JP5010134B2 - Map data generation apparatus and generation method - Google Patents

Description

  The present invention relates to a method for generating a terrain polygon for representing terrain in electronic map data, and more particularly to a method for generating a terrain polygon representing a rough shape by correcting a terrain polygon representing a detailed shape.

  The electronic map data can display a map at various scales. The electronic map data stores polygons that can display landforms such as land and rivers, and features such as roads and buildings. These polygons are usually prepared hierarchically according to the scale level. That is, as data for displaying an enlarged map with a large scale, lower-level polygons representing the shape of the terrain and features are prepared in relatively detail, and as data for displaying a wide-area map with a small scale, the terrain And higher-level polygons that represent the approximate shape of the feature. There may be an intermediate layer of polygons between them. By preparing polygons of multi-hierarchies with different levels in this way, it is possible to display a map with an accuracy corresponding to each scale while suppressing an increase in time required for map display.

  Conventionally, multi-level map data has been created manually by an operator. First, polygons for detailed display, that is, lower-level polygons are generated based on aerial photographs and survey results. Then, this polygon is simplified by the operator according to the scale, and a high-level polygon is generated. This operation is very complicated, and the processing load on the operator is great.

JP 2003-132353 A

  Conventionally, proposals have been made to automate the process of generating map data in order to reduce the load on the operator. For example, Patent Document 1 discloses a technique for generating data representing a center line of a road using Voronoi division based on a polygon representing the road. Voronoi division is a well-known process in the field of computational geometry, and is a diagram showing the range of power of a plurality of given mother points. In any point within the Voronoi polygon including a certain mother point, the distance to the mother point is shorter than the distance to the other mother point.

  Voronoi division is a process that can be used to line-divide a polygon. However, even if this process is applied to a water system such as a river, a desired schematic shape cannot be obtained. This is because, unlike roads, these water systems are not uniform in width, so the results of Voronoi decomposition are very complex. In the case of an aqueous system, for example, there is a portion that should not necessarily be line-divided just because of its approximate shape, such as the vicinity of the center of a pond. In the technique described in Patent Document 1, there is a possibility that such a region may be uniformly differentiated.

  The above-mentioned problem is not limited to the water system, but the same problem may occur in coastline polygons for representing land, and contour line polygons prepared for painting colors of land according to contour lines according to height. In view of these problems, an object of the present invention is to deform a terrain polygon having a detailed shape used for electronic map data so as to generate a terrain polygon having a substantially shape with a light load.

  The present invention can be configured as a map data generation device that generates a schematic polygon for displaying a schematic shape for a wide-area map from a detailed polygon prepared for an enlarged map and capable of displaying a detailed shape of a terrain. The map data generation apparatus first inputs detailed polygons. The detailed polygon may be stored in advance in the map data generation device, may be provided from a storage medium such as a CD-ROM, or may be provided from a predetermined server via a network. The detailed polygon may be prepared not only for the map data generation device of the present invention but also for electronic map data.

  The map data generation device sets a generating point for Voronoi division from the constituent points constituting the detailed polygon and the generated points generated on the sides of the detailed polygon under predetermined conditions. As the conditions for generating the generation points, for example, a condition that the interval between the generation points is suppressed to a predetermined value or less, a condition that the generation points are provided at points obtained by dividing the polygon configuration points by a predetermined number, and the like are conceivable. Only the points generated in this way may be used as mother points, only the constituent points of polygons may be used as mother points, or both may be used as mother points. The predetermined value or the predetermined number may be determined depending on the scale of the target schematic diagram.

  The map data generation device divides the detailed polygon into Voronois based on the generating points thus obtained. By Voronoi division, a large number of polygons are formed inside and outside the detailed polygon, and vertices that define the polygon are generated. The map data generation device selects a constituent point to be subjected to a deformation process to be performed next based on the distance from each vertex to the mother point obtained by Voronoi division. The distance may be selected based on the magnitude relationship between the distance and the predetermined value, or only those having the minimum or maximum distance from the vertices existing within the predetermined radius are selected, and the Voronoi including the vertex is selected. You may make it select the composing point contained in a polygon. The vertices to be selected in the latter processing may be limited to those existing in the detailed polygon. Next, the map data generation device executes a deformation process, that is, a process of deleting at least a part of the selected constituent points to deform the detailed polygon, thereby generating a schematic polygon.

  According to the map data generation apparatus of the present invention, it is possible to generate a schematic polygon by deleting at least a part of the constituent points of the detailed polygon. The selection of the constituent points to be deleted is performed based on the distance from the vertex of the Voronoi division to the mother point. Since the generating point is a constituent point of the detailed polygon or a point generated on the side, the shape of the polygon is taken into consideration when selecting the constituent point by using the above-mentioned distance as a reference. Therefore, according to the present invention, it is possible to realize an appropriate deformation process according to the terrain to be processed.

  As an example of the deformation process, a degeneration process may be performed. The reduction process is to select a part of the vertices obtained by Voronoi division based on the distance from the vertex to the mother point, and at least part of the detailed polygon is a polygonal line defined based on the selected vertex. Say the process to express. Among the detailed polygons, the constituent points selected in the process described above are deleted. As a result, a part of the detailed polygon is deleted, and a schematic polygon having a shape to which the above-mentioned broken line is connected is generated. In order to reduce the load of deformation processing and avoid the trouble of separating the polygonal line and polygon after deformation, the criteria for selecting vertices when performing degeneration processing and the configuration of detailed polygons It is preferable that the standard for selecting points is unified.

  In the reduction processing, for example, in the above-described vertex selection, a method of selecting a vertex whose distance is equal to or less than half the width of the detailed polygon can be employed. In this way, for example, vertices generated at locations far away from the outer periphery of the polygon, such as near the center of the pond, can be excluded from the degeneration process. The above-mentioned “half” is not a strict value, and the reference value for selection can be set to a value larger than half or a value smaller than half.

  Various settings can also be made for the “detail polygon width”. For example, a value input at the time of processing or a value registered in advance as an attribute value can be used. Further, the maximum width, the minimum width, or the average width of the entire detailed polygon to be processed may be adopted. You may make it measure a width | variety in the area | region of each vertex vicinity.

  The map data generation apparatus may further exclude vertices that form a polygonal line having a predetermined length or less from the selected vertices by reduction processing. By doing so, it is possible to avoid occurrence of a short line due to degeneration. In general, outline polygons are often used on a small scale such as a wide area map. In such a case, the shape displayed by the short line segment is often not recognized, and there is a possibility that it becomes difficult to see the map by displaying this. According to the above aspect, it is possible to avoid occurrence of a short line segment in the degeneration process, and thus it is possible to avoid such an adverse effect.

  As another example of the deformation process, a line segmentation process for expressing at least a part of the detailed polygon with a polygonal line may be executed using the remaining component points from which some of the selected component points are deleted. . By doing so, it is possible to generate a schematic polygon in which a part of the detailed polygon is expressed by a line segment with a lighter load than the reduction process. In the reduction process, a line segment that runs near the center of the detailed polygon is defined, whereas in this aspect, a line segment that extends along the end of the detailed polygon is defined. Therefore, this mode is preferably applied to an area where the width of the detailed polygon is narrow in order to alleviate the uncomfortable feeling of the shape when displayed. From this point of view, for example, the line differentiation process and the reduction process may be properly used according to the width of the detailed polygon.

  The map data generation device of the present invention may display a detailed polygon as a second configuration different from the first configuration described above, and be able to accept designation of an area to be subjected to Voronoi division on the display. . Generating points and Voronoi division are executed for the area thus specified. The degeneration process is performed using the vertices generated in this area. Vertices in the region may be used unconditionally, or as in the first configuration described above, vertices to be subjected to the reduction process may be selected based on predetermined conditions.

  When selecting vertices, for example, after Voronoi division is performed, the result may be displayed superimposed on the detailed polygon, and on the display, designation of a vertex that should be subject to degeneration processing may be accepted. . The degeneration process is performed on the selected vertex. According to such a method, the operator can visually select a vertex, and therefore, it is possible to generate a simple polygon more suitable for a human image.

  The present invention does not have to include all the various features described in the first and second configurations, and some of them may be omitted or appropriately combined. Features in the first configuration may be incorporated into the second configuration, or vice versa. For example, the features in the second configuration may be captured as pre-processing or post-processing of the first configuration. The present invention can be configured as a map data generation method in which map data is generated by a computer in addition to a map data generation device. Moreover, you may comprise as a computer program for performing the production | generation of the map data concerning a computer.

  Furthermore, it can also be configured as a recording medium on which this computer program is recorded. Here, as a recording medium, a flexible disk, a CD-ROM, a magneto-optical disk, an IC card, a ROM cartridge, a punch card, a printed matter on which a code such as a barcode is printed, an internal storage device of a computer (RAM, ROM, etc. Various types of computer-readable media such as a memory) and an external storage device can be used.

Embodiments of the present invention will be described in the following order.
A. Device configuration:
B. Deformation processing:
B1. Voronoi split:
B2. Vertex selection:
C. Preprocessing:
D. Post-processing:
E. Variations:

A. Device configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of a map data generation device 10 as an embodiment. In this embodiment, the map data generation device 10 is configured by installing a computer program for realizing a function as a map data generation device in a general-purpose personal computer. Each functional block in the figure is configured by software, but at least a part may be configured by hardware. In the example of the figure, an apparatus that functions as a stand-alone is illustrated, but the map data generation apparatus 10 may be configured by distributed processing of a plurality of computers connected via a network.

  The map data generation device 10 of the present embodiment has a function of generating new map data using existing map data. It is assumed that polygons representing detailed topography or feature shapes (hereinafter referred to as “detailed polygons”) are prepared as map data in advance for displaying enlarged maps, and these detailed polygons are deformed to create a wide area map. For this display, a polygon representing a schematic shape (hereinafter referred to as “schematic polygon”) is generated. In addition to this, the map data generation device can have various functions such as a function for generating a road network and a function for generating a new polygon. In FIG. Only the part related to the function to generate is shown.

  The map DB 20 stores map data prepared hierarchically. The upper level is data representing a schematic shape for displaying a wide area map, that is, a schematic polygon, and the lower level is data representing a detailed shape for displaying an enlarged map, that is, a detailed polygon. . The number of levels of map data provided in the map DB 20 can be arbitrarily set in consideration of a request for the scale at the time of display and the processing time of display.

  The map DB reference unit 16 refers to the map DB 20 and extracts a polygon to be deformed. The deformation processing unit 15 executes deformation processing of the extracted polygon. Details of the processing will be described later. The deformation DB 21 holds the setting conditions for the deformation processing as a database. The Voronoi division unit 12 executes Voronoi division used in the process of polygon deformation processing in accordance with an instruction from the deformation processing unit 15, and passes the result to the deformation processing unit 15. In addition, various data in the deformation process may be stored in the deformation DB 21.

  The deformation correction unit 14 applies various corrections to the result of the deformation process according to commands from the operator. When it is considered that there is no need to correct or confirm the processing result by the deformation processing unit 15, the deformation correction unit 14 may be omitted. The deformation DB 21 also holds setting conditions for deformation correction processing.

  The display control unit 13 presents an interface screen for inputting the display of the deformed result, the conditions of the deformation, and the like during the deformation process described above. The command input unit 11 inputs a command from an operator through an operation on a keyboard and a mouse.

B. Deformation processing:
FIG. 2 is an explanatory diagram showing an example of deformation processing of river polygons. Detailed polygons are shown on the left, and schematic polygons are shown on the right. Each river polygon is hatched. Originally, the outline polygon is used in a wide area map, so it is drawn with a size smaller than that of the detailed polygon.

  The map data generation device generates a schematic polygon by representing a portion where a river is drawn relatively narrowly, such as a region surrounded by an ellipse in a detailed polygon, with a line. In this way, the process of replacing a polygon with a line is called degeneration (processing). Below, the content of this process is demonstrated.

  FIG. 3 is a flowchart of the deformation process. The deformation processing unit 15 (see FIG. 1) is a process realized in cooperation with other functional blocks, and is a process executed by the CPU of the map data generation device in terms of hardware.

  When processing is started, the CPU displays a map using the map DB 20, and inputs designation of a processing target polygon (step S10). The processing target polygon can be specified by, for example, a method in which an operator clicks on the map with a mouse or the like, or a method of inputting the name of a river to be processed.

  Next, the CPU sets a generating point used for Voronoi division (step S20). The method for setting the generating points is illustrated in the figure. The shape of the river polygon POL is defined by points P1, P2, etc. (hereinafter referred to as “polygon constituent points”) indicated by black circles. First, these polygon composing points P1, P2, etc. are used as mother points as they are. Then, the CPU generates the generation points Pm1, Pm2 by equally dividing the polygon composing points P1, P2, etc. In the example in the figure, the generation points are generated by dividing into three equal parts. These generation points are also generating points.

  The generating point can be generated by various methods regardless of the method described above. For example, the number of divisions may be set for each polygon constituting point P1, P2, etc. so that the distance between the mother points is equal to or less than a predetermined value. Only polygon composing points may be set as generating points, or only generated points may be set as generating points.

  Using the mother point set in this way, the CPU divides the polygon POL and executes a process for generating a Voronoi polygon (step S30). Since the process of dividing into Voronoi polygons is a well-known process in computational geometry, a detailed description is omitted. In the figure, an example of Voronoi polygon processing is shown. By this processing, many vertices of the Voronoi polygon are defined.

  The CPU selects vertices to be used for the reduction process from the voronoi polygon vertices based on a preset reduction condition (step S40), connects these vertices, and also corresponds to the selected vertex. Degeneration processing is performed by deleting the constituent points (step S50). In the example in the figure, for example, the CPU determines that the reduction process should not be performed for the area A indicated by the broken line on the right side of the polygon composing points P4 and P7, and only the area on the left side of this is reduced. Process it. As a result of this processing, as shown in the figure, the polygon POL is represented by the polygon POL1 and the polygonal line CL. A degeneration condition for selecting a vertex to be subjected to degeneration processing will be described later.

  As shown in the figure, the polygonal line CL generated in this way usually has an extremely uneven shape. The CPU resamples and smooths such points on the polygonal line CL (step S60), and completes the process. Resampling means extracting points on the polygonal line CL at an interval coarser than the point line of the polygonal line CL, as indicated by “■” in the figure. By connecting the points thus extracted (“■” in the figure), the broken line CL can be smoothed.

B1. Voronoi split:
FIG. 4 is an explanatory diagram showing an example of Voronoi division processing. The hatched parts in the figure are rivers. As described above, a large number of Voronoi polygons indicated by solid lines can be obtained by setting the generating points indicated by black circles on the contours of river polygons and performing Voronoi division.

B2. Vertex selection:
FIG. 5 is an explanatory diagram showing a method for selecting vertices to be subjected to the reduction process and a result thereof. In this embodiment, the following conditions are set as the degeneration conditions. This degeneration condition is registered in advance in the deformation DB (see FIG. 1).
(Condition 1) A point existing inside the polygon;
(Condition 2) The minimum distance to the generating point is not more than a predetermined value;
The predetermined value was “half of the river width + real number α”. The river width may be input by an operator, but in this embodiment, a value registered in advance in the map DB as an attribute is used. The real number α is a margin for the value of the river width, and can be set arbitrarily. The predetermined value may be set in the form of “half the river width × coefficient”.

  Here, the description will be made on the assumption that the river width is equal to the average width of the river polygons in the region A1 surrounded by the ellipse in the drawing. In the case of the vertex P1 in the figure, the distance to the nearest mother point is obtained as d1 in the figure. Since the vertex P1 is a point inside the river polygon, the condition 1 is satisfied, and if the distance d1 is equal to or less than a predetermined value, the vertex P1 is selected as a target for the degeneration process. On the other hand, for example, the vertex P2 is not selected because the distance d2 to the mother point is larger than a predetermined value. As described above, by providing the above-described condition 2, a vertex far from the edge of the river polygon, such as the vertex P2, is excluded from the object of degeneration. By this process, the vertices marked with white circles in the elliptical areas A1, A2, and A3 are selected as the target of the reduction process. In the drawing, the broken line obtained by the reduction process, that is, the broken line connecting the selected vertices is also shown by a bold line.

  In the above-described selection process, it has been described that the river width serving as a reference for the predetermined value is separately input or registered. On the other hand, the river width may be calculated from the river polygon by the following method, for example. First, distances L1, L2, and L3 of the generating point M from the surrounding generating points are obtained. From this, a point that is not on the same edge line of the polygon point M and the polygon is selected, and the distance is set as the river width at the mother point M. In the example of the figure, the distance L3 is set as the river width. This process is executed for all generating points, and the river width of the river polygon is set with representative values such as the maximum value, minimum value, and average value of the values obtained for each generating point. This makes it possible to select vertices even when the river width or the like is not input or registered in advance.

In this embodiment, in addition to the selection based on the conditions described in FIG. 5, the following condition 3 is further added to select the vertex.
(Condition 3) The length of the folding line obtained by the degeneration process is not less than a predetermined length;
The predetermined length can be arbitrarily set. In the present embodiment, it is set between the polygonal line in the area A1 and the polygonal lines in the areas A2 and A3 in the drawing. That is, in this embodiment, the vertices in the area A1 are selected as the target of the degeneration process, and the vertices in the areas A2 and A3 are excluded. By using Condition 3, it is possible to avoid complicated shapes due to the generation of many unnecessary short line segments due to degeneration. Condition 3 may be set based on the number of vertices included in the broken line, in addition to being set based on the length of the broken line.

  Depending on the polygonal line, there may be a case where the length of the polygonal line does not satisfy the condition 3 due to the presence of about one or two vertices that are removed from the reduction processing target in the condition 1 or 2. In order to avoid such a broken line being deviated from the target of the degeneration process, the following process may be performed. First, the presence / absence of a broken line group in which the number of vertices dropped between broken lines is equal to or less than a predetermined value (for example, about 2) is detected. When such a line group is found, the predetermined value of Condition 2 is increased stepwise for the line group, and it is determined whether or not the line is continuous. If the polygonal line becomes continuous by increasing the predetermined value of condition 2 within a predetermined range, whether or not the dropped vertex is selected as a degeneration target and condition 3 is satisfied based on the continuous polygonal line Determine whether. Even if the predetermined value of condition 2 is increased within a predetermined range, if the broken line is not continuous, it is determined whether or not condition 3 is satisfied in the initial broken line. By performing this process, it is possible to reduce the number of vertices that are excluded from the degeneration target due to minor inadequacy, and it is possible to optimize the generation of outline polygons. Needless to say, conditions 2 and 3 may be used, and the above-mentioned broken line group may be continued unconditionally.

  FIG. 6 is an explanatory diagram showing a result of generating a schematic polygon. Only the area A shown in FIG. 5 is subjected to the reduction process, and the detailed polygon shape is maintained in the other portions. From the detail polygon, the constituent points in the Voronoi polygon including the vertex selected at the time of the reduction process are deleted. As described above, according to the deformation process described in the embodiment, a rough polygon can be generated without causing an irregular shape even for a polygon having a wide portion and a narrow portion such as a river. it can. By setting the predetermined value of condition 2 and the predetermined length of condition 3 shown in the above process, it is possible to generate a schematic polygon corresponding to multiple levels.

C. Preprocessing:
FIG. 7 is a flowchart of a deformation process as a modification. In the first embodiment, an example is shown in which vertices to be reduced are automatically selected from river polygons. In the modification, an example is shown in which the operator specifies a region to be deformed as preprocessing.

  When the processing is started, the CPU displays a map on the screen and inputs the designation of the processing target polygon (step S10A). The display screen DISP is shown in the figure. A polygon RV with hatching in the center of the figure represents a river. The operator can designate an area of the frame Z as a processing target on the display screen DISP with a pointing device such as a mouse. The map data generation device recognizes a range in the frame Z in the river polygon RV as a processing target.

  Next, based on the river polygon RV, the CPU generates a deformed virtual polygon composed of the designated area (step S11A). That is, the range within the frame Z in the river polygon RV is cut out as a virtual polygon.

  For the virtual polygon set in this way, the CPU executes the processing after step S20 of the deformation processing (see FIG. 3) of the embodiment. That is, each process of generating a mother point, Voronoi division, vertex selection, degeneration processing, and smoothing by resampling is performed. In this process, as in the embodiment, vertices to be degenerated are selected based on conditions 1 to 3.

  In the modification, the operator can specify an area to be processed prior to the reduction process. By this process, it is possible to exclude an area that seems to be unnecessary for the degeneration process. Therefore, it is possible to reduce the load of deformation processing for generating a schematic polygon.

  In the modification, the case where the vertex is selected under the same conditions as in the embodiment is illustrated. In the modified example, the vertex extraction process (step 40 in FIG. 3) may be omitted because the operator designates a region to be processed.

D. Post-processing:
FIG. 8 is a flowchart of the deformation correction process. This is post-processing for correcting the general polygon after the deformation processing (see FIGS. 3 and 7) is performed.

  When the process is started, the CPU reads the map data before and after the deformation process and displays both of them in a superimposed manner (step S100). A display example is shown in the figure. The hatched area shows the river polygon. For convenience of explanation, the state in which the reduction process is performed on all the regions A1 to A3 in FIG. 5 is illustrated.

  When the operator designates a required reduction location and a reduction unnecessary location on the display screen, the map data generation device accepts the designation (step S110). In the example in the figure, for example, when the operator determines that the line CL1 obtained by the reduction process is not sufficient, the area Za following the line segment CL1 is designated as a required reduction point. On the other hand, for a portion that is determined not to be reduced, a region surrounding a line segment obtained as a reduction result, such as regions Zb and Zc, is designated.

  Upon receiving these designations, the CPU executes a deformation process for the designated location (step S120). For example, the deformation process is performed again on the area Za. At this time, in order to avoid obtaining the same result as the previous processing, for example, the predetermined value and the predetermined length used in the conditions 1 to 3 when extracting the vertices are gradually reduced, or any one of them It is preferable to take measures such as deleting the condition. In addition to this process, the CPU executes a process for returning to the previous polygon for the area designated as the degeneration unnecessary portion.

  The CPU repeatedly executes the above processing until the operator designates termination (step S130). By performing this processing, it is possible to generate a schematic polygon in a form more in line with the operator's intention.

E. Variations:
FIG. 9 is an explanatory view showing deformation processing as a modification. The process with respect to the river polygon used by FIGS. 4-6 is illustrated. In the deformation process of the modified example, as in the embodiment, the vertex of the Voronoi division (white circle in the figure) is selected, and the constituent point in the Voronoi polygon including this vertex is selected. These constituent points are divided into those to be deleted and those to be left. In the example shown in the figure, the constituent point located on the right side of the line connecting the selected vertices (white circles in the figure) (the constituent point in the region B1) is selected to be left, and the left constituent point should be deleted. It was kimono. In the deforming process, a polygonal line L1 is defined by connecting the remaining constituent points with line segments, and a part of the river polygon is linearized. This process is called a line differentiation process.

  According to the line differentiation process of the modified example, line differentiation can be realized by a simple method. Also, as shown in FIG. 9, by selecting the constituent points that have defined the sides of the river polygon, line differentiation is performed in a form that leaves some of the sides. Since the line segment obtained in this way is sufficiently smooth, there is an advantage that smoothing by resampling (see step S60 in FIG. 3) can be omitted. The line differentiation process according to the modification and the reduction process according to the embodiment may be used in combination. For example, the line differentiation process and the reduction process according to the embodiment may be used depending on the width of the region selected as the target of the deformation process.

  Another aspect of the deformation process is shown in a region B2 in the figure. In the embodiment, when selecting a vertex to be processed, the condition “(Condition 1) a point existing inside a polygon” is considered. In the modification, this condition is removed and the vertex is selected. As a result, as shown in the region B2, there is a possibility that the constituent points that form the concave portions of the river polygon are also selected as processing targets. In the modified example, the constituent point thus selected is deleted. As a result, as shown by the line segment L2 in the figure, it is possible to obtain a simple polygon having a simple shape with the concave portion taken into the river polygon. In this process, the portion that was originally land was expressed as a river, and therefore it may be preferable to avoid the execution of the process when there is a feature in this area. Therefore, it is good also as an aspect which takes an operator's confirmation when performing this process.

  As mentioned above, although the various Example of this invention was described, it cannot be overemphasized that this invention is not limited to these Examples, and can take a various structure in the range which does not deviate from the meaning. In the above example, the processing of river polygons is illustrated, but the present embodiment can be applied to processing of various polygons. For example, when displaying a map by color-coding with contour lines, it may be applied to the deformation of the polygon corresponding to each contour line. Moreover, you may apply to deformations, such as a coastline.

It is explanatory drawing which shows schematic structure of the map data generation apparatus 10 as an Example. It is explanatory drawing which shows the deformation process example of a river polygon. It is a flowchart of a deformation process. It is explanatory drawing which shows the example of a process of Voronoi division | segmentation. It is explanatory drawing which shows the selection method and result of the vertex used as the object of a deformation | transformation process. It is explanatory drawing which shows the production | generation result of a rough polygon. It is a flowchart of deformation processing as a modification. It is a flowchart of a deformation correction process. It is explanatory drawing which shows the deformation process as a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Map data generation apparatus 11 ... Command input part 12 ... Voronoi division part 13 ... Display control part 14 ... Deformation correction part 15 ... Deformation process part 16 ... Map DB reference part 20 ... Map DB

Claims (3)

A map data generation device for generating a schematic polygon for displaying a schematic shape for a wide area map from a detailed polygon prepared for an enlarged map and capable of displaying a detailed shape of a terrain,
A data input unit for inputting the detailed polygon;
A generating point setting unit for setting a generating point of Voronoi division from a component point that forms the detailed polygon and a generation point that is generated on a side of the detailed polygon under a predetermined condition;
A Voronoi dividing unit for dividing the detailed polygon into Voronoi based on the generating point;
Based on the distance from the vertex to the mother point obtained by the Voronoi division, a component point selection unit that selects a component point to be subjected to a deformation process to be performed next among the component points of the detailed polygon,
A map data generation device comprising: a deformation processing unit that deletes at least a part of the selected constituent points and deforms the detailed polygon to generate the general polygon. The map data generation device according to claim 1,
The deformation processing unit is a map data generation device that executes a line segmentation process for expressing at least a part of the detailed polygon with a polygonal line by using the remaining constituent points from which a part of the selected constituent points is deleted. . A map data generation method for generating a schematic polygon for displaying a schematic shape for a wide-area map from a detailed polygon prepared for an enlarged map and capable of displaying a detailed shape of a terrain,
As a process executed by the computer,
A data input step for inputting the detailed polygon;
A generating point setting step for setting a generating point of a Voronoi division from a component point forming the detailed polygon and a generation point generated on a side of the detailed polygon under a predetermined condition;
A Voronoi dividing step for Voronoi dividing the detailed polygon based on the generating point;
Based on the distance from the vertex to the mother point obtained by the Voronoi division, a component point selection step of selecting a component point to be subjected to a deformation process to be performed next among the component points of the detailed polygon;
A map data generation method comprising: a deformation process step of generating a rough polygon by executing a deformation process of deforming the detailed polygon by deleting at least a part of the selected constituent points.