JP6016684B2 - 3D map display system - Google Patents

Description

  The present invention relates to a three-dimensional map display system that displays a three-dimensional map in a bird's eye view.

An electronic map used for a navigation device, a computer screen, or the like may use a three-dimensional map that three-dimensionally represents a feature such as a building. A three-dimensional map is usually displayed by drawing a three-dimensional model three-dimensionally by perspective projection or the like. A three-dimensional map displayed in a bird's eye view by drawing in a state of looking down from an upper viewpoint position is highly useful because it can display a wide range with a sense of perspective.
In a three-dimensional map, it is desirable to display a linear object such as a road or a railroad using a polygon model in order to give a sense of perspective and realize a realistic expression.

JP 2003-337033 A

However, in the bird's-eye view display, there is a problem that in a distant area far from the viewpoint position, the display is crushed and becomes difficult to visually recognize. In particular, in the case of a linear object such as a road or a railroad, it is drawn with a thin line at a distance, and it may be almost impossible to visually recognize it.
As a method for solving such a problem, when displaying a bird's-eye view, Patent Literature 1 displays a corrected road with a wide width because the line width of the road drawn to the left and right is very narrow and cannot be seen at a distance. The technique which improves visibility by this is disclosed. However, since it is not possible to correct the shape of the polygon model with a light processing load, the method of Patent Document 1 draws a distant linear object that is not very important for display. In addition, another problem of unnecessarily applying a processing load is caused.
The present invention has been made in view of the above problems, and an object of the present invention is to improve the visibility of a linear object in a three-dimensional map display in a bird's eye view while suppressing an increase in processing load.

The present invention
A 3D map display system for displaying a 3D map,
A map database that stores line data representing linear objects;
For the linear object, separately from the line data, a line drawing data setting unit that prepares polygon data representing the linear object as drawing data;
A display control unit that refers to the map database and displays a bird's eye view of a three-dimensional map viewed from the designated viewpoint position and line-of-sight direction;
The display control unit can be configured as a three-dimensional map display system that uses both line data drawing and polygon data drawing for the linear object.
The line object refers to an object whose shape can be represented by line data, that is, broken line data, and includes, for example, a road, a railroad, a route guidance display, and a river.

  According to the present invention, by combining drawing with line data and drawing with polygon data, it is possible to display a three-dimensional map taking advantage of both advantages. Since the line data represents the shape of the linear object with a polygonal line, the expression of perspective is poor, but on the other hand, there is an advantage that the line data is drawn with a constant thickness even at a point far from the viewpoint. Polygon data, on the other hand, has the advantage of giving perspective to a linear object with a width corresponding to the distance from the viewpoint. Has the disadvantage of becoming too thin and difficult to see. In a three-dimensional map, a map database usually has a single polygon model for representing features. In this method, drawing is performed using either line data or polygon data. Will do. On the other hand, in the present invention, since drawing is performed using two drawing data, line data and polygon data, for a linear object, it is possible to draw using the advantages of both.

A method for realizing drawing using both of them is as follows.
In the present invention, line data is stored in the map database for linear objects. Then, the line drawing data setting unit prepares polygon data representing the linear object as drawing data separately from the line data for the linear object. In other words, in general, for a single linear object, it is sufficient to draw using line data stored in the map database. Is also prepared.
“Preparation” means that when polygon data of a linear object is also stored in the map database, the polygon data is specified as a drawing target, and when polygon data is not stored, This means that polygon data is generated and used as a drawing target. However, these processes do not necessarily mean that the same identification information is attached to the line data and the polygon data. It is only necessary to prepare two types of drawing data for one common linear object.

  In the present invention, in addition to the above-described advantages, line data is stored in the map database in order to represent a linear object, so that there is an effect that the data capacity of the map database can be suppressed.

In the present invention,
The line drawing data setting unit may generate the polygon data based on the line data.
By doing so, there is no need to store line data and polygon data in the map database, and there is an advantage that the data capacity can be suppressed.
Polygons can be generated relatively easily without giving an excessive increase in calculation load by giving width to line data. The width given to the line data can be set based on the attribute information given to the line data. For example, when the linear object is a road, the width to be given to the line data can be specified by giving the number of lanes of the road, the lane width, etc. as attribute information.

In the present invention, the display control unit may perform both drawing with the line data and drawing with the polygon data over the entire linear object.
By doing this, in the foreground area relatively close to the viewpoint, the drawing by the polygon data drawn with a width is mainly visually recognized, and in the far area where the polygon is drawn thinly, the line data drawn with a constant thickness Drawing by is mainly visually recognized. Accordingly, by drawing both over the whole, it is possible to take advantage of the drawing of polygon data and line data naturally.

As another aspect,
The display control unit draws a range from the viewpoint position to a first distance with respect to the linear object by using only the polygon data, and a range having a distance from the viewpoint of a second distance or more by using only the line data. It is good also as what draws.
By doing this, it is possible to draw the near area with polygon data and the far area with line data. In order to represent a linear object, since a space | gap must not arise between polygon data and line data, the relationship that 1st distance is more than 2nd distance is calculated | required.
When “first distance = second distance”, the polygon data and the line data are switched and drawn with the first distance as a boundary.
When “first distance> second distance”, it is drawn as follows.
Range from the viewpoint position to the second distance: drawing with only polygon data;
Range from the second distance to the first distance: drawing with both polygon data and line data;
Range farther than the first distance: drawing with line data only;
In the above-described aspect, there may be a part using both polygon data and line data in a part of the range.

In the present invention, it is not always necessary to include all of the various features described above, and some of the features may be omitted or combined as appropriate.
In addition, the present invention may be configured as a 3D map display method for displaying a 3D map by a computer, or may be configured as a computer program for causing a computer to execute such display. Moreover, you may comprise as a computer-readable recording medium which recorded such a computer program.

It is explanatory drawing which shows the structure of a three-dimensional map display system. It is explanatory drawing which shows the structure of a three-dimensional map database. It is a flowchart of a route guidance process. It is a flowchart of a map display process. It is explanatory drawing which shows the example of the route guidance display which used the polygon and the line together. It is explanatory drawing which shows the example of the route guidance display by a line. It is explanatory drawing which shows the example of the route guidance display by a polygon. It is explanatory drawing which shows the example of the road display in 2nd Example. It is a flowchart of the map display process in 2nd Example.

A. System configuration:
FIG. 1 is an explanatory diagram showing a configuration of a three-dimensional map display system. The three-dimensional map display system of the present embodiment is a system that performs route search and performs route guidance while displaying a three-dimensional map. The 3D map display system may be configured as a system that does not involve route search and route guidance functions, and simply displays a 3D map in accordance with an instruction from the user.
The three-dimensional map display system of the embodiment is configured by connecting a server 200 and a terminal 300 via a network NE2. As the terminal 300, a smartphone is used, but various devices capable of displaying a map, such as a mobile phone, a portable information terminal, and a personal computer, can be used.

The server 200 and the terminal 300 are provided with various functional blocks illustrated. In the present embodiment, these functional blocks are configured by software by installing computer programs for realizing the respective functions in the server 200 and the terminal 300, but a part or all of the functional blocks are configured by hardware. May be.
In the present embodiment, the configuration including the server 200 and the terminal 300 is adopted. However, the 3D map display system may be configured as a stand-alone device, or may be configured as a distributed system including more servers. Also good.

(1) About Server 200 The map database 210 stores a three-dimensional map database 211 and network data 213. The 3D map database 211 stores polygon data, line data, and character data representing the 3D shape of the feature. The network data 213 is route search data in which roads are represented by links and nodes.
The contents of the 3D map database 211 will be described. In this embodiment, the features are handled by dividing them into linear objects and other general features. A linear object is a general term for linear features such as roads, and refers to an object whose shape can be represented by line data, that is, broken line data. The linear objects include, for example, roads, tracks, route guidance displays, rivers, and the like. General features other than linear objects include buildings and the like. In the three-dimensional map database 211, polygon data representing a three-dimensional shape is prepared for general features such as buildings. Line data is prepared for linear objects. However, as described later, polygon data may be prepared for a linear object.
The database management unit 202 manages data input / output of the map database 210.
The route search unit 203 uses the network data 213 to search for a route from the departure point specified by the user of the terminal 300 to the destination. The route search can be performed by a known method such as the Dijkstra method.
The transmission / reception unit 201 transmits / receives various data and commands to / from the terminal 300 via the network NE2.

(2) About the terminal 300 The main control unit 304 performs integrated control of the operation of each functional block provided in the terminal 300.
The transmission / reception unit 301 transmits / receives data and commands to / from the server 200 via the network NE2.
The command input unit 302 inputs an instruction regarding route guidance from the user. Examples of the instructions include a route guidance starting point, destination designation, and display scale designation during map display.
The position / traffic information acquisition unit 303 acquires the current position of the terminal 300 from a sensor such as a GPS (Global Positioning System), or acquires information on traffic congestion and traffic control via the network NE2.
The map information storage unit 305 temporarily stores the three-dimensional map database 211 acquired from the server 200 when displaying a map. In the present embodiment, the terminal 300 does not store all map data in advance, but appropriately acquires map data required according to the map display range from the server 200. The map information storage unit 305 stores the map data acquired in this way. In addition, a route search result is also stored.
The display control unit 306 performs map display on the display 300 d of the terminal 300 using the map data stored in the map information storage unit 305.
The line drawing data setting unit 307 has a function of preparing data necessary for drawing a linear object. In this embodiment, as will be described later, a part of a linear object is drawn using both line data and polygon data. When both pieces of data are stored in the map information storage unit 305, it is necessary to perform processing for rendering both. When polygon data does not exist, it is necessary to generate polygon data from line data. The line drawing data setting unit 307 executes these processes.
In the present embodiment, a linear object that uses both line data and polygon data is referred to as a superimposed drawing object. All of the linear objects may be superposed drawing objects, or a part thereof may be treated as a superposed drawing object. For example, a specific type of linear objects may be used as a superimposed drawing object, or by setting a flag, it may be possible to individually specify whether or not to use a superimposed drawing object.

B. Map database:
FIG. 2 is an explanatory diagram showing the structure of a three-dimensional map database. The three-dimensional map database 210 is prepared hierarchically at a plurality of levels with different display scales. The upper layer level is low-detail map data representing a wide range, and the lower layer level is map data representing a slightly narrow range in detail. In addition to the two levels of the upper layer and the lower layer, more levels may be prepared for the level.

  In the lower layer, polygon data representing a three-dimensional shape of a feature such as a building is stored as illustrated. The road is also prepared with polygon data. In the figure, the content of polygon data is shown by taking a road as an example. The polygon data stores unique identification information ID, three-dimensional coordinates such as vertices PP1 and PP2 representing the shape of the polygon, and attributes. The attributes include, for example, information such as road name, road type, road width, or number of lanes. Polygon data is also prepared in a similar format for features such as buildings.

In the upper layer, in order to display a wide range, the road is prepared with line data instead of polygons. The contents of the line data are shown in the figure. The line data stores unique identification information ID, three-dimensional coordinates of vertices PL1 and PL2 representing the shape of the line, and attributes. The content of the attribute is the same as that of the lower layer.
In this embodiment, the data for the same road can be specified by associating the identification information ID of the polygon data and the line data. The same identification information ID may be used for both the polygon data and the line data, or data for associating both may be prepared separately.
Some linear objects, such as the road shown in FIG. 2, have polygon data and line data prepared at different levels. Not all of the linear data and line data are prepared for all linear objects, but some of them have only line data. For example, only route data is prepared for a route guidance display that appears at the time of route guidance, that is, a line or arrow indicating the route.
However, the data structure in the present embodiment is merely an example, and a configuration in which polygon data and line data at different levels are not associated may be employed.

C. Route guidance process:
FIG. 3 is a flowchart of route guidance processing. The route guidance process is a process for searching for a route from the departure point designated by the user to the destination and performing guidance. This is a process mainly performed by the route search unit 203 of the server 200, the display control unit 306 of the terminal 300, and the like, and is a process performed by the CPU of the server 200 and the terminal 300 in terms of hardware.
When the process is started, the terminal 300 inputs the designation of the departure point and the destination from the user (step S10). The current position may be used as the departure place.
The server 200 receives the information of the departure place and the destination from the terminal 300, and performs a route search with reference to the network data 213 (step S11). For the route search, a known method such as Dijkstra method can be used.
Then, route guidance data is created based on the route search result (step S12). The route guidance data is data for drawing a route guidance line or arrow. The route guidance data may be drawing line data using the network data 213, or road line data corresponding to the searched route may be used. In this embodiment, in any case, the route guidance data is prepared in the form of line data. The route guidance data is transmitted to the terminal 300 as a result of the route search.

Next, the terminal 300 performs processing for guiding a route while displaying a three-dimensional map according to the current position of the user.
First, the terminal 300 detects the current position of the user (step S13). The current position can be detected using a sensor such as GPS.
And the terminal 300 displays a three-dimensional map by map display processing (step S14). Details of the processing will be described later.
The terminal 300 repeats the above processing until it reaches the destination (step S15).

FIG. 4 is a flowchart of the map display process. This process corresponds to step S14 of the route guidance process (FIG. 3), and is a process mainly executed by the display control unit 306 of the terminal 300.
When the process is started, the terminal 300 inputs a viewpoint, a line-of-sight direction, and a display scale (Step S20). The viewpoint may be determined based on the current position. The line-of-sight direction may be determined based on the current position and the route to be traveled.
Then, map data and route guidance data in a range to be displayed as a three-dimensional map are read (step S21). In this embodiment, in order to display a three-dimensional map, the terminal 300 first reads data stored in the map information storage unit 305, and when map data is insufficient to display a map. The deficiency is acquired from the server 200.
When the map data is read, the terminal 300 extracts a superimposed drawing object (step S22). As described above, a superimposed drawing object refers to a linear object that is drawn by using polygon data and line data together.

The terminal 300 prepares data for using both the polygon data and the line data as described below for the superimposed drawing object.
First, the terminal 300 reads polygon data or line data of a superimposed drawing object from map data at another level (step S23). As described with reference to FIG. 2, depending on the type of linear object such as a road, line data may be stored in the upper layer and polygon data may be stored in the lower layer. Therefore, the terminal 300 searches for the data prepared in the different hierarchies as described above for the superimposed drawing object, and if these exist, reads them and uses both polygon data and line data as drawing data. Prepare. In this embodiment, line data is always stored for a linear object, but polygon data may not exist even if another hierarchy is searched. For such a linear object, polygon data cannot be prepared in step S23.

Next, the terminal 300 generates a polygon for a superimposed drawing object that does not have polygon data (step S24).
The state of processing was illustrated in the figure. Polygon generation is performed by giving a width to the line data and generating a rectangular polygon. When a rectangular polygon is generated by widening for each vertex in this way, if the line is a broken line, there may be overlap between polygons at the vertex, so for such places, the deletion of duplicate polygons, Generate polygons to fill gaps.
Through the above processing, both polygon data and line data are prepared for the superimposed drawing object.

  In this embodiment, two methods of reading from the map database (step S23) and generating polygon data (step S24) are used in combination, but only one of them may be used. For example, for a linear object, only line data, not polygon data, is prepared in the map database, and step S23 is omitted, and a method of generating polygon data from line data (step S24) is performed. Good.

  When the above processing is completed, the terminal 300 draws a three-dimensional map by perspective projection from the designated viewpoint and line-of-sight direction (step S25). At this time, with respect to the superimposed drawing object, the line and the polygon are drawn so as to overlap in the entire area.

FIG. 5 is an explanatory diagram showing an example of route guidance display using both polygons and lines. On the road, a route guidance line is drawn by superimposing the polygon PP and the line LL, which corresponds to an output example in this embodiment. In order to make it easier to grasp the effect of the display of this embodiment, linear objects other than the route guidance display such as roads are drawn using only polygons as usual.
In the region A that is relatively close to the viewpoint, the polygon PP is mainly visually recognized because the width of the polygon PP exceeds the line LL. Since the width of the polygon PP becomes narrower as it goes farther from the viewpoint, in the area A, it is possible to realize a display with a sense of perspective as a route guidance display.
In the region B far from the viewpoint, the width of the polygon PP becomes very thin, so that the line LL is mainly visually recognized. Accordingly, it is possible to display the route guidance display in a manner that can be easily visually recognized even at a distance from the viewpoint.

As an object to be compared with the output example of this embodiment, a display example using only lines and a display example using only polygons are shown.
FIG. 6 is an explanatory diagram illustrating an example of route guidance display using lines. In both the region A near the viewpoint and the region B far away, the route guidance display is displayed with a constant line width by the line LL. In the case of such a display, there is an advantage that the route guidance display can be clearly seen in the distant region B, but in the region A in the foreground, the display lacks perspective, and the reality and the geography, the route, etc. are intuitively improved. The display is detrimental to the advantage of being a three-dimensional map.
FIG. 7 is an explanatory diagram illustrating an example of a route guidance display using polygons. In both the region A close to the viewpoint and the region B far away, the route guidance display is displayed by the polygon PP. In the case of such display, in the area A in the foreground, there is an advantage that a sense of perspective is given and a display with reality can be realized. However, in the distant region B, the polygon PP is drawn very thin, so that it can hardly be visually recognized.

As described above, according to the three-dimensional map display system of the first embodiment, by using a polygon and a line together for a linear object, in a region close to the viewpoint, a sense of perspective is given and a distance from the viewpoint is obtained. It is possible to realize a display that is clearly visible even in the area.
In the first embodiment, instead of switching between drawing with a polygon and drawing with a line, both are used together over the entire region, so the switching point between the polygon and the line is calculated for each linear object. There is an advantage that it is possible to realize drawing in which both are superimposed without applying a load such as.

Next, a three-dimensional map display system as Example 2 will be described. In the second embodiment, a superimposed drawing object is drawn by switching between a polygon and a line. In this sense, in the second embodiment, the superimposed drawing object is referred to as a switching object.
Since the system configuration (see FIG. 1), data structure (see FIG. 2), route guidance process (see FIG. 3), and the like are the same as those in the first embodiment, the following description will be limited to the map display process.

FIG. 8 is an explanatory diagram showing an example of road display in the second embodiment. As shown in FIG. 8A, in the second embodiment, the range from the viewpoint position to the predetermined distance D is set as the polygon display area, and the area farther than that is set as the line display area. In the polygon display area, the switching object is drawn using polygon data. In the line display area, the switching object is drawn by switching to the line data.
FIG. 8B shows a drawing example of the switching object. In the polygon display area close to the viewpoint position, the polygon P is drawn. In the far line display area, the line L is drawn with a constant line width.
The distance D between the polygon display area and the line display area (hereinafter referred to as “switching distance D”) can be arbitrarily set. For example, the distance between the polygon width and the line width is approximately the same. be able to. However, since the distance depends on the width of the polygon and the width of the line, strictly speaking, the distance differs for each linear object. Therefore, in the second embodiment, for each linear object, the distance at which the width of the polygon and the width of the line are approximately the same may be calculated, and the drawing with the polygon and the drawing with the line may be switched. Further, the switching distance D may be determined as a representative of linear objects having high importance within the display range, and this may be applied to all switching objects. Furthermore, a switching distance D may be set in advance, and this may be applied to all switching objects.

FIG. 9 is a flowchart of the map display process in the second embodiment.
The terminal 300 inputs the viewpoint, line-of-sight direction, and display scale (step S30), and reads map data and route guidance data (step S31). These processes are the same as those in the first embodiment (see FIG. 4).
Next, the terminal 300 extracts a switching object (step S32), and calculates a switching point between a line and a polygon for the switching object (step S33). As shown in the figure, the point of the switching distance D from the viewpoint position is the switching point. The portion L1 closer to the viewpoint position than the switching point is drawn with a polygon, and the far portion L2 is drawn with a line.

  Next, the terminal 300 generates polygon data for drawing in the polygon display area (step S34). The line data is read for the switching object, and the polygon may be generated by giving a width to the line data of the portion L1 closer to the viewpoint position than the switching point as in the first embodiment (see step S24 in FIG. 4). . When polygon data is prepared at another level, polygon data at a location corresponding to the portion L1 may be read and used. However, even when polygon data at other levels is used, it is necessary to perform processing for cutting out only the portion corresponding to the portion L1.

  The terminal 300 performs map drawing processing by perspective projection based on the viewpoint position and the line-of-sight direction using the map data set as described above (step S35). At this time, the polygon display area is drawn using the polygon data of the switching object, and the line display area is drawn using the line data of the switching object.

Even in the 3D map display system of the second embodiment described above, the switching object can be drawn using both of them, such as drawing with a polygon in an area close to the viewpoint and drawing with a line in a distant area. Similar to Example 1, it is possible to realize a three-dimensional map display utilizing each advantage.
Further, although the load for calculating the switching point increases in the second embodiment, there is an advantage that it is not necessary to perform useless drawing such as drawing a polygon that is no longer visible from the viewpoint as in the first embodiment.

The embodiment of the present invention has been described above.
The various feature points described in the first and second embodiments are not necessarily all provided, and may be applied by omitting some or combining them as appropriate.
In addition to the above-described embodiments, the present invention can take various modifications. For example, a part processed by software in the embodiment can be replaced with hardware, and vice versa.

  INDUSTRIAL APPLICABILITY The present invention can be used to improve the reality and visibility as a three-dimensional map in displaying a linear object.

DESCRIPTION OF SYMBOLS 200 ... Server 201 ... Transmission / reception part 202 ... Database management part 203 ... Route search part 210 ... Map database 211 ... Three-dimensional map database 213 ... Network data 300 ... Terminal 301 ... Transmission / reception part 302 ... Command input part 303 ... Acquisition of position and traffic information Reference numeral 304: Main control part 305: Map information storage part 306: Display control part 307: Line drawing data setting part

Claims (5)

A 3D map display system for displaying a 3D map,
A map database that stores line data representing linear objects;
For the linear object, separately from the line data, a line drawing data setting unit that prepares polygon data representing the linear object as drawing data;
A display control unit that refers to the map database and displays a bird's eye view of a three-dimensional map viewed from the designated viewpoint position and line-of-sight direction;
The display control unit is a three-dimensional map display system that performs drawing by the line data and drawing by the polygon data over the entire linear object . The three-dimensional map display system according to claim 1,
The line drawing data setting unit is a three-dimensional map display system that generates the polygon data based on the line data. The three-dimensional display system according to claim 1 or 2,
The three-dimensional map display system in which drawing by the line data by the display control unit is performed with a constant thickness for each linear object regardless of the distance from the viewpoint . A 3D map display method for displaying a 3D map by a computer,
As the steps executed by the computer,
Reading the line data from a map database storing line data representing a linear object;
For the linear object, separately from the line data, preparing polygon data representing the linear object as drawing data;
With reference to the map database, a display control step of displaying a three-dimensional map in a bird's eye view as seen from the designated viewpoint position and line-of-sight direction,
The display control step is a three-dimensional map display method in which drawing with the line data and drawing with the polygon data are overlapped over the entire linear object . A computer program for displaying a three-dimensional map by a computer,
A function of reading the line data from a map database storing line data representing a linear object;
For the linear object, separately from the line data, a function of preparing polygon data representing the linear object as drawing data;
With reference to the map database, the computer realizes a display control function for displaying a three-dimensional map in a bird's eye view as seen from the designated viewpoint position and line-of-sight direction,
The display control function is a computer program which is a function for performing drawing by the line data and drawing by the polygon data over the entire linear object .