Land surface three-dimensional model generation device, land surface three-dimensional model generation method, and land surface three-dimensional model generation program

Abstract

To allow for reduction in computational complexity and computation time for generation of a three-dimensional model of a land surface.SOLUTION: A computer 11 comprises a central processing unit 12 which generates a three-dimensional model of a land surface on the basis of a three-dimensional point cloud representing a shape of the land surface. The central processing unit 12 performs point cloud segmentation processing, box processing, and model generation processing in this order. In the point cloud segmentation processing, a two-dimensional plane in a three-dimensional coordinate system where individual points of the three-dimensional point cloud are plotted is segmented into a grid to form many subdivided areas. In the box processing, minimum rectangular parallelepipeds surrounding all of points included in the subdivided areas are obtained. In the model generation processing, a three-dimensional model of the land surface is generated by combining the rectangular parallelepipeds of the subdivided areas on the basis of 8 points located at corners of each of the rectangular parallelepipeds in the subdivided areas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a three-dimensional model creation device for the earth's surface, a three-dimensional model creation method for the earth's surface, and a three-dimensional model creation program for the earth's surface. [Background technology]

[0002] When determining a travel path, such as a flight path for an autonomous aerial vehicle such as a drone or a driving path for a self-driving vehicle, a three-dimensional model of the Earth's surface that conforms to the actual shape of the Earth's surface is created, and the travel path is determined by referring to the three-dimensional model. For example, the travel path is determined by referring to the three-dimensional model of the Earth's surface so that the autonomous aerial vehicle or the self-driving vehicle does not come into contact with obstacles on the Earth's surface. A three-dimensional point cloud representing the shape of the Earth's surface is used to create the three-dimensional model of the Earth's surface. Such three-dimensional point cloud data can be obtained by laser surveying or from images of the Earth's surface, as shown in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7123366 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because the amount of data in the three-dimensional point cloud representing the Earth's surface is enormous, creating a three-dimensional model of the Earth's surface based on that data requires a huge amount of calculation and time to create the three-dimensional model. [Means for solving the problem]

[0005] The means for solving the above problems and their effects will be described below. A 3D model creation device for the earth's surface that solves the above-mentioned problems includes a control unit that creates a 3D model of the earth's surface based on a 3D point cloud that represents the shape of the earth's surface. The control unit sequentially executes point cloud partitioning processing, box processing, and model creation processing. The point cloud partitioning processing forms a number of subdivision areas by partitioning a two-dimensional plane in a three-dimensional coordinate system on which each point of the 3D point cloud is plotted into a grid. The box processing finds a solid with the smallest polygonal shape that encloses all of the points included in the number of subdivision areas. The model creation processing creates a 3D model of the earth's surface by connecting the solids of the number of subdivision areas to each other based on multiple points located at the corners of the solids in the number of subdivision areas.

[0006] According to the above configuration, a 3D model of the Earth's surface is created by combining polygonal cylindrical solids in multiple subdivision areas based on a plurality of points in the 3D point cloud representing the shape of the Earth's surface that correspond to the corners of those solids. This reduces the number of points required to create the 3D model of the Earth's surface. As a result, the amount and time of calculation required to create the 3D model of the Earth's surface can be kept small.

[0007] In the above-mentioned 3D model creation device for the earth's surface, the box processing is to find a feature point located at the center between a plurality of points forming the upper surface of the solid, based on the plurality of points. Furthermore, the model creation processing is to provide the created 3D model of the earth's surface with position information of the feature point in a number of subdivided areas.

[0008] The three-dimensional model is provided with position information of the feature points, i.e., position information of obstacles. According to the above configuration, in the three-dimensional model of the earth's surface, the feature points in the many subdivided areas represent the positions of obstacles on the earth's surface. Therefore, when determining a movement path for an autonomous air vehicle, self-driving vehicle, etc., by referring to the three-dimensional model, the movement path can be determined so as to avoid obstacles.

[0009] A method for creating a three-dimensional model of the earth's surface that solves the above-mentioned problems creates a three-dimensional model of the earth's surface based on a three-dimensional point cloud that represents the shape of the earth's surface. This method includes the following first, second, and third steps. In the first step, a number of subdivision areas are formed by dividing a two-dimensional plane in a three-dimensional coordinate system, on which each point of the three-dimensional point cloud is plotted, into a grid pattern. In the second step, the smallest polygonal cylindrical solid that encloses all of the points included in the number of subdivision areas is determined. In the third step, a three-dimensional model of the earth's surface is created by connecting the solids of the number of subdivision areas to each other based on multiple points located at the corners of the solids in the number of subdivision areas.

[0010] According to the above method, a 3D model of the Earth's surface is created by combining solids based on a plurality of points in a 3D point cloud representing the shape of the Earth's surface that correspond to the corners of the solids in a number of subdivided areas. This reduces the number of points used to create the 3D model of the Earth's surface. As a result, the amount and time of calculation required to create the 3D model of the Earth's surface can be reduced.

[0011] In the method for creating a three-dimensional model of the earth's surface, a second step is to determine a feature point located at the center of a plurality of points forming the top surface of the solid, and a third step is to assign position information of the feature point in a number of subdivided areas to the created three-dimensional model of the earth's surface.

[0012] In the three-dimensional model of the Earth's surface, the feature points in the multiple subdivision areas represent the positions of obstacles on the Earth's surface. According to the method, the three-dimensional model is provided with position information of the feature points, i.e., position information of the obstacles. Therefore, when determining a travel path for an autonomous air vehicle or self-driving vehicle by referring to the three-dimensional model, the travel path can be determined so as to avoid the obstacles.

[0013] A 3D model creation program for the Earth's surface that solves the above-mentioned problem causes a computer to sequentially execute a point cloud partitioning process, a box processing process, and a model creation process as processes for creating a 3D model of the Earth's surface based on a 3D point cloud that represents the shape of the Earth's surface. The point cloud partitioning process forms a number of subdivision areas by partitioning a two-dimensional plane in a three-dimensional coordinate system, on which each point of the 3D point cloud is plotted, into a grid pattern. The box processing finds the smallest polygonal cylindrical solid that encloses all of the points included in the number of subdivision areas. The model creation process creates a 3D model of the Earth's surface by connecting the solids of the number of subdivision areas to each other based on multiple points located at the corners of the solids in the number of subdivision areas.

[0014] According to the above program, a 3D model of the Earth's surface is created by combining solids based on a plurality of points in a 3D point cloud representing the shape of the Earth's surface that correspond to the corners of the solids in many subdivided areas. This reduces the number of points required to create the 3D model of the Earth's surface. As a result, the amount and time of calculation required to create the 3D model of the Earth's surface can be reduced.

[0015] In the above-mentioned 3D model creation program for the earth's surface, the box processing is to find a feature point located at the center between a plurality of points that form the upper surface of the solid, and the model creation processing is to provide the created 3D model of the earth's surface with position information of the feature point in a number of subdivided areas.

[0016] The 3D model is provided with position information of the feature points, i.e., position information of obstacles. According to the program, in the 3D model of the Earth's surface, the feature points in the multiple subdivided areas represent the positions of obstacles on the Earth's surface. Therefore, when determining a travel path for an autonomous air vehicle, self-driving vehicle, etc., by referring to the 3D model, the travel path can be determined so as to avoid obstacles. [Brief explanation of the drawings]

[0017] [Figure 1]1 is a schematic diagram showing the configuration of a computer. [Figure 2] 2 is a flowchart showing the execution procedure of a three-dimensional model creation program executed by the computer of FIG. 1. [Figure 3] FIG. 2 is an explanatory diagram showing a two-dimensional plane of a three-dimensional coordinate system on which a three-dimensional point cloud is plotted. [Figure 4] FIG. 4 is a perspective view showing points and rectangular parallelepipeds in the subdivision area on the two-dimensional plane of FIG. 3. [Figure 5] FIG. 4 is a perspective view showing the shape of the earth's surface represented by the rectangular parallelepiped of FIG. 3. [Figure 6] FIG. 5 is a perspective view showing a three-dimensional model of the earth's surface formed by connecting the rectangular parallelepipeds of FIG. 4 together. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of a three-dimensional earth's surface model creating device, a three-dimensional earth's surface model creating method, and a three-dimensional earth's surface model creating program will be described with reference to FIGS. The computer 11 shown in Fig. 1 functions as a three-dimensional model creation device that creates a three-dimensional model of the earth's surface. Trees, buildings, and other objects exist on the earth's surface. The three-dimensional model represents the shape of the earth's surface including the trees, buildings, and other objects. The computer 11 includes a central processing unit 12, a memory unit 13, and a communication unit 14.

[0019] The central processing unit 12 controls various devices in the computer 11, such as the memory unit 13 and communication unit 14, and performs arithmetic processing based on various data. The central processing unit 12 serves as a control unit that creates a three-dimensional model of the earth's surface based on a three-dimensional point cloud that represents the topography of the earth's surface. The memory unit 13 stores various data. The communication unit 14 exchanges data with the outside of the computer 11.

[0020] 1 executes a three-dimensional model creation program for creating a three-dimensional model of the earth's surface. This three-dimensional model creation program causes the computer 11 to execute point cloud partition processing, box processing, and model creation processing in order, thereby creating a three-dimensional model of the earth's surface based on the three-dimensional point cloud representing the earth's surface.

[0021] The flowchart in Figure 2 shows the execution procedure of the program for creating a three-dimensional model of the Earth's surface. In step 101 (S101) of the flowchart, the central processing unit 12 acquires three-dimensional point cloud data representing the Earth's surface, specifically, the three-dimensional coordinates of each point in the three-dimensional point cloud. The three-dimensional point cloud data can be acquired by laser surveying the Earth's surface using an aircraft such as a drone or helicopter. However, the three-dimensional point cloud data can also be acquired by other methods, such as using image data.

[0022] Such three-dimensional point cloud data may be stored in advance in the memory unit 13 of the computer 11. In this case, the central processing unit 12 retrieves the three-dimensional point cloud data from the memory unit 13. The central processing unit 12 may also retrieve the three-dimensional point cloud data directly from the aircraft via the communication unit 14. The three-dimensional point cloud data may also be stored in a server or the like. In this case, the central processing unit 12 may retrieve the three-dimensional point cloud data stored in the server via a network connection via the communication unit 14.

[0023] The process of S102, the process of S103, and the process of S104 in the above flowchart correspond to the point cloud partition process, the box process, and the model creation process, respectively. These processes will be individually described in detail below.

[0024] <Point Cloud Boundary Processing> In the point cloud partitioning process of S102, the central processing unit 12 plots each point in the three-dimensional point cloud in a three-dimensional coordinate system based on the captured three-dimensional point cloud data. This three-dimensional coordinate system has an X-axis, a Y-axis, and a Z-axis. Furthermore, the central processing unit 12 partitions the two-dimensional plane of the three-dimensional coordinate system shown in FIG. 3, i.e., the two-dimensional plane consisting of the X-axis and the Y-axis, into a grid pattern, thereby forming a number of subdivided areas 15 on the two-dimensional plane.

[0025] <Box processing> As the box processing in S103, the central processing unit 12 determines the smallest polygonal prism-shaped solid that encloses all of the points included in the multiple subdivided areas 15. More specifically, a quadrilateral prism-shaped solid, in other words, a rectangular parallelepiped 16, is determined as the solid. Figure 4 shows the rectangular parallelepiped 16 thus determined. Note that the solid determined here does not necessarily have to be a rectangular parallelepiped, and may be, for example, a triangular prism-shaped solid, a hexagonal prism-shaped solid, or an octagonal prism-shaped solid.

[0026] The central processing unit 12 determines the three-dimensional coordinates of each of the multiple points, specifically eight points, that form the corners of the rectangular parallelepiped 16, and then determines the rectangular parallelepiped 16 by connecting these eight points. The rectangular parallelepiped 16 determined here represents the overall outline of a tree or the like protruding above the ground. Figure 5 shows the shape of the earth's surface represented by the rectangular parallelepiped 16 based on each point in the three-dimensional point cloud. Furthermore, the central processing unit 12 determines a feature point 17 located at the center between the four points, specifically four points, that form the top surface of the rectangular parallelepiped 16 shown in Figure 4, based on the three-dimensional coordinates of each of the multiple points, specifically four points. The feature point 17 determined here represents the position of a tree or the like protruding above the ground.

[0027] <Model creation process> In the model creation process of S104, the central processing unit 12 creates a three-dimensional model of the earth's surface as shown in FIG. 6 by connecting the rectangular parallelepipeds 16 of the multiple subdivided areas 15 based on eight points located at the corners of the rectangular parallelepipeds 16 in the multiple subdivided areas 15. Alpha Shapes, for example, may be used to connect the rectangular parallelepipeds 16. Instead of Alpha Shapes, ball pivoting or the like may also be used to connect the rectangular parallelepipeds 16. The central processing unit 12 also assigns position information of feature points 17 in the multiple subdivided areas 15 to the three-dimensional model of the earth's surface created as described above. The feature points 17 represent the positions of trees, buildings, and the like that protrude above the ground. The position information of the feature points 17 here refers to the latitude and longitude of the trees, buildings, and the like.

[0028] Next, a method for creating a three-dimensional model of the earth's surface using a three-dimensional model creation device and a three-dimensional model creation program will be described. In this three-dimensional model creation method, a first step corresponding to the point cloud partition process of S102 in FIG. 2, a second step corresponding to the box process of S103, and a third step corresponding to the model creation process of S104 are performed in this order.

[0029] More specifically, in the first step, based on the data of a three-dimensional point cloud representing the Earth's surface, each point in the three-dimensional point cloud is plotted in a three-dimensional coordinate system consisting of an X-axis, a Y-axis, and a Z-axis. Furthermore, by dividing a two-dimensional plane consisting of the X-axis and the Y-axis in the three-dimensional coordinate system into a grid, a large number of subdivided areas 15 are formed on the two-dimensional plane.

[0030] In the second step, the smallest polygonal cylindrical solid that encloses all of the points included in the multiple subdivided areas 15, i.e., a rectangular parallelepiped 16, is determined. More specifically, the three-dimensional coordinates of each of the multiple points that form the corners of the rectangular parallelepiped 16, i.e., eight points, are determined, and the rectangular parallelepiped 16 that connects these eight points is determined. Furthermore, based on the three-dimensional coordinates of each of the multiple points that form the top surface of the rectangular parallelepiped 16, i.e., four points, a feature point 17 located in the center between these four points is determined.

[0031] In the third step, a three-dimensional model of the earth's surface is created by connecting the rectangular parallelepipeds 16 of the many subdivided areas 15 to each other based on the eight points located at the corners of the rectangular parallelepipeds 16 in the many subdivided areas 15. In addition, position information of the feature points 17 in the many subdivided areas 15, i.e., the latitude and longitude of the feature points 17, is assigned to the three-dimensional model of the earth's surface created as described above.

[0032] According to the present embodiment described above in detail, the following advantageous effects can be obtained. (1) Of the points in the three-dimensional point cloud representing the shape of the Earth's surface, eight points corresponding to the corners of the rectangular parallelepipeds 16 in the many subdivided areas 15 are selected, and the rectangular parallelepipeds 16 are joined to create a three-dimensional model of the Earth's surface. This reduces the number of points used to create the three-dimensional model of the Earth's surface. As a result, the amount and time of calculation required to create the three-dimensional model of the Earth's surface can be kept small.

[0033] (2) The three-dimensional model is provided with position information of feature points 17 for each of the many subdivided areas 15. In this three-dimensional model, the feature points 17 in the many subdivided areas 15 represent the positions of trees, buildings, and the like on the ground. Therefore, when determining a travel route for an autonomous air vehicle, self-driving vehicle, or the like by referring to the three-dimensional model, the travel route can be determined so as to avoid obstacles such as trees and buildings.

[0034] (3) In the point cloud partitioning process, when a two-dimensional plane is partitioned into a grid to form a large number of subdivided areas 15, the computational complexity, computation time, and accuracy required to create a three-dimensional model of the Earth's surface can be adjusted arbitrarily by making the partitions finer or coarser. That is, by making the partitions finer, the accuracy of the created three-dimensional model can be increased. On the other hand, by making the partitions coarser, the computational complexity and computation time required to create the three-dimensional model can be reduced. Therefore, by appropriately adjusting the fineness of the partitions, it is possible to achieve both the accuracy of the created three-dimensional model and the computational complexity and computation time.

[0035] The above embodiment can be modified as follows, for example. It is not necessary to add the position information of the feature points 17 to the three-dimensional model of the earth's surface that is created.

[0036] Although alpha shapes and ball pivoting have been given as examples of methods for connecting the rectangular parallelepipeds 16 of the multiple subdivided areas 15 to each other, other methods can also be used. [Explanation of symbols]

[0037] 11...Computer 12...Central processing unit 13...Storage section 14…Communications Department 15...Subdivision area 16...rectangular prism 17...Feature points

Claims

1. a control unit that creates a three-dimensional model of the earth's surface based on a three-dimensional point cloud that represents the shape of the earth's surface; the control unit sequentially executes a point cloud partition process, a box process, and a model creation process; the point cloud partitioning process forms a number of subdivided areas by partitioning a two-dimensional plane in a three-dimensional coordinate system on which each point of the three-dimensional point cloud is plotted, into a grid pattern; The box processing is to obtain the smallest polygonal cylindrical solid that encloses all of the points included in the multiple subdivided areas, The model creation process creates the three-dimensional model of the earth's surface by connecting the solids of the multiple subdivided areas to each other based on multiple points located at the corners of the solids in the multiple subdivided areas.

2. The box processing involves determining a feature point located at the center between a plurality of points forming the top surface of the solid, and 2. The device for creating a three-dimensional model of the earth's surface according to claim 1, wherein the model creation process adds position information of the feature points in a large number of the subdivided areas to the created three-dimensional model of the earth's surface.

3. A method for creating a three-dimensional model of the earth's surface based on a three-dimensional point cloud representing the shape of the earth's surface, comprising: a first step of dividing a two-dimensional plane in a three-dimensional coordinate system on which each point of the three-dimensional point cloud is plotted into a grid pattern to form a large number of subdivided areas; a second step of determining the smallest polygonal cylindrical solid that encloses all of the points included in the multiple subdivided areas; a third step of creating the three-dimensional model of the Earth's surface by connecting the solids of the multiple subdivision areas to each other based on a plurality of points located at corners of the solids in the multiple subdivision areas; A method for creating a three-dimensional model of the earth's surface.

4. In the second step, a feature point located at the center between a plurality of points forming the top surface of the solid is obtained based on the plurality of points; 4. The method for creating a three-dimensional model of the earth's surface according to claim 3, wherein in the third step, position information of the feature points in a large number of the subdivided areas is added to the created three-dimensional model of the earth's surface.

5. As a process for creating a three-dimensional model of the earth's surface based on the three-dimensional point cloud representing the shape of the earth's surface, a computer is caused to execute a point cloud partition process, a box process, and a model creation process in this order; the point cloud partitioning process forms a number of subdivided areas by partitioning a two-dimensional plane in a three-dimensional coordinate system on which each point of the three-dimensional point cloud is plotted, into a grid pattern; The box processing is to obtain the smallest polygonal cylindrical solid that encloses all of the points included in the multiple subdivided areas, A three-dimensional model creation program for the earth's surface, in which the model creation process creates the three-dimensional model of the earth's surface by connecting the solids of a number of the subdivided areas to each other based on multiple points located at the corners of the solids in a number of the subdivided areas.

6. The box processing involves determining a feature point located at the center between a plurality of points forming the top surface of the solid, and 6. The three-dimensional model creation program for the earth's surface according to claim 5, wherein the model creation process adds position information of the feature points in a large number of the subdivided areas to the created three-dimensional model of the earth's surface.

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