JP2002304641A - City view display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely display a building to become a land mark, to improve the reality of an entire view, to provide display easy to identify the building to become the land mark, and further to provide smooth display in the case of screen scrolling in a city view display device for three-dimensionally displaying the city view. SOLUTION: A three-dimensional view generating means 30 composed of a computer is provided with a building selecting means 300 having a function for selecting a land mark building and landscape buildings or selecting land mark building candidates and landscape building candidates while giving priority thereto out of building information, which is composed of a plurality of items respectively expressing different appearance shapes, concerning a plurality of buildings and further provided with a function for selecting the building to be displayed according to the priority out of the land mark building candidates and the landscape building candidates within the range of a lamination in the image generating throughput of the city view display device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional display device for a cityscape used in a car navigation system, a geographic information system (GIS), and the like.

[0002]

2. Description of the Related Art Car navigation systems and GIS
(Geographic Information System) etc., a cityscape display device that displays a cityscape three-dimensionally can display the cityscape as much as possible, and can display the cityscape so that the landmark building can be well recognized and identified. Is required. Furthermore, for example, in a case where the viewpoint also moves with movement as in a car navigation system, the screen is scrolled. It is required to be able to display in various forms.

However, when many buildings are displayed, the time required to generate and display an image increases, and the number of screens (frames) that can be displayed per second decreases. In the cityscape display device according to the above, display during movement, that is, smooth display when scrolling the display screen when the viewpoint moves, is sacrificed. In this way, displaying many buildings,
Achieving a smooth display depends on the image generation processing capability of the device (eg, the number of frames that can be displayed per second, or
In terms of the number of drawable polygons per second described later)
There are conflicting demands, and either or both must be sacrificed and compromised to some extent. When smooth display is important when scrolling a screen as in a car navigation system, a method of limiting the number of displayed buildings has conventionally been adopted as shown in the following two examples.

(1) A display area is divided and an area for displaying a building is limited. In the display by the image display means, the display area is not displayed in proximity to the viewpoint from the side closer to the non-display, translucent display,
It is classified into opaque display and distant non-display.

In the proximity non-display area, no building is displayed. Buildings that are close to the viewpoint are displayed larger, so if you display a building that is too close, the buildings behind it are almost
The aim is to prevent this, because it becomes almost invisible.

[0006] Even in the far non-display area, no building is displayed. One of the objectives of providing a far non-display area is to avoid wasting computational resources for rendering an insignificant distant view, which is also a measure to improve screen display speed. This method is similar to the proximity non-display area,
It is used as a general method in 3D computer graphics.

[0007] In the translucent display area, the display target building is displayed translucently. One of the purposes of having a translucent display area is for buildings in this area that are not so far away from the point of view and may hide the buildings behind them,
This is to prevent the building behind it from being hidden. In addition to the translucent display, the display may be a wire frame display or a combination of the wire frame display and the translucent display.

[0008] In the opaque display area, the display target building is displayed opaque. The above method is often used in the three-dimensional building display of the car navigation system. However, by limiting the building display area, the number of displayed buildings is reduced and the display is devised so as to be easy to see.

(2) Select and extract buildings to be displayed.
For example, in Japanese Patent Application Laid-Open No. H5-250420, as can be seen, using the bottom area of a building to select and select a building to be displayed.
We are extracting. The purpose presented here is that when the map is displayed in a reduced size, the display becomes complicated and difficult to see with a simple reduced display.
The building to be displayed is selected and extracted according to the scale, but as a result, the number of displayed buildings is reduced by removing small buildings from the display as unimportant in appearance, and the display is easy to see. It is devised to become.

[0010]

In spite of these efforts, the following problems still remain particularly when a large number of buildings are present, such as in urban areas.

1. Neither a building suitable for a landmark (landmark building: described later) nor a building suitable for cityscape expression (landscape building: described later) was distinguished, and neither display priority was set for both, so it was necessary for navigation, for example. There is a problem in that a landmark building is not displayed, a landmark and a building that is not so important in terms of landscape expression are displayed, and as a result, it is difficult to identify a building useful as a landmark.

2. When a large number of displayed buildings is selected, smooth display when scrolling the screen is hindered. On the other hand, if smooth display is important, not many buildings can be displayed, and not enough landmark buildings are displayed.
The problem was that the cityscape was not well represented.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. In a cityscape display device, even if the image generation processing capability of the device is limited, real-time display can be maintained. While realizing a smooth display when scrolling the screen, reliably displaying buildings suitable as landmarks, and improving the reality of the entire landscape by arranging buildings suitable for appropriately selected landscape expression, It is another object of the present invention to provide a display in which a mark building can be easily identified.

[0014]

According to the present invention, a cityscape display apparatus includes a landmark building which is a building suitable for a landmark and a landscape building which is a building suitable for a representation of a landscape. A building selection means for selecting using the building information having the information, generating a three-dimensional model using the building information for the selected landmark building and the landscape building, and map information having road information and building arrangement information. And a three-dimensional landscape generating means for generating a three-dimensional landscape for the selected landmark building and landscape building from the three-dimensional model, and an image display means for displaying the three-dimensional landscape.

[0015] The cityscape display device according to the present invention is a distance index that is a distance from the viewpoint to the building or a numerical value equivalent thereto, a size index that is a building bottom area or a numerical value equivalent thereto, a height of the building or the number of floors of the building. It is provided with the building selecting means for using at least one of three indices of a height index which is a numerical value corresponding to the above as a selection criterion of the landscape building.

In the cityscape display device according to the present invention, the distance index, the size index, the height index, whether or not the object is a landmark building, or a landmark index indicating a degree of suitability as a landmark building is provided. The apparatus is provided with the building selecting means for using at least one of the landmark buildings as a selection criterion.

[0017] The cityscape display device according to the present invention has the function of selecting the landmark building and the candidate for the landscape building in the building selection means and setting a priority order for the three-dimensional landscape generation. An image generation amount upper limit value for display is set in the three-dimensional landscape generation means, and an image generation amount required for display does not exceed the image generation amount upper limit value from the landmark building candidate and the landscape building candidate. And a function of selecting the landmark building and the landscape building in accordance with the set priority order.

The cityscape display device according to the present invention has the function of selecting the landmark building candidate and the landscape building candidate, and setting a priority order for the three-dimensional landscape generation, in the building selection means. In the three-dimensional landscape generating means, an upper limit of the number of buildings is set to avoid display complexity, and the landmark building candidate and the landscape building candidate are selected so as not to exceed the upper limit of the number of buildings. And a function of selecting the landmark building and the landscape building in accordance with the priority order.

[0019] The cityscape display device according to the present invention has the function of selecting the landmark building candidate and the candidate for the previous landscape building, and setting the priority order for the three-dimensional landscape generation, in the building selection means. In the three-dimensional landscape generating means, the lower limit of the image generation amount is set within the range of the upper limit together with the upper limit of the image generation amount related to the display, and based on the upper and lower limit values of the image generation amount at the time of generating the three-dimensional landscape. Whenever the display screen is generated by the three-dimensional landscape generating means, a temporary upper limit value called a distant limit value is calculated, and necessary image generation is performed when displaying landmark buildings and landscape buildings within the distant limit value. If the amount does not exceed the image generation amount upper limit, select a landmark building candidate and a landscape building candidate within the range of the distant limit value, and if the amount exceeds the image generation amount upper limit, the image generation amount upper limit Beyond To have like, according to the priority, those having a function of selecting landmark buildings and landscape building is then displayed on the screen.

[0020]

Embodiments of the present invention will be described below.

Embodiment 1 FIG. 1 is a block diagram showing a basic configuration diagram of the cityscape display device according to the first embodiment. FIG.
In the figure, 10 is a polygon (polygon) for the bottom shape of the building.
Absolute coordinates of each vertex when approximated by (latitude, longitude, etc.)
Information storing means for storing building information including height and floor number information of buildings and buildings, 20 is map information storing means for storing map information such as road positions and building positions, and 30 is building information and map information And 40, an image display means for displaying the three-dimensional city landscape generated by the city landscape generation means 30. 3D landscape generation means 3
0 is the following software, building selection means 300, 3
It includes a three-dimensional landscape drawing generation unit 310. The three-dimensional landscape drawing generation unit 310 includes a three-dimensional model generation unit 311, a three-dimensional landscape generation unit 312, and a drawing unit 313.

The building information storage means 10 and the map information storage means 20 are composed of various storage devices and building information and map information stored therein. Examples of various storage devices include a hard disk device, a CD-ROM device, a floppy (registered trademark) disk device, and a silicon (disk) (including a smart media, a memory stick, a flash memory card, and the like). Although the building information storage means 10 and the map information storage means 20 are described as being independent in FIG. 1, they need not necessarily be independent devices. The areas may be stored separately in the same storage device.

Although not explicitly shown in FIG. 1, the cityscape generating means 30 has a CPU (Central Processing Unit) and a work area (memory), and has a building information storage means 10, a map information storage means 20, and an image display. Means for exchanging data with the means 40, including time management,
It has a function of setting and supporting an operation environment in the three-dimensional model generation means 311, three-dimensional landscape generation means 312, and drawing means 313 included in 0. For example, the three-dimensional model generation unit 311, the three-dimensional landscape generation unit 312, and the drawing unit 313 are usually all configured by software, but the CPU (central processing unit) and the work area ( The provision of a memory) and management of a series of processes are performed by the cityscape drawing generation means 30. Further, an input unit such as a cursor, a mouse, a joystick, and a cross button may be provided so that a user can input data as needed. The image display means 40 can be composed of a graphic processor and a liquid crystal display, or a video card with a three-dimensional high-speed display function and a CRT display.

In FIG. 1, the building information storage means 1
0, a bold line connecting the map information storage unit 20, the image display unit 40, and the cityscape drawing generation unit 30 indicates a connection relationship between the components, and a thin line in the cityscape drawing generation unit 30 indicates a flow of information. Alternatively, the flow of processing is shown.

Here, an example of the building information and the map information stored in the building information storage means 10 and the map information storage means 20 will be supplemented. As described above, the map information includes location information of roads, buildings, and the like for each area, and a serial number is assigned to a building included therein for each area. Building information
It is created by giving building information to this serial number for each area. The specific building information is the bottom shape as described above.
(For example, the bottom surface is represented by a polygon, and the coordinate value of each vertex is given.) The height (may be given in the form of the number of floors and the height per floor). Types (office buildings, apartments, detached houses, etc.)
Also, a landmark index and the like described later can be included. In some cases, the location information of the building is included in the building information, and the map information may include only the serial number of the building included therein. Further, the shape of the park may be included in the map information or may be included as building information in a broad sense. Furthermore,
As described above, the map information and the building information may be stored in the same storage unit, or both information may be created and stored as one. In the following, it is assumed that the map information and the building information are stored separately, the map information includes the position information of the building, and the building information includes the base shape, the height, It is assumed that attribute information is included.

The feature of the first embodiment is that the building selecting means 30
0 to automatically select landmark buildings and landscape buildings, and, when the display area of buildings on the screen is divided into multiple areas, the landmark buildings are displayed in a wider display area than the landscape buildings. It is to be displayed.

Prior to describing the operation of the cityscape display device shown in FIG. 1, the display area division at the time of displaying an image on the image display means 40 and the selection of a building for display by the building selection means 300 will be described.

O Display area division As described in the section of the prior art, regarding the way of displaying a building, the display area is arranged in order from a short distance according to the distance from the viewpoint, from a near non-display area to a semi-transparent display area. Opaque display area and distant non-display area. The opaque display area is divided into an opaque required display area and an opaque selection display area in order from the closest one according to the distance from the viewpoint. In the area division, a distance (= distance index) used as an index may be a distance in a sense of Euclidean space from a viewpoint, which is generally used as a “distance”, or may be a three-dimensional value based on the distance. 1-z, which is often used in the field of computer graphics, may be used.

Here, z is one of the coordinate axes of the three-dimensional coordinate system. When using the right hand system, the right thumb takes the x-axis, the index finger takes the y-axis, the middle finger takes the z-axis, and the ground is usually y. In the plane of = 0, the direction of the sky is the direction in which the value of y is positive. In this case, the line-of-sight direction is set on the z-axis, the direction orthogonal to the z-axis and orthogonal to the y-axis is set on the x-axis, and the real coordinates are coordinate-transformed, and the viewpoint coordinates are x = 0, y = 0, z = 1. And In this case, the “numerical value according to the distance” 1-z is the object (coordinates = x, y,
z).

The building display in each display area is as described in the section of the prior art. The opaque essential display area is an area for displaying both a landmark building and a landscape building, which will be described later.
The opaque selection display area is defined as an area that displays only a landmark building. A fixed value may be assigned to a boundary value (distance from the viewpoint or a value equivalent thereto) separating these regions, or some function value may be used. As an example of the latter, when the reduction ratio related to the display is changed, there is a setting method in which the boundary value between the display areas is also changed in inverse proportion to the reduction ratio. The display area of each building can be determined by reading the position of each building from map information or building information.

Note that a building may extend over a plurality of display areas. In this case, the criterion for determining which display area the building belongs to may be determined, for example, based on which display area the representative point of the building belongs to. The representative point of the building may be the point closest to the viewpoint or the center of gravity of the polygon among the vertices of the polygon approximating the bottom of the building. This representative point may be calculated each time, or may be stored in advance as building information.

Selection of Buildings Related to Display The building selecting means 300 selects landmark buildings and landscape buildings from the group of buildings included in the map as follows.

{Landscape Buildings} Buildings suitable for landscape expression and having a building index A that satisfies the criterion A are considered as landscape building candidates, and a distance from the viewpoint (or a value equivalent thereto: a distance index) is selected from the candidates. )
Is defined as being displayed within a predetermined area which is considered appropriate for the scenery among the plurality of display areas divided by.

The designated display area based on the distance index is, for example, a translucent display area or an opaque essential display area. The opaque selection display area is relatively far from the viewpoint and is not important in view of the scenery, and since this area is displayed in a relatively reduced form, displaying many buildings rather increases complexity. Therefore, it is excluded from the display target area of the landscape building.

As an example of the index A according to the criterion A, there is a method of using the bottom area from the bottom shape included in the building information or a value equivalent thereto as a building size index and using this. When the bottom area is the index A, the standard A is that the bottom area is
The building has a certain value or more, for example, a floor area larger than 200 square meters.

The reason why the lower limit value is set for the size index of the building related to the display is that, even when a small building is displayed, the display screen becomes complicated depending on the district, and the landscape is difficult to understand. Of course, by setting the lower limit to 0 square meters, virtually all buildings can be displayed without setting a lower limit, and the lower limit is changed according to the display reduction rate, and displayed. It can be made easier to see according to the reduction ratio of.

When the size index is the index A,
The length of the maximum side of the bottom of the building may be used. This is a landscaped building that has a wide width but a small thickness and not so large in the case of a bottom area. Naturally, it is also possible to select a landscape building together with both the base area and the maximum side length of the building bottom as size indicators.

The above is an example of selecting a landscape building using the size index and the distance index.
A comprehensive selection may be made using a height index, a size index, and a distance index. As described above, when a landscape building is selected, by adding a height index together with a size index and a distance index, various types of landscape buildings can be selected, and the landscape can be expressed better.

{Circle around (1)} Marking Building A building suitable as a marking, and a building index B is selected from landmark building candidates satisfying the criterion B set as being more prominent than the criterion A from the viewpoint (or the The display area is not smaller than the display area of the landscape building, and is considered to be appropriate for displaying the landmark building, and is displayed in the area designated in advance. Is defined as

The designated display areas are, for example, a translucent display area, an opaque essential display area, and an opaque selection display area. In the example of the landscape building, the building selection area is expanded by the opaque selection display area. This is because it is determined that it is necessary to display an area wider than the landscape building in order to make it a landmark.

As an example of the index B according to the standard B, there is a height or floor number (height index) of the building. The reference B in this case is a building having a height index equal to or more than a certain value, for example, a building having 15 floors or more. It is based on the idea that tall buildings are suitable as landmarks. Further, the bottom area of the building or a value equivalent thereto (size index) may be significantly larger than that of the landscape building. For example, one having a bottom area of 1000 square meters or more, and one side of the bottom surface having a length of more than 50 m are used.

Further, a mark or a degree of suitability as a mark may be given to the building information in the building information as a mark index (for example, treated as a kind of attribute information). If the user thinks that the building is very famous, has a characteristic appearance, and is suitable as a landmark building, the landmark index may be added according to the subjectivity. That is, the landmark index can be comprehensively determined and determined by humans in consideration of social factors such as the reputation of the building. Indexing of the degree of suitability as a mark can be realized by giving this as a numerical value. The choice of numbers depends on human subjectivity.

By adopting such a method, even if a building such as the Imperial Palace or the Parliament Building is not selected as a landmark based on the height index or the size index, it is suitable for the landmark because of factors such as the name recognition and unique design. In this case, it is possible to place a mark on the building information or set a mark index by increasing the degree of the mark.

The selection of both the landscape building and the landmark building is performed by a computer, but by setting the landmark index in advance, the building is selected as a landmark building by human judgment.

Further, a height index, a size index, a landmark index,
Further, a distance index may be added, and these may be arbitrarily combined and selected to be used as the index B. For example, when the index B is obtained by multiplying the floor number by the floor area, the index B is close to the total floor area of the building, and is an excellent index indicating the size of the building. If this value is a certain value or more and the building in the display area specified above is selected as a landmark building, the combination of three pieces of information, the height index, the size index, and the distance index, is selected. Then, if a landmark index is added to this, four information are combined and selected.

It is possible that a part of the landscape building overlaps with the landmark building. In this case, it is efficient not to select duplicates, and in practice, duplication does not occur. However, it is not always necessary to perform duplication removal processing.

FIG. 2 is a flowchart for explaining the operation of the cityscape display device shown in FIG. Hereinafter, the operation of the cityscape display device shown in FIG. 1 will be described with reference to FIG.
Steps 1 to 11 are processes in the cityscape generating means 30. In Step 1 of FIG. 2, the viewpoint position and the line-of-sight direction are determined, and which point on the map is to be displayed at the center is determined. For example, in a car navigation system, a GPS (global positioning system) is used to calculate a viewpoint position and a line-of-sight direction by, for example, grasping the current position and traveling direction of a car, thereby determining which point on a map. Decide whether to display with the center. Note that the cursor,
The user may select a viewpoint position and a line-of-sight direction using an input device such as a mouse, a joystick, or a cross button. In Step 2, the range on the map displayed on the image display means 40 is determined from the display center point, the line-of-sight direction thereof, and the specified scale. The above-described display area division (proximity non-display area, translucent display area, opaque essential display area, opaque selection display area, and distant non-display area) is also performed here.

In Step 3, a map of a range to be displayed by the image display means 40 is selected from the map information stored in the map information storage means 20 and read into the cityscape generation means 30. In Step 4, the building included in each display area determined in Step 3 is extracted, and the building information is stored in the building information storage unit 1.
Read from 0.

In Step 5, a distance index, a height index, a size index, and a landmark index are extracted and calculated from the building position, height, bottom shape, and landmark index included in the building information.
In the building selection means 300, the landmark buildings and the landscape buildings are each m, n
Select. The selection criterion is as described above. Here, for example, a building with a base area of 200 square meters or more in the translucent display area and the opaque required display area is set as a landscape building, and the translucent display area, the opaque required display area, and the opaque A building having a height of 15 floors or more in the selected display area is a landmark building.

In Step 6, the three-dimensional model generating means 311 uses the building information such as the bottom shape and the height (or floor number) of the building to generate a three-dimensional model of the building i (= the three-dimensional model i).
And ). The three-dimensional model of the building is a three-dimensional model of the building. For example, a bottom polygon included in the building information is a bottom surface, and a polygonal column having the height of the building is an example of a three-dimensional model of the building. It is. Note that 3
The dimensional model i is generated as opaque and translucent for each display area.

In Step 7, using the three-dimensional landscape generating means 312, the Steward is displayed on the map of the display target range determined in Step 3.
The three-dimensional model i generated in p5 is arranged to generate a three-dimensional landscape i. In Step 8, the drawing unit 313 uses the three-dimensional landscape i
Is generated as a two-dimensional projection view i from the viewpoint. In Step 9, the projection diagram i generated in Step 8 and the projection diagram of the three-dimensional landscape i-1 generated in the previous process are added, and hidden surface processing is performed to obtain a projection diagram of the three-dimensional landscape i.

In Step 10, it is determined whether or not termination is possible, and it is determined whether or not m landmark buildings and n landscape buildings have all been processed in the respective display areas.
The processing shifts to Step 11, and if the processing is not completed, the processing shifts to Step 11. In Step 11, move the target building to the next building
Return to 6. In Step 12, the projection view of the three-dimensional landscape i obtained in Step 8 is displayed on the image display means 40 for each of the landmark buildings and the landscape buildings.

As a result, the projections of the landmark buildings and the landscape buildings are finally divided into semi-transparent and opaque displays for each display area on the map, and the images are arranged at predetermined positions. It is displayed on the display means 40.

FIG. 3 shows an example in which the projection of the three-dimensional landscape generated in this manner is displayed as an image. In FIG. 3, reference numeral 400 denotes a frame of the display screen of the display means 40. Instead of full screen, in multi-window systems,
Becomes the window border. 410 is a horizontal line, 420 is a far non-display area, 430 is an opaque selection display area, 440 is an opaque required display area, 450 is a translucent display area, 460
Is a proximity non-display area. 401 is a landscape building which is in a translucent display area and thus is translucently displayed; 402 is a landscape building which is opaquely displayed because it is in an opaque required display area;
Numeral 403 denotes a landmark building built in the opaque display area.

In this example, a building having a base area of 200 square meters or more in the translucent display area or the opaque essential display area is displayed as a landscape building, and is located in the translucent display area, the opaque essential display area, and the opaque selection display area. , A building with 15 floors or more is displayed as a landmark building. The size, in the translucent display area and the opaque display area,
Since a building that is remarkable in terms of height is displayed, the scenery and atmosphere of the target area are displayed realistically. In the slightly opaque selection display area, a 15-story building or more that serves as a landmark is displayed, but a low-rise landscape building is not displayed. This is because even low-rise buildings in the distance are hidden by the buildings in front of them, meaningless or unnecessary display, making it difficult for the user to recognize and identify them. is there.

According to the present embodiment, as described above, since the functions of the landmark and the landscape can be set independently in the city landscape display, the landmark building can be displayed reliably and the landscape building can be displayed. Is appropriately selected, the reality of the entire landscape is improved, and if this is combined with the selection of the display area, a display in which the landmark building can be easily identified can be performed. Furthermore, since the number of buildings related to display can be effectively reduced, the burden on the image generation processing capability of the device can be reduced, and even if the image generation processing capability of the device is limited, the real-time display performance can be improved. Smooth display can be realized.

Embodiment 2 In the second embodiment, a function of selecting a landmark building candidate and a landscape building candidate and adding a function of setting a priority order regarding the generation of a city landscape is added to the building selection means 300. Regarding the need for priority,
This is due to the limitation of the image generation processing capability of the device.

For example, taking a car navigation system as an example, consider a display while moving. It is assumed that the capability of the apparatus for generating and displaying images is an effective performance of 100,000 polygons (polygons) per second. Assuming that the viewpoint also moves with the movement, the screen scrolls. Therefore, in order to realize a smooth image display with the scroll, a certain number of frames (screens) must be displayed every second. Assume that the required number of frames is 30 frames per second. (At least 12 frames per second are required. If there are 30 frames per second displayed, it looks smooth. At 60 frames per second or more, the difference cannot be recognized by the human eye.) The above-mentioned effective performance is set as the upper limit of the image generation amount of the apparatus. Then, in this case, drawing of 3300 polygons per frame becomes the image generation amount upper limit value. This value is called the upper limit polygon number.

As described above, the upper limit of the image generation amount that can be drawn (hereinafter, referred to as the upper limit polygon number) is determined due to the limitation of the image generation processing capability of the apparatus, so that all the landscape buildings and the landmark buildings are drawn. The required number of polygons
If there is a possibility that the number of polygons will exceed the upper limit, in order to obtain a smooth display, it is necessary to assign a priority to buildings and exclude buildings with lower priorities from drawing objects.

The second embodiment is an embodiment of the invention made to cope with such a situation that the image generation processing capability of the apparatus is limited.

The processing procedure of the second embodiment will be described with reference to the flowcharts of FIGS. The contents of Step 1 to Step 4 in FIG. 2 are the same as in the first embodiment. Regarding Step 5, the building selection means 300 does not select a landscape building and a landmark building, but selects a landmark building candidate and a landscape building candidate, and assigns a priority in the form of a priority number i (details). Will be described later).

Step 6 is the same as that of the first embodiment,
Before moving to p7, Steps 6.1 to 6.4 shown in FIG. 4 are inserted. St
In ep6.1, the number of polygons necessary for projecting and rendering the three-dimensional model i of the building i generated in Step 6 (abbreviated as the number of polygons of the building i) is estimated. (Details will be described later.) Step 6.
In 2, the integrated polygon number i-1 is obtained by adding the integrated polygon number i-1 obtained by integrating the polygon numbers from the building 1 to the building i-1 and the polygon number of the building i estimated in Step 6.1.

In Step 6.3, it is determined whether or not the integrated polygon number i exceeds the upper limit polygon number. If it exceeds, the upper limit of the constraint on the image generation processing capacity has been reached, so the processing after building i is stopped, and the procedure for displaying the building up to i-1 is performed. . If not, since the upper limit of the restriction on the image generation processing capacity has not yet been reached, the process proceeds to Step 7. Step 7 to Step 12 are the same as in the first embodiment.

The priorities of the landscape building candidates are determined by a method of increasing the priority in each display area in accordance with the size of the bottom area (method based on the value of the size index) and a method of increasing the priority closer to the viewpoint. Method (method by the value of the distance index.
However, the proximity non-display area is excluded. ), Etc., at least one of which can be used as an index to determine the order of priority according to the value of the index, or a combination of a plurality of, for example, in each display area, multiply the bottom area and height for each display area (A method of combining a distance index, a size index, and a height index) according to the size of the value.

In the case of a landmark building candidate, a height index,
The landmark index can be added to the size index and distance index, and at least one of them can be used as an index to determine the priority according to the value of the index. Whichever method is used, it is necessary to set selection criteria and determine priorities so that they are at least more prominent than landscape building candidates. In addition,
When assigning priorities, it is necessary to digitize the landmark index in the form of the degree of suitability as a landmark.

The priorities of the landmark building candidate and the landscape building candidate are set independently of each other, and the priority of the landmark building candidate is usually set higher than that of the landscape building candidate. Both priorities may be mixed. As a method of mixing the priorities, a method of converting both priorities into one priority by a certain relational expression may be used.
For example, the priority number of the landscape building candidate is a number multiplied by M, and the priority number of the landmark building candidate is used as it is. When M is increased, the priority of the landmark building candidate increases. By such a method, it is possible to increase the priority of the landmark building candidates and to allow the landmark building candidates to be mixed with the priorities of the landscape building candidates.

The estimation of the number of polygons necessary for drawing the projection of the three-dimensional model i of the building i may be strictly calculated or not necessarily performed. In any case, it is important to shorten the calculation time. As a rough estimation method, the probability of seeing the wall surface is approximately 1/2, so if the number of vertices of the bottom polygon of a certain building is w, the number of side wall surfaces is w, and approximately w / 2 It may be approximated that the surface is visible. In the bird's eye view, you can see the ceiling surface, so you can add 1 to this, and 1 + w / 2 can be estimated as the number of polygons needed to roughly draw the building.

On the other hand, as a slightly strict calculation method, for example, a coordinate system in which the ground is a plane of y = 0 is considered. Side EF of the bottom polygon of the building (however, points E (x1, 0, z1), F (x2, 0, z
2). ) Is perpendicular to the ground, so if the vertex of the bottom polygon is clockwise from the sky, the normal vector can be expressed as (a, 0, b). Here, a = z2-z1 and b = x1-x2.
A plane passing through the point (x1, 0, z1) and having a normal vector as (a, 0, b) is a · (x−x1) + b · (z−z1) = 0. And a ・ (x−
This plane is visible only from the region where x1) + bb (z−z1)> 0.
Therefore, if the viewpoint is (u, v, w), a · (u−x1) + b · (w−z
1) This plane may be visible only from the areas where> 0,
Otherwise you will never see. In this case, the determination can be made by two multiplications and slight addition and subtraction for each side wall surface. To determine whether or not the ceiling polygon is visible, the viewpoint and the height of the ceiling may be compared. If the viewpoint is higher, you can see it and vice versa. Also, the bottom polygon is never visible. With such a calculation, the total number of polygons can be calculated quite precisely.

The priority order is set as a landmark building candidate → a landscape building candidate. For each candidate of the landmark building and the landscape building, for example, if the priority is increased for a small distance from the viewpoint, for example, Even if you exceed the maximum number of polygons for the building with the opaque required display area, all the landmark buildings are displayed,
As for the landscape building candidate, the building closer to the viewpoint is already displayed. When the number of buildings increases in an urban area, the number of landscape building candidates that may not be related to display may increase, and in some cases, some of the landmark building candidates may not be displayed, but they are displayed. In terms of buildings, they have a low display priority and must be allowed.

It is to be noted that there is a method in which the maximum number of polygons is considered a little more flexibly, and for example, even if the number of frames that can be displayed in one second is sacrificed to some extent, all the landmark building candidates are displayed. In this case, between Step 6 and Step 6.1 in FIG. 4, it is determined whether or not the number of landmark building candidates, m, has been reached. If it has not yet been reached, the process proceeds to Step 7; Just add a process to move to. Although some dissatisfaction may remain in terms of smooth display during scrolling, all landmark building candidates will be displayed as landmark buildings.

According to the present embodiment, while the image generation processing capability of the apparatus is limited, even when scrolling the screen, the image generation processing capability can be maintained while maintaining a smooth display that does not cause time delay to the human eyes. Can be used to display as many landmarks and buildings that represent the scenery as possible within that range. Therefore, even when the screen is scrolled in the presence of a large number of buildings, the smooth display, the mark function, and the landscape expression function can be well balanced.

Embodiment 3 The present embodiment is for displaying a display with little flickering when scrolling the screen. An outline of the display screen at the time of scrolling is as follows. Scrolling means moving the viewpoint, but with the movement of the viewpoint, the boundaries of each display area will also move, and the landmark buildings and landscape buildings contained therein will also change. Go. For example, landmark buildings or landscape buildings that belonged to the translucent display area move to the near non-display area and disappear from the display screen when the viewpoint moves forward, and landmark buildings and landscape buildings in the opaque required display area also Because it passes through the proximity non-display area from the translucent display area,
Transparent display from opaque display, then disappears from the display screen. The landmark building in the opaque selection display area transitions to the proximity non-display area via the opaque required display area and the translucent display area, so that after the opaque display continues for a while, it becomes translucent and disappears from the display screen. The landscape building candidate in the opaque selection display area is not displayed at first, but disappears from the screen through the opaque display and the translucent display as it transitions from the opaque required display area to the translucent display area and the proximity non-display area .

As described above, both the landmark building and the landscape building follow the course of appearance, opaque display, translucent display, and disappearance with scrolling.
It follows a single pattern and can be perceived as a natural flow for what you are seeing and does not give you a strange feeling.

However, the building that I wanted to use as a landmark,
Or, when the landscape building disappears or appears unexpectedly, the user feels confused and frequently switches the display / non-display of the building (so-called flickering of the screen), thereby frustrating the user.

In the second embodiment, the priority order is set for the landmark building candidate and the landscape building candidate, so that the necessary buildings can be displayed while the image generation processing capability of the apparatus is restricted. Due to this, a flicker phenomenon that a display / non-display of a specific building is frequently switched when scrolling the screen may occur.

For example, it is assumed that the number of landmark buildings significantly increases and decreases. In such cases, building priority changes frequently occur, and buildings with priority near the display limit will be displayed /
Hiding will be switched frequently. When there are many landmark buildings, there is a possibility that such a landmark building whose display / non-display is frequently switched may appear, but this is generally likely to occur in landscape buildings.

In the third embodiment, in addition to the upper limit polygon number introduced in the second embodiment, a lower limit polygon number and a far limit value are introduced, and in FIG.
Partial correction of ep5 and new addition of Step6.1-6.4. ) Is replaced with Steps 6.1 to 6.7 shown in FIG. 5 to provide a means for reducing display flicker in the above sense.

The lower limit polygon number is set to a value smaller than the upper limit polygon number, for example, a value corresponding to 80% of the upper limit polygon number. As will be described later, the lower limit polygon number is also one of the limiting conditions for the total number of polygons related to the display. Therefore, if the lower limit polygon number is set too small, the number of displayed buildings decreases, and the upper limit polygon number also decreases. If the distance is too close, the effect of reducing the flicker, which means that the display / non-display of a certain building is frequently switched, is reduced. Therefore, an appropriate value should be determined based on a balance between the two effects.

FIG. 2 (however, it is assumed that the third embodiment is modified as described above. That is, in Step 5, priorities of processing are assigned to buildings, and Steps 6.1 to 6.7 are added.) FIG. 5 is a flowchart showing steps 1 to 6.7.

The contents of Steps 1 to 6 and Steps 7 to 12 in FIG. 2 are the same as in the second embodiment. Here, the setting of the building priority in Step 5 sets the priority of the building close to the viewpoint to both the landmark building candidate and the landscape building candidate (however, excludes the non-display area), and sets the landmark building candidate. Shall have a higher priority than landscape building candidates. Steps 6.1 to 6.7 shown in FIG. 5 are inserted between Step 6 and Step 7. Hereafter, Step 6.
1 to 6.7 will be described with reference to FIG.

Step 6.1 and Step 6.2 in FIG.
Is the same as that of FIG. That is, the accumulated polygon number i is calculated up to this point. In Step 6.3, the number of accumulated polygons i is compared with the upper limit polygon number. If the accumulated polygon number i exceeds the upper limit polygon number, the process proceeds to Step 6.6, and if not, the process proceeds to Step 6.4.

In Step 6.4, the distance of the target building i from the viewpoint is set to the already set distant limit value (initial value for the first screen, otherwise, when the previous screen is displayed, If it is smaller than (the far limit value set in Step 6.6), the process proceeds to Step 7, otherwise to Step 6.5.

In Step 6.5, if the total number of polygons i is equal to or larger than the lower limit polygon number, go to Step 6.6.
Move to p7. In Step 6.6, the distance from the viewpoint of the building i when the integrated polygon number i exceeds the upper limit polygon number or when the integrated polygon number i is equal to or larger than the lower limit polygon number is set as a far limit value. Here, the initial value of the far limit value may be any value.

The operation of the apparatus according to the above procedure will be described with a specific example according to FIG. In FIG. 6, the horizontal axis represents the distant limit value (or the distance from the viewpoint), and the vertical axis represents the number of buildings or the number of integrated polygons. Straight line A and straight line B are each in a certain area
For A and B, how the number of buildings to be displayed changes with the distance from the viewpoint is shown. Since the number of buildings on the vertical axis is equivalent to the number of integrated polygons required to display the same, the vertical axis will be treated as the number of integrated polygons. Although the straight lines A and B are monotonically increasing functions, they are straight lines here for the sake of simplicity. In FIG. 6, a horizontal line is drawn by a one-dot chain line at a vertical axis position corresponding to the upper limit polygon number and the lower limit polygon number. The distance (or far limit value) between the intersection of the dash-dot line indicating the number of upper limit polygons and the number of lower limit polygons with the straight lines A and B
Are A1, A2, B1, and B2 as shown in the figure. Further, the initial value of the distant limit value is A0, and A0 is A1 and A2 as shown in FIG.
Assume a value between.

Now, considering a car navigation system,
It is assumed that the vehicle is moving by car from time Ta to Tb, and time Ta
Now, it is assumed that the vehicle has arrived at the region A and at the time Tb at the region B. In this case, from the straight line A, since the total number of polygons at the distance A0 is between the upper limit polygon number and the lower limit polygon number,
The processing of the building related to the display at the time Ta is shown in Step 5 in FIG.
6.4 is the first constraint. That is, processing of buildings within the distance range equal to the distant limit initial value A0 is completed, and the distance
When trying to process buildings beyond A0, see Figure 5, Step 6.
Move to 5. In Step 6.5, since the total number of polygons at the distance A0 exceeds the lower limit polygon number, the process proceeds to Step 6.6, where the distant limit value is set to A0, and for buildings within the range up to the distance A0, Displayed as screen A.

Next, when time Tb has elapsed, the dependency on the distance / polygon number becomes the dependency on the distance / polygon number as shown by the straight line B in FIG. That is, the number of buildings is increasing. The total number of polygons for the distance A0 of the straight line B is shown in FIG.
Because the number of polygons exceeds the upper limit, this time
The upper limit number of polygons in Step 6.3 is the first constraint. That is, in Step 6.3, at a distance B1 smaller than the distant limit value A0, the number of accumulated polygons is equal to or greater than the upper limit polygon number, and the distance B1 at this time is set as the distant limit value,
Buildings within the range up to B1 are displayed as screen B.

Next, it is assumed that the relationship between the number of polygons and the distance is the same as that of the straight line A, for example, when the time Tc has elapsed and the area C has been reached. (It is not necessary to be the same, but this is a measure for simplification of the explanation.) At this time, since the total number of polygons at the distance B1 is smaller than the lower limit polygon number from the straight line A, Step 6.5 in FIG. Is the first constraint condition. That is, the number of processed buildings is increased until the number of accumulated polygons becomes equal to the lower limit polygon number, and when the accumulated polygon number becomes equal to or larger than the lower limit polygon number, the processing of the building ends, and the process proceeds to Step 6.6. The distant limit value is set to A2, and the buildings within the range up to the distance A2 are displayed as the screen C.

In the case of controlling the display / non-display switching only by the constraint condition of the upper limit polygon number according to the second embodiment, when the case of FIG. 6 is applied, the time becomes Ta → Tb → Tc.
As the time elapses, the far limit value greatly changes from A0 to B1 to A1, but according to the third embodiment, the far limit value changes little from A0 to B1 to A2. Therefore,
Because the change is suppressed, the number of buildings related to switching between display and non-display is reduced, and the flicker phenomenon is reduced.

Hereinafter, this point will be described in more detail with reference to FIGS. Here, as in a car navigation system, a case in which the screen is scroll-displayed with movement is assumed.

FIG. 7 shows the time on the horizontal axis and the far limit value on the vertical axis. The distance ranges in which the total number of polygons are equal to the upper limit polygon number and the lower limit polygon number are respectively defined as the upper limit corresponding far limit value and the lower limit value. The corresponding distant limit value is defined, and its time change is shown by a solid line. A large distance limit means that the number of buildings is small. FIG.
Indicates a change in the number of buildings (or the number of integrated polygons) depending on the distance between times T1 and T12 shown in FIG. Here, for simplification, this change is assumed to be a straight line, and each time T1 to T12 is described as a parameter at the right end of the straight line. When the straight line at each time is the same, each time is described as T10 / T11 / T12 or the like at the right end of each corresponding straight line. Each straight line is shown in FIG.
At each time, the upper limit corresponding to the distant limit value and the lower limit corresponding to the distant limit value.

Next, the initial value of the far limit value (any value may be used) is set to, for example, V0. According to FIG. 8, the distance of the straight line T1
The integrated polygon number at V0 is located between the upper limit polygon number and the lower limit polygon number. Therefore, Step 6.4 in FIG. 5 is the first constraint condition, and the processing of the building up to the distance V0 is performed according to FIG. At this time, the determination in Step 6.5 is Yes from FIG. 8, and the process proceeds to Step 6.6. Since the distance at this time is V0, the remote limit value set there remains V0, Does not change from the limit.

At time T2, the far limit set at time T0 is V0, and the far limit set at time T0 is
Because it is located between the upper limit corresponding far limit value at time T2 and the lower limit corresponding far limit value at time T2, for the same reason as at time T1, the far limit value set value at time T2 does not change and V0 Remains.

Similarly, at the times T3 and T4, the set value of the far limit value does not change and remains at V0. In other words, if the far limit value at the previous time is located between the upper limit corresponding far limit value and the lower limit corresponding far limit value at the new time, the newly set far limit value is the previous value. It is unchanged.

Next, consider the time from time T4 to T5.
Looking at the number of integrated polygons at the distance V0 from the straight line T5 in FIG. 8, the value is smaller than the lower limit polygon number. Therefore, in this case, Step 6.5 in FIG. 5 is the first constraint condition, and the range (= distance) of the building to be processed is increased until the number of accumulated polygons exceeds the lower limit polygon number. When the number of accumulated polygons becomes equal to or larger than the lower limit polygon number, the processing is terminated. At this time, the far limit value is a far limit value determined by the lower limit polygon number, that is, the lower limit corresponding far limit value V1 at time T5 in FIG. Is set to

At the following time T6, the situation is the same as at the time T5, and both the upper limit corresponding far limit value and the lower limit corresponding far limit value are larger than the far limit value V1 set at the time T5. Therefore, the far limit value newly set at time T6 is
Is equal to the lower limit value corresponding to the lower limit value V2. Time from time T7
During T9, the distant limit value set immediately before is located between the upper limit corresponding distant limit value and the lower limit corresponding distant limit value, so the distant limit value remains unchanged and remains at V2.

Next, consider the time from time T9 to time T10. In this case, it can be seen from the straight line T10 in FIG. 8 that the upper limit polygon number is exceeded at a distance V3 much smaller than the distance V2. Therefore, Step 6.3 in FIG. 5 is the first constraint condition, and the distance V3 of the building whose accumulated polygon number exceeds the upper limit polygon number is set as the far limit value. At times T11 and T12,
Since the set far limit value is equal to the upper limit corresponding far limit value, the far limit value remains unchanged.

The set distant limit values are indicated by broken lines and circles in FIG. The frequent switching of the display / non-display of a specific building (so-called flickering), which occurs when the number of buildings suddenly increases or decreases when scrolling the screen, while the image generation processing capability of the device is limited, is shown in the figure. Although this is caused by the sudden change of the remote limit value corresponding to the upper limit value of 7, the sudden change of the remote limit value is reduced according to the present embodiment, as shown in the time change of the set remote limit value in FIG. Have been. Therefore,
The flicker phenomenon is alleviated accordingly, and a smooth display with little flicker can be realized even when scrolling the screen.

Embodiment 4 In the cityscape display, the closer the number of displayed buildings is to the number of actual buildings, the higher the reality is, but it is not always better to display many buildings in terms of visibility. If the number of buildings to be displayed is too large, a complicated impression is given, and the display screen becomes difficult to see. In this embodiment, the necessary buildings are displayed so as not to give a complicated impression, and the maximum number of displayed buildings p is introduced as an index of the complexity, and the total number of displayed buildings is limited to within this value. It is something to do.

This embodiment will be described with reference to the flowchart of FIG. In FIG. 2, Step 1 to Step 7 are the same as in the first embodiment. The condition for judging the end of Step 10 is not the total number of buildings m + n shown in Embodiment 1, but the maximum number of displayed buildings p. However, if this value is greater than m + n
It shall be replaced by m + n. In the first embodiment, the landmark buildings and the landscape buildings have been described. However, in this example, the priorities related to the display of the buildings are determined in advance, and not all are displayed. Until determined as, landmark building candidate, landscape building candidate, and in Step 5, each priority has already been determined, since the priority of the normal landmark building candidate is higher than the priority of the landscape building candidate, In this case, among the landscape building candidates n, p−m is the number of landscape buildings related to the display. If pm is greater than n, all landscape buildings are displayed.

The maximum number p of displayed buildings may be a fixed numerical value or may be given as a function value. In addition, the user may select each time. However, if it is a fixed value, the difference is not displayed on the display screen, whether it is a large city or a small city, except for the difference in the size of individual buildings, in cities above a certain size Therefore, there is a problem in displaying the cityscape. On the other hand, when given by a function value, this can be improved. For example, the maximum number of displayed buildings p
With 100 as the lower limit and 500 as the upper limit, during which the number of display candidate buildings (total value of landmark and landscape building candidates) q of 7
0%. In this way, when the number of candidate buildings becomes 100 or more, the number of display buildings changes in proportion to the number of display candidate buildings, so that a display reflecting the cityscape to some extent becomes possible. The setting of the upper limit for the maximum number of displayed buildings comes from the restriction of the image generation processing capacity, and is the same as the reason for setting the upper limit polygon number described in the second or third embodiment.

As an example selected by the user each time,
If any of the landscape building candidates includes a building that you want to use as a landmark, but it is not displayed on the current display screen, if you want to display it and check the positional relationship from your current location, There is a case in which a target building is displayed on a screen by increasing the maximum number of displayed buildings (in some cases, at the expense of smooth display).

As described above, according to the present embodiment, it is possible to prevent the display of the building from becoming more complicated than a certain limit, so that the display can be easily viewed. Also,
As a result, the number of buildings related to the display is reduced, so that a smooth display at the time of scrolling the screen is also improved.

[0103]

The cityscape display device according to the present invention includes a building selecting means for selecting a landmark building which is a building suitable as a landmark and a landscape building which is a building necessary for better displaying the landscape. A three-dimensional model is generated for the selected landmark building and landscape building using the building information, and the selected landmark building and landscape are extracted from the road information, the map information including the arrangement information of the building, and the three-dimensional model. By providing a three-dimensional landscape generating means for generating a three-dimensional landscape for a building and an image display means for displaying the three-dimensional landscape, functions of a landmark and a landscape can be set independently in a city landscape display. Therefore, it is possible to reliably display the landmark buildings, and to improve the reality of the entire landscape by appropriately selecting the landscape buildings.
If this is combined with the selection of the display area, a display in which the landmark building can be easily identified can be performed. Furthermore, since the number of buildings pertaining to display can be effectively reduced in terms of landmarks and landscapes, the load on the image generation processing capability of the device can be reduced. Can improve the real-time display and realize smooth display.

[0104] The cityscape display device according to the present invention provides a distance index that is a distance from a viewpoint to a building or a numerical value equivalent thereto, a size index that is a building bottom area or a numerical value equivalent thereto, a height of a building or a floor number of a building. By providing at least one of the three indices of the height index, which is a numerical value corresponding to the above, as the selection criteria of the landscape building, the selection means of the landscape building or the combination of the selection means is selected. Since the degree of freedom is increased, it is easy to select an appropriate landscape building to express the whole landscape well.

In the cityscape display device according to the present invention, the distance index, the size index, the height index, whether or not a landmark building is used, or the degree of suitability as a landmark building is used as the landmark building selection criterion. 4 of landmark index to show
By providing the building selecting means using at least one of the indices, the degree of freedom in selecting the mark building selecting means or the combination of the selecting means is increased, so that it is easy to select a more appropriate mark building as a mark. become.

[0106] The city landscape display device according to the present invention has the function of selecting the landmark building and the landscape building candidate and setting a priority order for the three-dimensional landscape generation in the building selection means. 3D landscape generation means
An image generation amount upper limit value is set, and the landmark building and the landscape building are selected from the landmark building candidate and the landscape building candidate according to the set priority order so as not to exceed the image generation amount upper limit value. With the function, the image generation processing capacity of the device is limited, and when scrolling the screen, it keeps the smooth display that does not make the human eyes feel a time delay and fills the limit of the image generation processing capacity. It can be used to display as many landmark buildings as possible and buildings that represent the landscape. Therefore, even when the screen is scrolled in the presence of a large number of buildings, the smooth display, the mark function, and the landscape expression function can be well balanced.

[0107] The city landscape display device according to the present invention has the function of selecting the landmark building candidate and the landscape building candidate and setting the priority order for the three-dimensional landscape generation in the building selection means. In the three-dimensional landscape generating means, an upper limit of the number of buildings is set to avoid display complexity, and the landmark building candidate and the landscape building candidate are selected so as not to exceed the upper limit of the number of buildings. By providing the function of selecting the landmark building and the landscape building in accordance with the priority order, it is possible to prevent the building display from becoming more complicated than a certain limit, so that the display can be displayed easily. Further, as a result, the number of buildings related to the display is reduced, so that a smooth display when the screen is scrolled is improved.

[0108] The city landscape display device according to the present invention has the function of selecting the landmark building candidate and the landscape building candidate and setting the priority order for the three-dimensional landscape generation in the building selection means. Setting an image generation amount lower limit value within the range of the upper limit value together with an image generation amount upper limit value for display in the three-dimensional landscape generation means, and when the three-dimensional landscape is generated, the image generation amount upper limit value and the lower limit value; Each time the display screen is generated by the three-dimensional landscape generating means, a tentative upper limit value called a distant limit value is calculated, and a necessary image is displayed when displaying a landmark building and a landscape building within the range of the distant limit value. If the generation amount does not exceed the image generation amount upper limit value, select a landmark building candidate and a landscape building candidate within the range of the distant limit value, and if the image generation amount exceeds the image generation amount upper limit value, select the image generation amount upper limit. The value The function of selecting the landmark building and the landscape building to be displayed next on the screen in accordance with the priority order is provided. Frequent switching of display / non-display of a specific building (so-called flickering), which occurs when there is a sudden increase or decrease in the number of buildings, can be reduced.
As a result, the flicker phenomenon can be improved in addition to the real-time display, and a smoother display can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration diagram of a cityscape display device according to the present invention.

FIG. 2 is a flowchart of the first embodiment.

FIG. 3 is an example of a display screen according to the first embodiment.

FIG. 4 is a flowchart of FIG. 2 showing an additional correction corresponding to the second embodiment.

FIG. 5 is a flowchart of FIG. 2 showing an additional correction corresponding to the third embodiment.

FIG. 6: Relationship between distant limit value and number of buildings (or number of integrated polygons)

FIG. 7 is a temporal change of a far limit value corresponding to an upper and lower limit value and a set value of a far limit value.

FIG. 8 is a relationship between the distant limit value at each time and the number of buildings (or the number of integrated polygons).

[Explanation of symbols]

10 building information storage means, 20 map information storage means,
30 city landscape generation means, 40 image display means, 3
00 Building selection means, 310 3D space drawing generation means, 311 3D model generation means, 312 drawing means, 313 3D space generation means, 400 Display screen frame of display means 40, 401 Translucent display in translucent display area 403, a landscape building displayed opaquely in an opaque required display area, 403 an opaque landmark building displayed in an opaque required display area and an opaque selection display area, 410 a horizontal line, 420 a distant non-display area, 430 opacity selection display area, 440 opacity required display area, 450 translucent display area, 46
0 Proximity non-display area

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2C032 HC08 HC23 2F029 AA02 AC02 AC09 AC13 AC14 AC19 5B050 AA10 BA09 BA17 EA28 FA02 FA09 FA19 5B080 AA13 BA02 CA05 FA09 FA17 GA01 5H180 AA01 FF23 FF27 FF33 FF38 FF39

Claims (6)

[Claims] 1. A building selecting means for selecting a landmark building which is a building suitable as a landmark and a landscape building which is a building suitable for a landscape expression by using building information having a bottom shape and height information of the building. And providing a three-dimensional model of the building using the building information having the bottom surface shape and the height information for the selected landmark building and the landscape building. A city landscape display device comprising: a city landscape generation unit configured to generate a three-dimensional landscape for the selected landmark building and the landscape building from a dimensional model; and an image display unit configured to display the city landscape. 2. A distance index which is a distance from a viewpoint to a building or a numerical value equivalent thereto, a size index which is a building bottom area or a numerical value equivalent thereto, a height which is a numerical value equivalent to a height such as a building height or a floor number of a building. The cityscape display device according to claim 1, further comprising the building selection unit that uses at least one of the three indices as a selection reference for the landscape building. 3. The landmark building comprises at least one of the distance index, the size index, the height index, a landmark building, or a landmark index indicating a degree of suitability as a landmark building. 3. The cityscape display device according to claim 1, further comprising the building selection unit used as a selection criterion. 4. The building selection means has a function of selecting the landmark building candidate and the landscape building candidate, and setting a priority order for the three-dimensional landscape generation. An image generation amount upper limit value for display is set, and from the landmark building candidates and the landscape building candidates, the image generation amount necessary for display does not exceed the image generation amount upper limit value, so that the set priority order. Therefore, the city landscape display device according to any one of claims 1 to 3, further comprising a function of selecting the landmark building and the landscape building. 5. The building selecting means has a function of selecting the landmark building candidate and the landscape building candidate, and setting a priority order for the three-dimensional landscape generation. 4. The apparatus according to claim 1, further comprising a function of setting an upper limit of the number of buildings to avoid display complexity and selecting the landmark building and the landscape building so as not to exceed the upper limit of the number of buildings. 5. 2. The cityscape display device according to item 1. 6. The building selecting means has a function of selecting the landmark building candidate and the landscape building candidate, and setting a priority order for the three-dimensional landscape generation. Along with the upper limit of the image generation amount related to the display, the lower limit of the image generation amount is set within the range of the upper limit value. Each time a display screen is generated, a provisional upper limit called a distant limit is calculated, and when displaying a landmark building and a landscape building within the range of the distant limit, the required image generation amount is the image generation amount upper limit. If not exceed, select landmark building candidates and landscape building candidates within the range of the distant limit value, if exceeding the image generation amount upper limit, so as not to exceed the image generation amount upper limit,
4. The cityscape display device according to claim 1, further comprising a function of selecting the landmark building and the landscape building to be displayed next on the screen based on the distant limit value according to the priority order. 5.