JP2015114953A - Three-dimensional map display system and composite texture generation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the load required for texture processing when displaying three-dimensional maps.SOLUTION: Texture for a three-dimensional model is applied to each surface of the three-dimensional model and a projected image obtained by parallel projection is saved as a composite texture. When displaying three-dimensional maps, a three-dimensional model is arranged in a virtual three-dimensional space, the three-dimensional model is then projected in a parallel projection direction PRJ1 and the opposite direction thereto PRJ2, and the composite texture is applied to the surface of the three-dimensional model. Perspective projection, etc., are performed on this three-dimensional model and a three-dimensional map is displayed. As a result, an exterior displayed using a plurality of texture layers can be displayed using one composite texture, and the resolution of the texture itself can be reduced in the composite texture generation process, therefore the texture processing load during display of three-dimensional maps can be reduced.

Description

  The present invention relates to a three-dimensional map display system that displays a three-dimensional map that represents a feature three-dimensionally, and a synthetic texture generation device that generates a synthetic texture used for three-dimensional map display.

In a three-dimensional map that represents three-dimensional features such as buildings and roads on a navigation device or computer screen, a three-dimensional model representing the three-dimensional shape of the feature is projected by a method such as perspective projection. To be displayed. Since a high calculation load is applied to this projection, reducing the calculation load is one of the problems in the three-dimensional map display.
On the other hand, the three-dimensional map has an advantage in that the reality is high and it is easy to grasp the geography intuitively. In order to improve the reality, in the 3D map, a texture representing the appearance of the feature is pasted on the surface of the 3D model. When a texture is affixed, the calculation load of the projection process is further increased, and this reduction in load becomes a further problem.
As a method for solving such a problem, Patent Document 1 provides a texture having a high accuracy for expressing an appearance and a texture having a low accuracy, and uses both depending on the load of the CPU when performing projection processing. A technique for reducing the load is disclosed.

JP 2006-268550 A

When displaying a three-dimensional map over a wide area, the number of three-dimensional models increases and the calculation load increases. In recent years, there has been an increasing demand for displaying a three-dimensional map in a mobile terminal or the like having a relatively low processing capability such as a smartphone, and further reduction in calculation load during map display is desired. In order to reduce the calculation load, a method of simplifying a three-dimensional model or texture is conceivable. However, such a method causes another problem that the reality of the three-dimensional map is reduced.
The present invention has been made in view of such a problem, and an object thereof is to reduce a calculation load at the time of display while suppressing a reduction in the reality of a three-dimensional map.

The present invention
A three-dimensional map display system for displaying a three-dimensional map representing a three-dimensional feature,
A 3D model database storing a 3D model representing the 3D shape of the feature;
A synthetic texture database for storing a synthetic texture synthesized by projecting the three-dimensional model after pasting a prepared three-dimensional model texture on each surface of the three-dimensional model;
The three-dimensional model corresponding to the display range of the three-dimensional map is arranged in a virtual three-dimensional space, and the synthetic texture corresponding to the three-dimensional model is opposite to the projection direction at the time of synthesis on the three-dimensional model. A synthetic texture projection part that projects in the direction,
A three-dimensional map display system including a display control unit that projects the three-dimensional model projected with the composite texture and displays the three-dimensional map can be configured.
Projection is a technique called projection. By projecting each pixel on the composite texture as a two-dimensional image onto a three-dimensional model along a straight line in the projection direction, a planar texture image can be pasted on the three-dimensional model with unevenness.

In the present invention, not a texture for a 3D model but a composite texture obtained by synthesizing the texture is projected onto a 3D model to display a 3D map. In general, in the display of a three-dimensional map, the load required for texture processing becomes so high that it cannot be ignored, and the load varies depending on the resolution and number of textures. On the other hand, in the present invention, since the synthetic texture is used, the number of textures can be reduced. In addition, since this synthetic texture is generated by applying a 3D model texture to a 3D model and projecting it, even if the 3D model texture has a high resolution, The resolution can be reduced. With these effects, according to the present invention, it is possible to reduce the load of processing the texture in the three-dimensional map display.
When such a synthetic texture is used, the synthetic texture is generated by projection, so that a hidden surface that cannot be visually recognized from the projection direction is generated. However, in the present invention, since the projection is performed in the direction opposite to the projection direction at the time of synthesis, there is an advantage that the influence of the hidden surface when using the synthesized texture can be suppressed.

The map display in the present invention can be performed on various displays such as a computer, a smartphone, other portable terminals, and a navigation device.
The 3D map display system may be configured as a system that simply displays a 3D map as a still image, or may be configured as a system that dynamically displays a 3D map in the course of route guidance.
In the present invention, either the perspective projection or the parallel projection may be used as the projection when generating the synthetic texture.
Moreover, you may produce | generate the synthetic | combination texture of this invention per feature unit. For example, in the case of a building, a texture for a three-dimensional model is attached to each surface such as a side surface and an upper surface, but if this is projected, the whole is combined into one texture combined, so the number is reduced. be able to.

In the present invention, the projection direction when displaying a three-dimensional map (hereinafter also referred to as “projection direction during display”) is the projection direction when generating a composite texture (hereinafter referred to as “projection direction during generation”). Need not match). However, if the 3D map is displayed in a direction different from the projection direction when generating the synthetic texture, the above-described influence of the hidden surface appears, and the portion where the texture is not affixed on the 3D map (hereinafter referred to as “model exposed portion”) May be displayed). In order to suppress such influence, it is preferable that the projection direction during display and the projection direction during generation be close to the extent that the model exposure portion does not appear remarkably. The three-dimensional projection direction can be expressed by the direction in the horizontal plane, that is, the projection azimuth and the angle between the horizontal plane, that is, the pitch angle. In order to prevent the model exposure portion from appearing significantly, It is preferable that the projection azimuth be closer to the time of display and generation than the pitch angle.
As another method for suppressing the influence of the model exposure part, a 3D model texture is affixed to the hidden part of the composite texture so that the influence of the hidden surface is avoided and the 3D map is displayed. It may be.

In the three-dimensional map display system of the present invention,
The display control unit may display the three-dimensional map by projecting in substantially the same direction as the projection direction at the time of synthesis (that is, the generation projection direction).
By carrying out like this, as above-mentioned, the influence of a hidden surface can be suppressed. The “substantially same orientation” refers to a range in which a model exposed portion to which a texture is not attached is not significantly displayed on the three-dimensional map display. Depending on the generation of the synthetic texture and the display scale when displaying the three-dimensional map, for example, the same direction can be within a range of about plus or minus 22.5 degrees.

In the three-dimensional map display system of the present invention,
The synthetic texture is generated by arranging a plurality of the 3D models to which the texture for the 3D model is attached according to a geographical positional relationship, and projecting the arranged 3D models.
The synthetic texture projecting unit may project the synthetic texture on the plurality of three-dimensional models.
In this aspect, by projecting a “town” in which a plurality of three-dimensional models are arranged, these are combined into one synthetic texture. In this way, the number of textures can be reduced and the resolution can be reduced as compared with the case of projecting a single 3D model, as compared to the case where the 3D model is individually made as a composite texture. It is possible to reduce the calculation load associated with.

In the three-dimensional map display system of the present invention,
The synthetic texture may be generated by parallel projection.
Since perspective projection is a projection method performed by specifying a viewpoint position and a line-of-sight direction, the viewpoint when projecting a three-dimensional map is different from the viewpoint when generating a synthetic texture in the synthetic texture generated thereby. In some cases, hidden surface effects may appear. On the other hand, since the parallel projection can project without defining the “viewpoint position” if the projection direction is defined, the viewpoint for displaying the three-dimensional map can also be arbitrarily selected. There are advantages.
In perspective projection, a three-dimensional model far from the viewpoint collapses very small during projection, and information is lost on the composite texture. In parallel projection, this effect can be avoided. There is also.
As a result, when parallel projection is used, a wide range of synthetic textures can be generated up to the whole of Japan, and when displaying a 3D map, any part of it can be cut out and used. Thus, the data volume and management load of the composite texture can be suppressed.
When the synthesized texture is generated by parallel projection, projection of the synthesized texture is also performed by parallel projection in order to map it on the three-dimensional model with high accuracy. On the other hand, the display of the three-dimensional model can be selected regardless of the projection method at the time of generating the synthetic texture, and may be performed by either parallel projection or perspective projection.

In the three-dimensional map display system of the present invention,
The synthetic texture database stores a plurality of types of synthetic textures generated in a projection direction from a plurality of directions for one region,
The synthetic texture projection unit may perform the projection using a synthetic texture generated in a projection direction close to the projection direction performed by the display control unit.
As described above, by selecting the composite texture generated with the generation projection direction close to the display-time projection direction, it is possible to suppress the influence of the hidden surface generated when generating the composite texture.
The direction in which the synthetic texture is to be prepared can be arbitrarily set in consideration of the influence of the hidden surface described above, and can be, for example, about eight directions.

The present invention is not limited to a mode as a three-dimensional map display system, and can also be configured in the following mode.
That is, a synthetic texture generation device that generates a synthetic texture used to display a three-dimensional map that represents a three-dimensional feature,
A map database for storing data of a three-dimensional model representing a three-dimensional shape of the feature, and a plurality of textures for a three-dimensional model to be affixed to a plurality of surfaces of the three-dimensional model;
Based on the map database, a synthetic texture generation unit that generates the synthetic texture;
A synthetic texture database for storing the generated synthetic texture;
A database management unit that stores the generated synthetic texture in the synthetic texture database in association with the three-dimensional model to be generated;
The synthetic texture generation unit
Affixing the texture for the 3D model on each surface of the 3D model;
It is an aspect with the synthetic | combination texture production | generation apparatus which produces | generates the said synthetic | combination texture by projecting the said three-dimensional model.

According to the above aspect, a composite texture can be generated using the 3D model and the 3D model texture.
Parallel projection, perspective projection, or the like can be used as the projection when generating the synthetic texture. The synthetic texture may be generated for each single 3D model or may be generated for a city where a plurality of 3D models are arranged. In addition, various feature points described in the three-dimensional map display system can be reflected in the synthetic texture generation apparatus.
If the projection direction at the time of displaying the three-dimensional map display is known, that direction may be used when generating the synthetic texture. When the display projection azimuth is not fixed, the generation projection azimuth may be set arbitrarily, and it is preferable to generate a plurality of types of synthetic textures in a plurality of directions.
Various methods can be used for associating the synthetic texture with the three-dimensional model. For example, when a synthetic texture is generated for a single three-dimensional model, both may be associated with each other on a one-to-one basis. When synthetic textures are generated for a plurality of three-dimensional models, information for associating a plurality of three-dimensional models to be generated with synthetic textures may be prepared, or as a map maintenance unit A region / region where a three-dimensional model is arranged, such as a rectangular region called a mesh, and a synthetic texture may be associated with each other.

The present invention does not have to include all the above-described features, and may be configured by omitting a part or combining them as appropriate.
In addition to the configuration as a three-dimensional map display system, the present invention can also be configured as a three-dimensional map display method for displaying a three-dimensional map by a computer and a synthetic texture generation method for generating a synthetic texture. Furthermore, a computer program for causing a computer to implement these methods, and a computer-readable recording medium recording the computer program (including various computer-readable media such as a magneto-optical disk, a flash memory, and a hard disk) You may comprise as.

It is explanatory drawing which shows the display method of the three-dimensional map in an Example. It is explanatory drawing which shows the structure of a route guidance system. It is explanatory drawing which shows the production | generation method of a synthetic | combination texture. It is explanatory drawing which shows the production | generation example of a synthetic | combination texture. It is explanatory drawing which shows the example of a display of the three-dimensional map using a synthetic | combination texture. It is explanatory drawing which shows the structure of a synthetic | combination texture database. It is a flowchart of synthetic texture generation processing. It is a flowchart of a route guidance process. It is a flowchart of a synthetic | combination texture selection process.

Taking a case of a route guidance system as an example, embodiments of the three-dimensional map display system and the synthetic texture generation device of the present invention will be described.
A. How to display a 3D map:
FIG. 1 is an explanatory diagram illustrating a method for displaying a three-dimensional map in the embodiment. The three-dimensional map display is performed according to a procedure from the upper level to the lower level in the figure.
The upper part shows the process of generating a synthetic texture as pre-processing. In this embodiment, a three-dimensional model M1 representing the three-dimensional shape of the feature is prepared. The three-dimensional model M1 is provided with image data such as three-dimensional model textures (hereinafter also simply referred to as “textures”) T1, T2, and the like indicating the appearance. This is because only the textures T1 and T2 are shown in the figure, but texture images are also prepared in the hidden parts in the figure.
At the time of generating a synthetic texture, textures T1, T2, etc. are pasted on the surface of the three-dimensional model M1, and a projection view T3 is created by parallel projection. The projection direction of parallel projection, that is, the generation projection direction PRJ1 can be arbitrarily set. In the state before projection, a plurality of textures including textures T1 and T2 are attached to the three-dimensional model M1, but the projection image T3 is a single two-dimensional image. The projection image T3 generated in this way is called a synthetic texture T3 in this embodiment. In the present embodiment, this synthetic texture T3 is generated and stored as a database in advance as preprocessing for displaying a three-dimensional map.

The processing after displaying the three-dimensional map is shown after the middle. First, a three-dimensional model M1 to be displayed is placed in a virtual three-dimensional space. Then, the previously generated synthetic texture T3 is projected onto the three-dimensional model M1. The projection direction PRJ2 is 180 degrees opposite to the projection direction PRJ1 when the synthetic texture T3 is generated. Projection is a technique for mapping each pixel of the composite texture T3 onto the surface of the three-dimensional model M1 along the projection direction PRJ2. By the projection of the synthetic texture T3, the surface of the three-dimensional model M1 has the same appearance as when the textures T1 and T2 are pasted. This state is referred to as a three-dimensional model M2.
Since a single composite texture is used in the projection, the same appearance as when the textures T1 and T2 are pasted is realized by the single composite texture T3. Further, since the synthetic texture T3 is generated by parallel projection of the three-dimensional model M1, the synthetic texture T3 has a lower resolution than the textures T1 and T2 depending on the projection scale at that time. If it demonstrates along the example in a figure, the case where the three-dimensional model M1 is arrange | positioned in the state reduced rather than the model prepared originally should be considered. Even in such a case, the textures T1 and T2 are used with a high resolution, but the synthetic texture T3 generated by projecting the textures has a low resolution.
Thus, by the projection processing shown in the middle stage, the three-dimensional model M2 is a model to which a texture with a resolution reduced according to the size of the single three-dimensional model is attached. However, since the synthetic texture T3 includes only a surface that can be visually recognized by the projection processing at the time of generation shown in the upper part and does not include the appearance of the hidden surface, Is an exposed surface where no texture is applied, that is, the polygon of the three-dimensional model is exposed as it is.

The lower part shows a process of displaying a three-dimensional map using the three-dimensional model M2. The projection image PM can be displayed by perspectively projecting the three-dimensional model M2 onto the projection plane PV as indicated by an arrow PRJ3 according to a predetermined viewpoint and line-of-sight direction. It is preferable that the line-of-sight direction during display, that is, the projection direction during display is substantially the same as the projection direction PRJ1 during generation. By doing so, it is possible to suppress the possibility that an exposed surface to which the synthetic texture T3 is not attached in the three-dimensional model M2 is drawn in the projection image PM.
In the present embodiment, as described above, a method of generating a synthetic texture as preprocessing and pasting it is used to display a three-dimensional map.

In the above example, the generation and projection of the composite texture uses parallel projection, but this may be performed by perspective projection. The display of the three-dimensional map can be performed by parallel projection in addition to perspective projection.
In the above example, a single three-dimensional model has been described as an example. However, a synthetic texture can be generated for an area in which a plurality of three-dimensional models are arranged. Since a three-dimensional map is prepared with a rectangular area of a predetermined size called a mesh as a management unit, a composite texture is generated in this mesh unit also in this embodiment.

B. System configuration:
B1. overall structure:
FIG. 2 is an explanatory diagram showing the configuration of the route guidance system. Based on the map data provided from the server 200 via the network NE2 or the like, a configuration example is shown in which a map is displayed on the smartphone 300 and route guidance is performed. As a terminal for displaying a map, a personal computer, a navigation device, or the like may be used. Moreover, you may comprise a route guidance system as a system which operate | moves stand-alone besides the system which consists of a terminal like the smart phone 300, and the server 200. FIG.
In the figure, a synthetic texture generation apparatus 100 that generates synthetic texture data is also shown.

The smart phone 300 includes various functional blocks that operate under the main control unit 304. In the present embodiment, the main control unit 304 and each functional block are configured by installing software that realizes the respective functions, but part or all of them may be configured by hardware.
The transmission / reception unit 301 communicates with the server 200 via the network NE2. In the present embodiment, transmission / reception of map data and commands for displaying a three-dimensional map is mainly performed.
The command input unit 302 inputs an instruction from the user through an operation on the smartphone 300 or the like. As an instruction in the present embodiment, a display range of a three-dimensional map, designation of enlargement / reduction, setting of a starting point and a destination when performing route guidance, and the like are listed.
The GPS input unit 303 obtains latitude and longitude coordinate values based on a GPS (Global Positioning System) signal. In the route guidance, the traveling direction is calculated based on changes in latitude and longitude.
The map information storage unit 305 is a buffer that temporarily stores map data provided from the server 200. When a map to be displayed moves from moment to moment as in route guidance, the map information storage unit 305 receives map data in an insufficient range from the server 200 and displays the map.
The composite texture projection unit 306 projects the composite texture onto the three-dimensional model (see interruption in FIG. 1) when mapping.
The display control unit 307 displays a three-dimensional map on the display 300 d of the smartphone 300 based on data provided from the map information storage unit 305 and the synthetic texture projection unit 306.
Some of the functions provided in the smartphone 300 may be realized by the server 200.

The server 200 includes functional blocks shown in the figure. In the present embodiment, these functional blocks are configured by installing software that realizes the respective functions, but a part or all of the functional blocks may be configured by hardware.
The map database 210 is a database for displaying a three-dimensional map. In this embodiment, map data including a 3D map database 211, a synthetic texture database 212, and network data 213 is stored. The 3D map database 211 is data for displaying three-dimensional features such as roads and buildings, and is two-dimensional polygon data obtained by parallel projection of a three-dimensional model of the features. The synthetic texture database 212 is data such as characters to be displayed on the map, such as names of features and names of places. The network data 213 is data representing a road as a collection of nodes and links. A node is data corresponding to an intersection of roads or an end point of a road. A link is a line segment connecting nodes, and is data corresponding to a road. In the present embodiment, the positions of nodes and links constituting the network data 213 are determined by three-dimensional data of latitude and longitude and height.
The transmission / reception unit 201 transmits / receives data to / from the smartphone 300 via the network NE2. In the present embodiment, transmission / reception of map data and commands for displaying a three-dimensional map is mainly performed. The transmission / reception unit 201 also performs communication with the synthetic texture generation apparatus 100 via the network NE1. In this embodiment, the generated synthetic texture is mainly exchanged.
The database management unit 202 controls reading of data from the map database 210. In addition, the composite texture received from the composite texture generation apparatus 100 has a function of storing the composite texture in the composite texture database 212 in units of meshes.
The route search unit 203 performs route search using the network data 213 in the map database 210. A Dijkstra method or the like can be used for the route search.

The synthetic texture generation apparatus 100 is configured with functional blocks shown in the figure. In this embodiment, these functional blocks are configured by installing software that realizes the respective functions in a personal computer, but a part or all of the functional blocks may be configured by hardware.
The transmission / reception unit 105 exchanges data with the server 200 via the network NE1.
The command input unit 101 inputs an operator instruction via a keyboard or the like. In the present embodiment, specification of a region where a synthetic texture is to be generated, designation of parallel projection parameters when generating a synthetic texture, and the like are included.
The 3D map database 104 is a database that stores a three-dimensional model and a texture for a three-dimensional model (hereinafter simply referred to as “texture”) used to generate a composite texture. For features such as roads and buildings, electronic data representing a three-dimensional shape and its appearance are stored. The 3D map database 104 can use data for displaying a three-dimensional map by perspective projection.
Based on the 3D map database 104, the synthetic texture generation unit 102 performs display by parallel projection and generates a synthetic texture. The generated synthetic texture is stored in the synthetic texture holding unit 103 and then stored in the synthetic texture database 212 in the map database 210 of the server 200 via the transmission / reception unit 105.

B2. Synthetic texture:
Next, the contents of the synthetic texture used in this embodiment and the structure of the synthetic texture database will be described.
FIG. 3 is an explanatory diagram showing a synthetic texture generation method. In this embodiment, a composite texture is generated by applying a texture to the surface of the three-dimensional model M3 and performing parallel projection. At this time, parallel projection is performed with respect to a projection direction inclined obliquely from the vertical direction.
The meaning of projecting obliquely is as follows. The lower part of the figure shows how two-dimensional projection images D1 and D2 are obtained from the three-dimensional map data D3 by parallel projection. The three-dimensional data D3 is data representing the shape of the three-dimensional model M3 representing a building on the plane P3 with three-dimensional coordinates of x, y, and z.
When this three-dimensional model M3 is parallel-projected onto a plane P1 in the vertical direction (in the direction of arrow A1 in the figure), the three-dimensional model M3 becomes a projection image D1 expressed two-dimensionally as a rectangle M1. This corresponds to conventional two-dimensional map data.
On the other hand, in this embodiment, parallel projection is performed on a plane P2 in an oblique direction (in the direction of arrow A2 in the figure) inclined by a predetermined projection angle with respect to the vertical direction. As a result, on the projection image D2, a building is displayed three-dimensionally like a building M2. Although the building M2 is expressed three-dimensionally, the projection image D2 is only projected two-dimensional display data. The composite texture of the present embodiment is a texture that represents a three-dimensional appearance including the side surfaces by generating by the parallel projection in the oblique direction as described above.
The projection direction in the case of oblique parallel projection can be expressed by a combination of a projection direction that is an angle in the xy plane and a pitch angle that is an angle formed by the xy plane. This projection azimuth and pitch angle may be referred to as projection parameters in this specification.
The synthetic texture can be generated individually for each building. However, in this embodiment, the synthetic texture is generated for each mesh that maintains the three-dimensional map database 104. The upper part of FIG. 3 shows an example of the synthetic texture TEX generated in this way. As shown in the figure, a plurality of three-dimensional models such as buildings BLD1, BLD2, and BDL3 stored in the three-dimensional map database 104 are arranged, and a texture prepared for each three-dimensional model is pasted on the surface. Thus, the composite texture TEX is generated by performing parallel projection. The composite texture TEX is a two-dimensional image including a plurality of buildings BLD1, BLD2, BDL3, and the like. By using the parallel projected projection images in this way, it is possible to represent a plurality of textures attached to each three-dimensional model before projection by a single composite texture TEX. Also, the texture to be applied to the 3D model is often generated at a high resolution so that the appearance can be accurately expressed even when the 3D model is enlarged. By projecting the included area, the synthetic texture TEX can reduce the resolution to an extent suitable for displaying the area.

In this embodiment, a composite texture is generated with a plurality of projection directions for one region. The significance will be explained.
FIG. 4 is an explanatory diagram illustrating an example of generating a synthetic texture. As described with reference to FIG. 3, the composite texture is a single two-dimensional image generated by parallel projection.
FIG. 5 is an explanatory diagram illustrating a display example of a three-dimensional map using a synthetic texture. Display examples in the case where the synthetic texture shown in FIG. 4 is pasted on the surface of the three-dimensional model and then perspective projected are shown in the upper and lower stages, respectively. Each is a three-dimensional map representing a common area A as shown in the middle of the figure, but the projection in the perspective projection is different such that the top is the direction of the arrow V1 and the bottom is the direction of the arrow V2. .
The azimuth of the arrow V1 shown in the upper stage is the same projection azimuth as the parallel projection when generating the composite texture shown in FIG. Therefore, if the synthetic texture is pasted on the surface of the three-dimensional model and then projected in perspective, a three-dimensional map with no particular sense of incongruity can be displayed. The reason why the buildings displayed in FIGS. 4 and 5 are different is that the pitch angle is different between when the synthetic texture is generated and when the three-dimensional map is displayed. As described above, when the projection direction is almost the same when generating the synthetic texture and when displaying the three-dimensional map, even if the pitch angle and the projection method are different, it is possible to display a three-dimensional map without any sense of incongruity. it can.
On the other hand, when projected from the azimuth of the arrow V2, as shown in the lower part, model exposed portions to which textures are not applied, that is, black portions in the figure, appear at various locations on the three-dimensional map. For example, when looking at the building B, in the upper diagram, no black portion is drawn on the appearance, whereas in the lower diagram, the model exposed portion S appears. The reason why the model exposed portion S appears is as follows. Since the synthetic texture is generated by projecting the three-dimensional model in parallel to the projection direction, a hidden surface that cannot be visually recognized from the projection direction is not drawn in the synthetic texture. Therefore, even if this synthetic texture is projected onto the three-dimensional model, no synthetic texture is applied to the hidden surface. When the 3D model in such a state is used for displaying a 3D map, if the projection direction at the time of display is substantially the same as the projection direction at the time of generating the synthetic texture, the hidden surface does not appear on the 3D map. (Upper part of FIG. 5), if they are different, the surface without the synthetic texture is drawn to generate a model exposed part (lower part of FIG. 5).
In this embodiment, since a three-dimensional map can be displayed in various projection directions without generating a model exposed portion, the composite texture is also generated in a plurality of projection directions with respect to a single region. .

FIG. 6 is an explanatory diagram showing the structure of the synthetic texture database. The upper part of the figure shows the projection direction for generating the composite texture. As shown in the figure, in this embodiment, the orientation is shifted by 45 degrees with respect to one mesh AR, and parallel projection is performed for each of the eight orientations from orientation 1 to orientation 8, thereby generating a composite texture. For example, in orientation 1, a composite texture obtained by parallel projection when viewed from the north side is obtained, and in orientation 5, a composite texture obtained by parallel projection when viewed from the south side is obtained. Buildings that were blind in azimuth 1 will not be blind in azimuth 5 in the opposite direction. The combined texture of each direction is attached with identification information of TEX1 to TEX8 and is stored as an individual image file.
In this embodiment, a composite texture with 8 orientations is prepared, but it may be 4 orientations or 16 orientations or more. According to the result of the study by the present inventor, if a synthetic texture is prepared in 16 orientations, a model-exposed portion does not appear remarkably and an uncomfortable map can be displayed for any orientation. I know. From this point of view, it can be said that it is preferable to prepare synthetic textures for 16 orientations.
The synthetic texture may be generated at a plurality of pitch angles in each direction.

The lower part shows the data structure of the synthetic texture database.
The mesh ID is identification information that identifies a mesh in which the 3D map database 104 is maintained. In the example of the figure, “AR” representing the area shown in the upper row is stored.
As shown in the upper part, since a composite texture is prepared for each mesh in eight directions, data is stored for each direction in the composite texture database, such as direction 1 and direction 2. As shown in the drawing, the data corresponding to the azimuth 1 stores the pitch angle used when the synthetic texture is generated in the azimuth and the image ID of the synthetic texture. The image ID is identification information of the synthetic texture, and by using this, the image ID can be associated with the synthetic texture image data. Data after the azimuth 2 is also stored in the same structure.
In the present embodiment, the pitch angle is individually stored for each direction, but the pitch angle may be stored as information common to the front direction.

C. Synthetic texture generation processing:
FIG. 7 is a flowchart of the synthetic texture generation process. This processing is performed by the synthetic texture generation unit 102 (see FIG. 2) of the synthetic texture generation device 100, and in terms of hardware, the processing is executed by the CPU of the personal computer that constitutes the synthetic texture generation device 100.
In this embodiment, since the synthetic texture is prepared in units of meshes, when the process is started, the synthetic texture generation apparatus inputs designation of a mesh to be processed (step S100). As the designation method, a mesh-specific index, mesh coordinates, or the like can be used. The synthetic texture generating apparatus 100 may analyze a mesh including the coordinate value of the point designated by the operator on the map and set this as a processing target mesh.

  Further, the synthetic texture generation apparatus 100 inputs parallel projection parameters, that is, a projection direction and a pitch angle (step S101). The parallel projection parameters may be designated by the operator each time a synthesized texture is generated, or a method of setting default parallel projection parameters in the synthesized texture generating apparatus 100 in advance may be used.

  Next, the CPU reads the 3D map database with respect to the target mesh and meshes in a predetermined range around the target mesh, and attaches a texture to each surface of each three-dimensional model included therein (step S102). In this embodiment, 3D map data belonging to meshes within two sections from the target mesh is read. This range can be set arbitrarily. The read 3D map data is temporarily stored in the memory of the synthetic texture generation apparatus 100.

  The synthesized texture generation apparatus 100 performs parallel projection on the read 3D map data based on the parallel projection parameters specified in step S101 (step S103). By this processing, a projection view in which each feature is three-dimensionally expressed by parallel projection is generated and temporarily stored in the memory of the synthesized texture generation apparatus 100. The projection map may be stored as polygon data.

  When the parallel projection is completed, the synthesized texture generation apparatus 100 cuts out a region corresponding to the target mesh from the generated projection map (step S104), and stores it as a synthesized texture in the synthesized texture holding unit 103 (step S105). The composite texture thus stored is transmitted to the server 200 and stored in the composite texture database 212 in association with mesh identification information. By executing the above processing for all meshes, the synthetic texture generation apparatus 100 maintains the synthetic texture database 212 of the present embodiment.

D. Route guidance process:
D1. Overall processing:
Next, a process for performing route guidance while displaying a three-dimensional map using the generated synthetic texture will be described.
FIG. 8 is a flowchart of route guidance processing. The process of the smart phone 300 is shown on the left side, and the process of the server 200 is shown on the right side. These are processes executed by the various functional blocks shown in FIG. 2 in cooperation, and are executed by the CPU of the smartphone 300 and the server 200 in terms of hardware.

First, the user of the smartphone 300 specifies the starting point and destination for route search (step S210). As the departure place, a current position acquired by GPS may be used. The destination can be set by various methods such as a feature name, an address, and a coordinate value of latitude and longitude. The smartphone 300 transmits these designation results to the server 200.
When the designation of the departure point and destination is input (step S200), the server 200 performs a route search using the network data 213 (see FIG. 2) (step S201). For the route search, for example, the Dijkstra method or the like can be used. The server 200 outputs a search result, that is, network data to be a route to the smartphone 300 (step S202).

When the smartphone 300 receives the search result (step S211), the smartphone 300 performs route guidance according to the following procedure.
First, the smartphone 300 inputs the current position and traveling direction of the user (step S213). The current position can be specified by GPS. The traveling direction can be obtained based on a change from the previous position to the current position.
Next, the smartphone 300 performs a synthetic texture selection process (step S220). This process is a process for determining the display range of the map based on the current position and the traveling direction, and selecting the synthetic texture to be used for the map display from the synthetic texture database 212. The specific contents will be described later.

When the synthetic texture is selected, the smartphone 300 projects the synthetic texture after arranging the three-dimensional model stored in the 3D map database 104 in the virtual three-dimensional space (step S230). This process is the process shown in the middle part of FIG. 1, and is a process for mapping the synthesized texture onto the three-dimensional model. The projection direction used for the projection is opposite to the projection direction when generating the composite texture, and alignment with the three-dimensional model is also performed. That is, the composite texture is arranged at a position that exactly overlaps the projection projected in parallel from the three-dimensional model, and projected in the opposite direction to the parallel projection. By doing so, the synthesized texture can be projected onto the three-dimensional model without shifting. In this embodiment, since the composite texture is generated by parallel projection unrelated to the “viewpoint position”, there is an advantage that it can be used in common when displaying a three-dimensional map of any range in the mesh. .
The smartphone 300 performs map display by perspectively projecting the three-dimensional model to which the synthetic texture is attached (step S300). Through the above processing, a three-dimensional map as shown in the upper part of FIG. 5 can be displayed.
In the map, a line indicating the route, a mark indicating the current position, and the like may be displayed. In addition to using synthetic textures, map display is performed by normal perspective projection. For example, these methods can be used by performing perspective projection after arranging polygons representing the path and current position in a virtual three-dimensional space together with a three-dimensional model. Can be displayed. Alternatively, once a three-dimensional map is generated by perspective projection, a polygon representing a route or a current position may be drawn two-dimensionally on the image.
The smartphone 300 performs route guidance by repeatedly executing the processing after step S213 until the user arrives at the destination (step S302). When the map display system statically displays a map without route guidance, the processes of steps S220 to S300 may be executed.

D2. Synthetic texture selection processing:
FIG. 9 is a flowchart of the synthetic texture selection process. This process corresponds to step S220 of the route guidance process (FIG. 8).
The three-dimensional map for route guidance is displayed by perspective projection with the traveling direction as the line-of-sight direction. As described above with reference to FIG. 5, in order to avoid the appearance of the model exposure portion, it is preferable to select a composite texture generated with a projection direction close to the line-of-sight direction of perspective projection.
Therefore, the smartphone 300 first determines the direction of the synthetic texture to be used for the map display based on the traveling direction (step S221). The figure shows how to determine the orientation of the composite texture. The central square area represents an area to be displayed, and eight directions corresponding to FIG. 6 are shown around it. Each azimuth is assigned an angle region of 45 degrees, as indicated by a broken line. The smartphone 300 selects the one including the traveling direction from these eight angle regions. For example, when traveling in the direction indicated by the arrow HD, the azimuth 5 is selected.
The angle region can be determined according to the number of directions in which the composite texture is prepared. If feature data of 16 directions is prepared, it may be 22.5 degrees, and 90 degrees may be used in the case of 4 directions.

As illustrated in the azimuth 1 and the azimuth 8 in the drawing, the angle range assigned to each azimuth may be set to be greater than 45 degrees, and an overlapping area may be provided between the azimuths. A range indicated by a one-dot chain line in the figure represents an angle region wider than 45 degrees. When such a wide angle area is assigned to the azimuth 1 and the azimuth 8, an overlapping area is generated between the two as in the hatched area HA.
By setting in this way, this region can be used as a hysteresis region when determining the orientation. For example, when the traveling direction changes from azimuth 8 to azimuth 1, even when the traveling direction enters the overlapping area HA, the azimuth 8 is used, and conversely, when the traveling direction changes from azimuth 1 to azimuth 8. The direction 1 is used even if the traveling direction enters the overlapping area HA. By providing hysteresis in this way, there is an advantage that it is possible to avoid frequent switching of the composite texture used for display when the traveling direction changes finely near the boundary between the azimuth 1 and the azimuth 8.
In the drawing, an example in which the overlapping area HA is provided between the azimuth 1 and the azimuth 8 is shown, but it is possible to similarly provide an overlapping area between other azimuths.

When the display orientation is thus determined, the smartphone 300 determines the display range based on the current position and orientation (step S222).
An example of determining the display range is shown on the right side of the figure. Consider the case of moving to positions POS1, POS2, and POS3 along a path PS indicated by a broken line. At the position POS1, the range including the width XAr and the vertical YAr is the use range Ar1 of the three-dimensional model to be used for the three-dimensional map display. And since the advancing direction DR1 is right in the figure, ie, corresponds to the azimuth | direction 5 (refer the figure in step S221), the smart phone 300 uses the synthetic | combination texture of the azimuth | direction 5. FIG. When the usage range Ar1 belongs to one mesh, one synthetic texture corresponding to the mesh is used. When the usage range Ar1 corresponds to a plurality of meshes, a plurality of synthetic textures are used. Will be used.

  Next, when moving to the position POS2, the traveling direction DR2 changes slightly to the right. However, since the traveling direction DR2 still belongs to the angle region of the azimuth 5, the smartphone 300 selects the azimuth 5 as the synthetic texture selection azimuth at the position POS2 and determines the usage range AR2. The 3D map itself is projected in a slightly oblique direction with respect to the usage range AR2 by setting the traveling direction DR2 as the line-of-sight direction. However, since the synthesized texture is generated in units of meshes, the usage area to which the synthesized texture is pasted AR2 is set in accordance with the orientation 5.

Next, when moving to the position POS3, the traveling direction DR3 further changes to the right. This traveling direction DR3 deviates from the angular region of azimuth 5 and belongs to the angular region of azimuth 6. Therefore, the smartphone 300 selects the azimuth 6 at the position POS3, determines the usage range AR3 in an oblique direction as illustrated, and pastes the synthetic texture generated in the azimuth 6. At the time of route guidance, the composite texture is switched from the azimuth 5 to the azimuth 6 on the way from the position POS2 to the position POS3.
By performing a three-dimensional map display while selecting a synthetic texture having a direction close to the traveling direction by such processing, it is possible to avoid the deviation of the perspective projection direction from the projection direction at the time of generating the synthetic texture, as shown in FIG. It is possible to avoid the appearance of the exposed model part.

E. Effects and variations:
According to the route guidance system of the embodiment described above, the number and resolution of textures used for map display can be reduced by using a synthetic texture. Therefore, it is possible to reduce the processing load required for the map display while performing the map display by the perspective projection.
The various features described in the present embodiment are not necessarily all provided, and only a part may be realized. Moreover, you may provide an additional function in the content mentioned above.
Needless to say, the present invention is not limited to the above-described embodiments, and various configurations can be adopted without departing from the spirit of the present invention. For example, a part configured in hardware in the embodiment can be configured in software and vice versa. Various modifications shown below can also be configured.
(1) In the embodiment, an example in which the synthetic texture is generated by parallel projection is shown, but this may be generated by perspective projection. In this case, the projection may be performed using the same viewpoint position and line-of-sight direction as the perspective projection.
(2) In the embodiment, an example in which a three-dimensional map is displayed by perspective projection is shown, but a three-dimensional map may be displayed by parallel projection.
(3) In the embodiment, the configuration as a route guidance system is shown, but it is also possible to configure as a three-dimensional map display system that statically displays a three-dimensional map without performing route guidance.
(4) In the embodiment, an example is shown in which, after a 3D model is arranged in a virtual 3D space, a 3D map is displayed without attaching any texture to a hidden surface on which a composite texture is not projected. The texture for the three-dimensional model may be attached to the hidden surface.

  The present invention can be used to display a three-dimensional map that represents a three-dimensional feature.

DESCRIPTION OF SYMBOLS 100 ... Synthetic texture production | generation apparatus 101 ... Command input part 102 ... Synthetic texture production | generation part 103 ... Synthetic texture holding part 104 ... 3D map database 105 ... Transmission / reception part 200 ... Server 201 ... Transmission / reception part 202 ... Database management part 203 ... Path | route search part 210 ... Map database 211 ... 3D map database 212 ... Synthetic texture database 213 ... Network data 300 ... Smartphone 300d ... Display 301 ... Transmission / reception unit 302 ... Command input unit 303 ... GPS input unit 304 ... Main control unit 305 ... Map information storage unit 306 ... Synthetic texture projection unit 307 ... display control unit

Claims (10)

A three-dimensional map display system for displaying a three-dimensional map representing a three-dimensional feature,
A 3D model database storing a 3D model representing the 3D shape of the feature;
A synthetic texture database for storing a synthetic texture synthesized by projecting the three-dimensional model after pasting a prepared three-dimensional model texture on each surface of the three-dimensional model;
The three-dimensional model corresponding to the display range of the three-dimensional map is arranged in a virtual three-dimensional space, and the synthetic texture corresponding to the three-dimensional model is opposite to the projection direction at the time of synthesis on the three-dimensional model. A synthetic texture projection part that projects in the direction,
A three-dimensional map display system comprising: a display control unit that projects the three-dimensional model projected with the synthetic texture and displays the three-dimensional map. The three-dimensional map display system according to claim 1,
The display control unit is a three-dimensional map display system that displays the three-dimensional map by projecting in substantially the same direction as the projection direction at the time of synthesis. The three-dimensional map display system according to claim 1 or 2,
The synthetic texture is generated by arranging a plurality of the 3D models to which the texture for the 3D model is attached according to a geographical positional relationship, and projecting the arranged 3D models.
The synthetic texture projection unit is a three-dimensional map display system that projects the synthetic texture on the plurality of three-dimensional models. It is a three-dimensional map display system in any one of Claims 1-3,
The synthetic texture is a three-dimensional map display system generated by parallel projection. A three-dimensional map display system according to any one of claims 1 to 4,
The synthetic texture database stores a plurality of types of synthetic textures generated in a projection direction from a plurality of directions for one region,
The synthetic texture projection unit is a three-dimensional map display system that performs the projection using a synthetic texture generated with a projection direction close to the projection direction performed by the display control unit. A synthetic texture generation device for generating a synthetic texture used for displaying a three-dimensional map representing a feature in three dimensions,
A map database for storing data of a three-dimensional model representing a three-dimensional shape of the feature, and a plurality of textures for a three-dimensional model to be affixed to a plurality of surfaces of the three-dimensional model;
Based on the map database, a synthetic texture generation unit that generates the synthetic texture;
A synthetic texture database for storing the generated synthetic texture;
A database management unit that stores the generated synthetic texture in the synthetic texture database in association with the three-dimensional model to be generated;
The synthetic texture generation unit
Affixing the texture for the 3D model on each surface of the 3D model;
A synthetic texture generation device that generates the synthetic texture by projecting the three-dimensional model. A three-dimensional map display method for displaying a three-dimensional map representing three-dimensional features,
As steps that the computer performs:
Accessing a 3D model database storing a 3D model representing the 3D shape of the feature;
Accessing a synthesized texture database for storing a synthesized texture synthesized by projecting the three-dimensional model after pasting a prepared three-dimensional model texture on each surface of the three-dimensional model;
The three-dimensional model corresponding to the display range of the three-dimensional map is arranged in a virtual three-dimensional space, and the synthetic texture corresponding to the three-dimensional model is opposite to the projection direction at the time of synthesis on the three-dimensional model. Projecting in the direction,
Projecting a three-dimensional model projected with the synthetic texture to display the three-dimensional map. A synthetic texture generation method for generating a synthetic texture used for displaying a three-dimensional map representing a feature three-dimensionally,
As steps that the computer performs:
Accessing a map database storing data of a three-dimensional model representing a three-dimensional shape of the feature, and a plurality of textures for a three-dimensional model attached to a plurality of faces of the three-dimensional model;
Generating the synthetic texture based on the map database;
Storing the generated synthetic texture in association with the generated three-dimensional model in a synthetic texture database for storing the generated synthetic texture;
The step of generating the synthetic texture includes:
Affixing the texture for the 3D model on each surface of the 3D model;
A synthetic texture generation method for generating the synthetic texture by projecting the three-dimensional model. A computer program for displaying a three-dimensional map representing three-dimensional features,
A function of accessing a three-dimensional model database storing a three-dimensional model representing the three-dimensional shape of the feature;
A function of accessing a synthetic texture database for storing a synthetic texture synthesized by projecting the three-dimensional model after pasting a prepared three-dimensional model texture on each surface of the three-dimensional model;
The three-dimensional model corresponding to the display range of the three-dimensional map is arranged in a virtual three-dimensional space, and the synthetic texture corresponding to the three-dimensional model is opposite to the projection direction at the time of synthesis on the three-dimensional model. The ability to project in the direction,
A computer program for realizing, by a computer, a function of projecting a three-dimensional model projected with the synthetic texture and displaying the three-dimensional map. A computer program for generating a synthetic texture used to display a three-dimensional map representing a feature in three dimensions,
A function of accessing a map database storing data of a three-dimensional model representing a three-dimensional shape of the feature, and a plurality of textures for a three-dimensional model attached to a plurality of faces of the three-dimensional model;
A function of generating the synthetic texture based on the map database;
Causing the computer to realize a function of storing the generated synthetic texture in association with the generated three-dimensional model in the synthetic texture database for storing the generated synthetic texture;
As a function of generating the synthetic texture,
Affixing the texture for the 3D model on each surface of the 3D model;
A computer program that causes a computer to realize a function of generating the synthetic texture by projecting the three-dimensional model.