the destination is designated, the navigation system of the present embodiment draws the destination so that it is included in the visual field (range drawn on the display screen).
At this time, the coordinate conversion means 62 causes the current position to be on the lower side of the center of the screen and the destination to be on the upper side of the center of the screen as described above (shown in FIGS. 10C and 16C). ), Determine the rotation angle φ.

A bird's-eye view display method in this case is shown in FIG.
This will be described with reference to FIGS. 10 and 16. 10 is an explanatory diagram for obtaining a bird's-eye view in which both the present location and the destination are drawn on the same screen (field of view), and FIG. 16 is illustrated in FIG.
It is explanatory drawing in the case of obtaining the bird's-eye view of a different viewpoint of the same range as what was shown in FIG. 10 (a) and 16
FIG. 10B and FIG. 16 show a field of view (range displayed and displayed) 162 in the map mesh 161 in FIG.
A viewpoint position and a projection angle for obtaining a bird's-eye view are shown in (b). Further, FIGS. 10C and 16C show the positions of the current position and the destination in the obtained bird's-eye view display.
The dotted arrows in FIGS. 10 and 16 represent the direction of the destination.

[0100] Here, the lower center of the screen is the current position,
The case of displaying the upper center of the screen as the destination will be described as an example. However, when receiving the designation input of any two points and displaying one of the two points on the lower center of the screen and the other on the upper center of the screen, , Are processed in the same manner.

In order to realize the bird's-eye view display as shown in FIGS. 10 (c) and 16 (c), the coordinate conversion means 62, at step 1031, displays the current position as shown in FIGS. 10 (a) and 16 (a). The angle φ formed by the line perpendicular to the line segment connecting the and the destination and the base of the map mesh is obtained, and step 1032 is performed.
At, the coordinate values of the map data to be drawn are affine-transformed by the angle φ.

Since it is determined in step 1040 that the bird's-eye view is to be displayed, the coordinate conversion means 62 moves to the process of calculating the projection angle θ and the viewpoint position (step 10).
51 and 1052). As described above, the initial value of the projection angle θ is a predetermined value of 30 to 40 °,
It is changed according to the input by the projection angle change key 68.
Also, the initial position of the projection surface is determined so that the difference value obtained by subtracting the position coordinates of the projection surface from the coordinates of the current position becomes a predetermined value as described above, and according to the input by the scale designation key 67. Be changed. Further, the conversion formulas shown in (Equation 2) and (Equation 3) are used to rotate the coordinates,
For the affine transformation, the transformation formula shown in the above (Equation 1) is used. As for the parameters Ty and Tz indicating the position of the projection surface, by substituting an appropriate value in Tx, for example, 0, substituting the position coordinates of the current position and the destination and the displayed position, and solving the simultaneous linear equations. Desired.

Next, the coordinate conversion means 62 executes perspective conversion calculation processing (step 1053). That is, the coordinate conversion means 62 perspectively transforms each coordinate value of the map data using the projection angle θ and the position of the projection surface obtained as described above.

As a result, the graphics processing means 49 draws the obtained map data to display the present location and the destination on the same screen. If these processes are executed every time the current location changes, the current location and the destination are displayed at the same position on the same screen even if the current location changes over time. If it is determined that the perspective conversion process is necessary in the determination in step 1040 during the bird's-eye view display, the screen display is always changed in response to the temporal change of the current location.
Further, in the determination in step 1040, only when the current position has moved by a predetermined distance or more,
If it is determined that the perspective conversion process is necessary, only the mark 105 indicating the current position moves on the same bird's-eye view map until the current position moves for a fixed distance, and the current position moves for a fixed distance to approach the destination. Then, the map display will change to an enlarged one.

By executing the above processing each time the current location changes and fixing the positions of the current location and the destination displayed on the screen, the map can be enlarged and displayed as the destination approaches.

When the distance between the present location and the destination is shortened, the projection angle θ is changed to a smaller value so that the relationship between the present location and the destination can be understood by the bird's eye view display when the distance is far. For ease of use, and if the distance between the current location and the destination is close, it is possible to display the display close to the plan view. Alternatively, conversely, as the distance between the current location and the destination becomes shorter, the projection angle θ is changed to a larger value, making it easier to grasp the overall positional relationship when the distance between the current location and the destination is large. Display the plan view so that
The sense of distance may be easily grasped by displaying such that the viewpoint position gradually rises as the distance between the current position and the destination decreases.

Next, a method of drawing character data in the bird's eye view display will be described. First, details of the perspective transformation calculation (step 1053) of the coordinate transformation means 62 will be described with reference to FIG.

The coordinate conversion means 62 first determines whether the input map data is surface data (step 1100).
When it is determined that the data is surface data, the coordinate conversion unit 62 uses the parameters obtained in the projection angle θ calculation (step 1051) and the viewpoint position calculation (step 1052) to perform perspective conversion of each node coordinate value of the given surface data. (Step 1101). The perspective transformation process (step 1101) for this node is repeated until the process for all input nodes is completed (step 1102).

Next, the coordinate conversion means 62 executes the same process for the line data as for the line data, and perspective-transforms the coordinate values of each node (steps 1103 to 1105).

When the processing for the line data is completed, the coordinate conversion means 62 determines whether the input map data is character data (step 1106). When it is determined that the data is character data, the perspective conversion unit 62 uses the projection angle θ and the viewpoint position coordinate value obtained in steps 1051 and 1052 for the coordinate value of the point where the drawing of the given character string is started. Conversion is performed (step 1107). In addition,
In this embodiment, perspective conversion is not performed on the character image. The node perspective transformation processing in step 1107 is repeated until the processing for all input nodes is completed (step 1108).

When graphics drawing is performed using the obtained perspective conversion result, for example, a bird's-eye view such as the map 103 shown in FIG. 1 is obtained. In this embodiment, step 110
Since the perspective conversion of the character image is not performed in 7,
As shown in the map 103 of FIG. 1, all the characters are drawn in the same size and upright.

Next, the processing of the drawing determination means 63 will be described with reference to FIG. It is means for determining whether or not to draw each data included in the map data.

First, the drawing determination means 63 determines whether the input map data includes surface data (step 1).
200). When it is determined that the surface data is included, the drawing determination unit 63 performs predetermined surface data drawing determination processing (step 1201). The surface data drawing determination process (step 1201) performed here is, for example, a process of determining an attribute predetermined for each surface data and selecting a required predetermined surface data.

When the processing relating to this surface data is completed,
The drawing determination means 63 then determines whether the input map data includes line data such as roads and line backgrounds (step 1202). When it is determined that the line data is included, the drawing determination means 63 performs a predetermined line data drawing determination process (step 1203). The line data drawing determination process (step 1203) performed here is, for example, a process of determining an attribute predetermined for each line data and selecting a required predetermined line data.

When the processing for this line data is also completed,
The drawing determination means 63 then determines whether the input map data includes character data (step 1204).
When it is determined that the character data is included, the drawing determination means 63
First, the rearrangement process is performed so that the coordinate values of the point where the drawing of the character string is started are arranged from the far side of the viewpoint to the vicinity of the viewpoint (step 1205).

Next, the drawing judging means 63 compares the height y of the point where drawing of each rearranged character string is started with the predetermined height h on the display screen (S). Step 1206). In this embodiment, the height h
Is a height of ⅔ from the bottom when the height of the display screen is 1, and is a predetermined constant value. This is because normally when the height from the bottom is ⅔ or more, the depression angle becomes very small and the density of nodes to be drawn becomes very high. However, this reference value (height h) may be set according to the height of the viewpoint or the like.

Further, the distance from the viewpoint may be used as a criterion for drawing a character string, instead of its height. For example, when the distance between the viewpoint and the destination is 1, only the character string whose distance from the viewpoint is 2/3 or less is drawn,
A character string having a distance longer than 2/3 may be deleted from the drawing target.

As a result of the position determination, the drawing judging means 63 makes the character string a drawing object if the height y of the point on the screen where the drawing of the character string is started is lower than the height h, and if it is high, the character string is drawn. Delete the string from the drawing target character string (step 12)
07). In this way, in the present embodiment, the graphics processing unit 49 draws the map data selected by the drawing determination unit 63 to prevent the bird's-eye view display from becoming complicated, and a clear and easy-to-see display is provided. Obtainable.

In the present embodiment, whether or not to draw a character string is determined based only on the displayed height. However, the priority of each character string is set in advance and the displayed height (or The priority range of the character string to be displayed may be determined according to the distance from the viewpoint, and only the character string with the priority included in the range may be drawn. For example,
The upper limit of the priority of the character string to be displayed is constant regardless of the height, and the lower limit of the priority of the character string to be displayed is set to be higher according to the height on the display screen. In the near area, only the character string with high priority is displayed, and in the area near the bottom of the display screen, not only the character string with high priority but also the character string with low priority is displayed. Therefore, when the current position is near the bottom of the display screen, the closer to the current position, the more detailed character information can be obtained, and the farther from the current position, the more important information is displayed. It is highly likely.

If attributes (character font of display characters, meaning contents of character strings, etc.) are set in advance for each character string, this attribute is used instead of the above priority and is set in advance for each area. You may make it display only the character of the specified attribute.

If a character string is defined at a predetermined point as the destination, only the character string may be displayed.

The above steps 1205-1207 are
It can be omitted, but it is preferable to execute it. The effect of these steps will be described with reference to FIGS. 13 and 14. Note that FIG. 13A shows steps 1205 to 1205.
FIG. 11 is a bird's-eye view obtained when drawing is performed without performing the rearrangement process and the drawing character string selection process of 1207. FIG.
(B) and FIG. 14 (a), it executes the reordering process in step 1205, a bird's-eye view obtained when drawn without drawing string selection processing in step 1206 and 1207. FIG. 14B is a bird's-eye view obtained according to the present embodiment, that is, a bird's-eye view obtained when the processing of steps 1205-1207 is executed. Note that FIG.
3 and FIG. 14, illustrations of figures drawn based on surface data and line data are omitted.

When the bird's-eye view display is performed without performing the rearrangement processing in step 1205, each character string is displayed according to the storage order of the character string, regardless of the distance from the viewpoint, as shown in FIG. , A character string far from the viewpoint may be overlaid and displayed on a character string near the viewpoint.

On the other hand, when the character string rearrangement processing in step 1205 is executed, as shown in FIG.
When the character string far from the viewpoint and the character string near the viewpoint overlap, the character string closer to the viewpoint is displayed over the character string farther from the viewpoint. The bird's-eye view displayed in this manner is preferable because the information closer to the current location can be easily read.

If the bird's-eye view is displayed without performing the drawing character string selection processing in steps 1206 and 1207,
As shown in FIG. 14A, the farther from the viewpoint, the smaller the depression angle from the viewpoint, so the compression is reduced, and the amount of data of lines, planes, and characters drawn per unit area increases. Since character data among these data is drawn on top of other data, lines and plane backgrounds are hidden by the drawn character data. In such a bird's-eye view, it is very difficult to read surface information such as roads, rivers, and green areas in the distance from the display screen.

On the other hand, in this embodiment, since the drawing character string selection processing of steps 1206 and 1207 is executed, as shown in FIG. 14B, the height from the bottom of the display screen is h.
Character data in the range up to (character drawing range) is drawn, and other character data is not drawn. Therefore, in the bird's-eye view drawn by the present embodiment, it is possible to easily read the surface information such as roads, rivers, and green areas far from the viewpoint on the display screen.

The bird's-eye view display device and navigation system of this embodiment can display a map represented by a bird's-eye view. Therefore, according to the present embodiment, the user can obtain a map display that is easy to see and in which the positional relationship of the points displayed in the map is easy to recognize. In addition to such effects, the present embodiment is considered to have the effects listed below.

First, in the present embodiment, the plane map display and the bird's eye view display can be arbitrarily switched. Therefore,
In this embodiment, both the plan view and the bird's-eye view can be displayed according to the user's request.

Secondly, in this embodiment, when the bird's-eye view display and the plan map display are switched, the angle formed by the plane projecting the map and the plane containing the map data is gradually increased or decreased in time series. That is, in this embodiment,
When converting between a flat map display and a bird's-eye view display, the viewpoint for obtaining a bird's-eye view moves smoothly. Therefore, in this embodiment, since the transition between the plan view and the bird's-eye view is smoothly performed, it is possible to easily recognize the correlation between the point displayed on the plan map and the point displayed on the bird's-eye map.

Thirdly, in the present embodiment, the viewpoint for obtaining the bird's-eye view can be fixed at a position which is always away from the current position in a certain direction and a certain distance, and the height of the viewpoint can be changed according to the operation input. Can be changed. If the viewpoint is fixed, the bird's-eye view is displayed so that the current position is always fixed at a certain point on the screen, so that the user can easily grasp the current position. Further, according to this embodiment, the viewpoint position can be set to a position desired by the user.

Fourth, in this embodiment, two points (for example,
When the positions of the present location and the destination are specified, the angle between the plane that projects the viewpoint and the map and the plane that contains the map data is determined so that the two points are displayed at the defined positions on the screen. , The bird's-eye view display is executed using the result. Therefore, according to the present embodiment, it is possible to easily determine the positional relationship between the two points. Also, even if the positions of the two points change, they are always displayed on the same screen,
The user can grasp the positional relationship between the two points without performing a complicated operation.

Fifth, the coordinate transformation means of this embodiment does not perform perspective transformation on character images. Therefore, in the present embodiment, all the characters included in the bird's-eye view are displayed upright with the same size, which is easy to read.

Sixth, the drawing determination means of this embodiment determines the character data position in the map data from the viewpoint according to the distance.
Sort character data strings. That is, a character string closer to the position from the viewpoint is treated as having a higher display priority. Therefore, in the present embodiment, the character data in the vicinity of the viewpoint is displayed without being lost because it is covered with another display, and thus it becomes easy to identify the character information close to the viewpoint.

Seventh, the drawing determination means of the present embodiment deletes the character string from the drawing target when the drawing height of the character string on the screen obtained as a result of the perspective transformation of the map is higher than a predetermined value. . Alternatively, the drawing determination means may delete the character string defined at a position more than a predetermined distance from the viewpoint from the drawing target. In this way, a character string is used for an area that is greater than or equal to a predetermined height or a predetermined distance, that is, when the bird's eye view is displayed, the depression angle is small and the amount of data drawn per unit area is very large. By not drawing, the road display, the surface background display, and the like in this area are not covered by the character string display. Therefore, in this embodiment, the bird's-eye view display does not hinder the recognition of the road and the like far from the viewpoint. .

[0135]

The bird's-eye view display device and the navigation system including the device of the present invention can display a map represented by a bird's-eye view. Therefore, according to the present invention, it is possible to obtain a map display that is easy to see and in which the positional relationship of points displayed in the map is easy to recognize.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a bird's-eye view display example of a map drawn according to the present invention.

FIG. 2 is a configuration diagram of a navigation system according to an embodiment.

FIG. 3 is a hardware configuration diagram of an arithmetic processing unit.

FIG. 4 is a functional block diagram of an arithmetic processing unit.

FIG. 5 is a functional block diagram of map drawing means.

FIG. 6 is an explanatory diagram showing perspective transformation of a map.

FIG. 7 is an explanatory diagram showing a coordinate conversion process for displaying a bird's-eye view.

FIG. 8 is a flowchart showing a processing flow of a coordinate conversion unit.

FIG. 9 is an explanatory diagram showing a method of setting a viewpoint and a projection surface for displaying a bird's-eye view.

FIG. 10 is an explanatory diagram showing a method of setting a viewpoint and a projection surface for displaying a bird's-eye view.

FIG. 11 is a flowchart showing the flow of perspective transformation calculation.

FIG. 12 is a flowchart showing a processing flow of a drawing determination unit.

FIG. 13 is an explanatory diagram illustrating an effect of a character string rearrangement process.

FIG. 14 is an explanatory diagram showing an effect of a drawn character string selection process.

FIG. 15 is an explanatory diagram showing a method of setting a viewpoint and a projection surface for displaying a bird's-eye view.

FIG. 16 is an explanatory diagram showing a method of setting a viewpoint and a projection surface for displaying a bird's-eye view.

FIG. 17 is an external perspective view of the navigation system according to the embodiment.

[Explanation of Codes] 1 ... Arithmetic processing unit, 2 ... Display, 3 ... Map storage device, 4 ... Voice input / output device, 5 ... Input device, 6 ... Wheel speed sensor, 7 ... Geomagnetic sensor, 8 ... Gyro, 9 ... GPS receiver, 10 ... Traffic information receiver, 21 ... CPU, 22
... RAM, 23 ... ROM, 24 ... DMA, 25 ... drawing controller, 26 ... VRAM, 27 ... color palette,
28 ... A / D converter, 29 ... SCI, 30 ... I / O device, 31 ... Counter, 41 ... User operation analysis means, 42
... Route calculation means, 43 ... Route guidance means, 44 ... Map drawing means, 45 ... Current position calculation means, 46 ... Map match processing means, 47 ... Data reading processing means, 48 ... Menu drawing means, 49 ... Graphics processing means , 61 ... Initial data clipping means, 62 ... Coordinate conversion means, 63 ... Drawing determination means, 64 ... Data clipping means, 65 ... Drawing command issuing means, 66 ... Scroll key, 67 ... Scale change key, 68 ... Projection angle change key , 69 ... Casing, 70 ... Touch sensor.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshinori Endo             7-1-1, Omika-cho, Hitachi-shi, Ibaraki Prefecture             Inside the Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Toshio Fujiwara             7-1-1, Omika-cho, Hitachi-shi, Ibaraki Prefecture             Inside the Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Hiroyuki Satake             7-1-1, Omika-cho, Hitachi-shi, Ibaraki Prefecture             Inside the Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Hiroshi Masashima             7-1-1, Omika-cho, Hitachi-shi, Ibaraki Prefecture             Inside the Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Norimasa Kishi             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation (72) Inventor Masayuki Watanabe             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation (72) Inventor Motomitsu Hirano             2499-1 Hironodai, Zama City, Kanagawa Prefecture             In ceremony company Xanavi Informatics F term (reference) 2C032 HB22 HB25 HB31 HC08 HC14                       HC16 HC22 HC23 HC24 HC25                       HC31 HD03 HD07 HD16 HD30                 2F029 AA02 AB01 AB07 AC02 AC04                       AC14 AC18 AD08                 5B050 BA07 BA17 CA07 EA12 EA27                       FA02                 5H180 AA01 BB12 BB13 EE18 FF04                       FF05 FF12 FF13 FF23 FF25                       FF27 FF33

Claims (37)

[Claims] 1. A map drawing data is created by using an image display device, a map storage means for holding map data for displaying a map, and map data read from the map storage means. In a map display device including a map drawing means for displaying an image of a map on the image display device, the map drawing means includes coordinate conversion means for converting coordinate data included in the map data, and the coordinate conversion means The means is, from the defined position as the viewpoint, to the defined projection plane,
Perspective transformation of the coordinate data included in the above map data,
A map display device comprising a perspective conversion means for creating drawing data of a bird's-eye view. 2. The apparatus according to claim 1, further comprising an input device, wherein the coordinate conversion means includes means for accepting an input of the position of the viewpoint via the input device, and the coordinate conversion means is predetermined in the map data. And means for determining the projection plane so that the drawing positions of the two points after the perspective transformation become predetermined positions based on the coordinates of the two points and the input viewpoint position. A map display device characterized by the above. 3. The input device according to claim 1, further comprising an input device, wherein the coordinate conversion means receives a scale factor input through the input device, and two predetermined points included in the map data. Based on the coordinates of and the input scale ratio, the drawing positions of the two points after the perspective transformation become predetermined positions, and the drawing scale ratio becomes the input scale ratio. And a means for determining the position of the viewpoint and the projection plane. 4. The projection device according to claim 1, further comprising an input device, wherein the coordinate transformation means forms an angle between the plane defined by the map data and the projection plane via the input device. A map display device comprising: means for accepting the input of, and means for determining the projection plane based on the input projection angle and the determined viewpoint position. 5. A means for creating drawing data of a plan view without performing the perspective conversion, and a drawing determining means for deciding which drawing data of the bird's-eye view or the plan view is created, according to claim 1. A map display device, further comprising: 6. The drawing selection according to claim 5, further comprising an input device, wherein the coordinate conversion means receives an instruction of which drawing data of the bird's-eye view or the plan view is to be created via the input device. The map display device, further comprising a receiving unit, wherein the drawing determining unit determines the drawing data to be created according to the instruction received by the drawing selection receiving unit. 7. The projection angle for obtaining the bird's-eye view according to claim 5, wherein the map drawing means changes the drawing data to be created from one of the bird's-eye view and the plan view to the other. Is set as the first projection angle, the coordinate conversion means is caused to create one or more second bird's-eye view drawing data perspective-transformed using the second projection angle smaller than the first projection angle, A map image is displayed on the image display device by using the drawing data of the second bird's-eye view between the display of the bird's-eye view obtained by the perspective transformation with the first projection angle and the display of the plan view. A map display device further comprising projection angle changing means. 8. The projection angle changing means according to claim 7, wherein the projection angle changing means uses two or more second projection angles different from each other to create drawing data of two or more second bird's-eye views. If the drawing data to be created is changed from the bird's-eye view to the plan, the two or more second bird's-eye views are displayed in descending order of the projection angle, and the drawing data to be created is changed to the plane. A map display device characterized in that, if the drawing is changed to the bird's-eye view, the two or more second bird's-eye views are displayed in ascending order of projection angle. 9. The map drawing means according to claim 6, further comprising means for accepting designation of an arbitrary point included in the map data via the input device, wherein the drawing determination means is the arbitrary device. When receiving the designation of the point, the map display device is characterized in that the drawing data to be created is the drawing data of the plan view. 10. The coordinate data according to claim 1, wherein the map data includes, as character string data, vector data for recognizing a position of the character string and image data for recognizing an image of the character string, The map display device, wherein the conversion means does not perform the perspective conversion for the image data of the map data. 11. The map drawing means according to claim 1, wherein the map drawing means judges whether or not the data of one or more nodes included in the drawing data is to be drawn, and the data of the nodes not to be drawn are drawn. The map drawing means further comprises drawing determination means for deleting from the data, and the map drawing means displays the map image on the image display device using the drawing data processed by the drawing determination means. Map display device. 12. The determination according to claim 11, wherein if the data of the node is character string data, the height from the bottom of the display position of the character string on the display screen after the perspective conversion is calculated in advance. A map display device characterized in that it is carried out depending on whether or not it is below a predetermined reference value. 13. The map display device according to claim 12, wherein the reference value is 2/3 from the bottom side when the height of the display screen is 1. 14. The determination according to claim 11, wherein when the data of the node is character string data, the distance between the defined position of the character string in the map data and the viewpoint is determined in advance. A map display device characterized in that it is carried out depending on whether or not it is equal to or less than a predetermined reference value. 15. The determination according to claim 11, wherein if the data of the node is character string data, a predetermined position of the character string in the map data and a predetermined position included in the map data are determined. The distance to the point is
A map display device characterized in that it is carried out depending on whether or not it is below a predetermined reference value. 16. The attribute according to claim 11, wherein at least a part of each of the nodes has an attribute defined in advance, and the drawing determination means conforms to the attribute predetermined for each display area of the display screen. The map display device is characterized in that the data of the node is a drawing target, and the data of the node having an incompatible attribute is not a drawing target. 17. The map display device according to claim 1, wherein the coordinate conversion means changes the projection angle according to a distance between two predetermined points included in the map data. . 18. The coordinate conversion means according to claim 17, wherein the shorter the distance between the two points is,
A map display device characterized by reducing a projection angle. 19. The map data according to claim 1, wherein the map data includes data of a character string, and the map drawing means determines a priority of displaying the character string, and one or more of the map display means. A map display device comprising: a character string rearranging means for displaying the character string having the highest priority among the overlapping character strings when the display positions of the character strings overlap. 20. The map display device according to claim 19, wherein the priority order is determined according to the height of the display position of the character string on the display screen from the bottom side of the display screen. 21. The map display device according to claim 20, wherein the priority is set higher as the display position of the character string on the display screen is lower from the bottom of the display screen. 22. The priority order according to claim 19, wherein the priority is determined according to a distance between a predetermined point included in the map data and a point defined by the character string. And a map display device. 23. The map display device according to claim 22, wherein the priority is set higher as the distance between the predetermined point and the point where the character string is defined is shorter. 24. An image display device, map storage means for holding map data for displaying a map, map data read from the map storage means is used to create map drawing data, and the drawing data is stored. In a map display device comprising a map drawing means for displaying an image of a map on the image display device, the map data includes data of a character string, and the map drawing means has a display priority of the character string. When the display positions of the one or more character strings overlap in the display of the map, the character string rearrangement for displaying the character string having the highest priority among the overlapping character strings. A map display device comprising means. 25. An image display device, map storage means for holding map data for displaying a map, map drawing data created from the map data read from the map storage means, and map drawing data is created. In a map display device comprising a map drawing means for displaying an image of a map on the image display device using the current position recognition means for recognizing its own position, the map drawing means stores the coordinate data included in the map data. Coordinate conversion means for converting is provided, and the coordinate conversion means has a predetermined position as a viewpoint, on a predetermined projection plane,
Perspective transformation of the coordinate data included in the above map data,
A navigation system comprising perspective conversion means for creating drawing data of a bird's-eye view. 26. An input device according to claim 25, further comprising an input device, wherein the coordinate conversion means includes means for accepting an input of the position of the viewpoint through the input device, and a predetermined value included in the map data. And means for determining the projection plane so that the drawing positions of the two points after the perspective transformation become predetermined positions based on the coordinates of the two points and the input viewpoint position. A navigation system characterized by that. 27. The navigation system according to claim 26, wherein one of the two points is the own position recognized by the current position recognition means. 28. The input device according to claim 25, further comprising an input device, wherein the coordinate conversion means receives a scale factor input through the input device, and two predetermined points included in the map data. Based on the coordinates of and the input scale ratio, the drawing positions of the two points after the perspective transformation become predetermined positions, and the drawing scale ratio becomes the input scale ratio. And a means for determining the position of the viewpoint and the projection plane. 29. The navigation system according to claim 28, wherein one of the two points is the own position recognized by the current position recognition means. 30. The input device according to claim 25, further comprising an input device, wherein the coordinate conversion means receives the designated position via the input device and the own position recognized by the current position recognition means. A navigation system, characterized in that the projection angle is changed in accordance with the distance to. 31. The map data according to claim 25, wherein the map data includes character string data, and the map drawing means defines the character string data included in the drawing data in the map data. Position, and whether or not to be a drawing target according to the distance between the point on the map data corresponding to the own position recognized by the current position recognition means, the data of the node that is not the drawing target,
The map drawing means displays a map image on the image display device using the drawing data after being processed by the drawing judging means. Navigation system. 32. The map data according to claim 25, wherein the map data includes character string data, and the map drawing means determines one or more of the display priority of the character string and one or more of the map display means. When the display positions of the character strings overlap, a character string rearranging unit that displays the character string having the highest priority among the overlapping character strings is provided, and the priority is the current position recognition. A navigation system characterized by being determined according to a distance between a point on the map data corresponding to the own position recognized by the means and a point defined by the character string. 33. The coordinate conversion means according to claim 25, wherein when the height component of the coordinates of the display position of the own position recognized by the current position recognition means sets the height of the display screen to 1, Viewpoint or projection angle so that it becomes 1/3 or less,
A navigation system comprising means for defining a projection plane. 34. A bird's-eye view creating method for creating drawing data of a map represented by a bird's-eye view using map data, wherein a predetermined position is set as a viewpoint and a predetermined projection plane is set.
Perspective transformation of the coordinate data included in the above map data,
A bird's-eye view creation method characterized by creating drawing data of a bird's-eye view. 35. The method according to claim 34, wherein the step of receiving an input of the position of the viewpoint, the coordinates of two predetermined points included in the map data, and the input viewpoint position are used. And a step of deciding the projection plane so that the drawing positions of the two points after the perspective conversion become predetermined positions. 36. The step of receiving an input of a scale factor, the coordinate of two predetermined points included in the map data, and the perspective transform based on the input scale factor according to claim 34. And a step of determining the position of the viewpoint and the projection plane so that the subsequent drawing positions of the two points become predetermined positions and the drawing scale ratio becomes the input scale ratio. A characteristic bird's-eye view creation method. 37. In claim 34, a step of receiving an input of a projection angle, which is an angle formed by the plane defined by the map data and the projection plane, the input projection angle, and the determined projection angle. And a step of determining the projection plane based on a viewpoint position.