A terrain slicing method and system based on irregular triangulated mesh generation

Abstract

The present invention provides a terrain slicing method and system based on irregular triangulated mesh partitioning. The method comprises: receiving a terrain file to be sliced; based on a predetermined target projection mode, calculating the total number of tiles and tile indexes, and creating multiple tile subtasks; executing the multiple tile subtasks in parallel, partitioning the terrain file, and generating multiple triangulated mesh tiles; and generating the meta information of the triangulated mesh tiles according to the tile indexes. The present invention combines irregular triangulated mesh partitioning with map slicing, greatly reducing the tile storage space and the amount of data transmitted by tile data, and can support faster terrain rendering and smaller rendering memory consumption.

Description

Technical Field

[0001] The invention relates to the technical field of remote sensing image processing, and in particular to a terrain slicing method and system based on irregular triangulated grid partitioning. Background Art

[0002] Terrain tiles are an optimization strategy to improve the user experience of map browsing. They are terrain slice files within a certain map range and contain a series of scales. Terrain tiles follow a pyramid structure, and each tile can be uniquely identified by level, row and column number. With the development of digital earth technology, more and more people view terrain maps in a three-dimensional way. In order to allow users to browse the terrain at a faster speed, the global terrain will be divided into quadtree grids. The traditional terrain tile segmentation method uses a regular grid height map method. Grid (i.e. GRID) DEM is difficult to express the sudden change of complex terrain without changing the grid size. In places with flat terrain, there is a large amount of data redundancy, resulting in higher data transmission bandwidth requirements. When rendering the terrain visualization platform created based on the regular grid, the redundant grid will reduce rendering performance and increase memory consumption. As map applications become more and more widespread, the market has put forward new requirements for map application technology to improve the user experience of browsing maps with smaller data transmission and more sophisticated terrain data expression. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0004] To this end, according to a first aspect of the present invention, a terrain slicing method based on irregular triangulated meshing is provided, comprising:

[0005] Receive the terrain file to be sliced;

[0006] Based on the predetermined target projection method, calculate the total number of tiles and tile index, and create multiple tile subtasks;

[0007] Executing the plurality of tile subtasks in parallel, segmenting the terrain file, and generating a plurality of triangulated mesh tiles;

[0008] Meta information of the triangulated mesh tile is generated according to the tile index.

[0009] Furthermore, after receiving the terrain file to be sliced, it is determined whether the projection mode of the terrain file is consistent with the target projection mode. If not, projection conversion is performed on the terrain file.

[0010] Furthermore, each tile subtask corresponds to one or more tile indexes, and the content of each tile subtask includes:

[0011] According to the corresponding tile index, obtain the corresponding image grid block;

[0012] The image grid blocks are processed according to an irregular triangulated meshing algorithm to generate triangulated mesh tiles.

[0013] Further, the generating the meta information of the triangulated mesh tile according to the tile index includes:

[0014] Calculating the association relationship between the plurality of triangulated mesh tiles according to the tile index;

[0015] The association relationship and the level information, range information, and projection information of the triangulated mesh tile are stored as meta-information of the triangulated mesh tile.

[0016] According to a second aspect of the present invention, there is provided a terrain slicing system based on irregular triangulated meshing, comprising:

[0017] A receiving module, used for receiving a terrain file to be sliced;

[0018] The task creation module is used to calculate the total number of tiles and tile indexes based on the predetermined target projection mode, and create multiple tile subtasks;

[0019] A tile segmentation module, used to execute the plurality of tile subtasks in parallel, segment the terrain file, and generate a plurality of triangulated mesh tiles;

[0020] An information generation module is used to generate the meta information of the triangulated mesh tile according to the tile index.

[0021] Furthermore, the receiving module also includes a projection conversion module, which is used to determine whether the projection mode of the terrain file is consistent with the target projection mode after receiving the terrain file to be sliced, and if not, perform projection conversion on the terrain file.

[0022] Furthermore, each tile subtask corresponds to one or more tile indexes, and the content of each tile subtask includes:

[0023] According to the corresponding tile index, obtain the corresponding image grid block;

[0024] The image grid blocks are processed according to an irregular triangulated meshing algorithm to generate triangulated mesh tiles.

[0025] Furthermore, the information generation module includes:

[0026] A tile association module, used for calculating the association relationship between the plurality of triangulated mesh tiles according to the tile index;

[0027] The information storage module is used to store the association relationship and the level information, range information, and projection information of the triangulated mesh tile as the meta information of the triangulated mesh tile.

[0028] According to a third aspect of the present invention, there is provided a computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the method described in the first aspect when executing the program.

[0029] According to a fourth aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, wherein when the program is executed by a processor, the method as described in the first aspect is implemented.

[0030] The terrain slicing method and system based on irregular triangulated networks proposed in the present invention combine irregular triangulated network subdivision with map slicing, use sparser triangles to express in areas with flat terrain, and increase the density of triangulated networks in areas with complex terrain. While ensuring the same terrain accuracy, the tile storage space and the amount of data transmitted by tile data are greatly reduced, which can support faster terrain rendering and smaller rendering memory consumption.

[0031] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0033] Figure 1 is a flow chart of a terrain slicing method according to the present invention;

[0034] Figure 2 is a structural diagram of a terrain slicing system according to the present invention. DETAILED DESCRIPTION

[0035] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0036] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0037] Maps are displayed on a plane, and spherical coordinates need to be converted to plane coordinates. This conversion process is called projection. The most common projection is the Mercator projection. It receives input as longitude and latitude of WGS84, but when projecting, the earth is no longer treated as an ellipsoid but as a standard sphere with a radius of 6378137 meters to simplify calculations. After the Web Mercator projection, the map becomes a flat map. Considering that sometimes you need to see macroscopic map information (such as the borders of each country in the world map), and sometimes you need to see very microscopic map information (such as road conditions during navigation). For this reason, this map needs to be divided into levels. At the highest level (zoom = 0), the least information is required, and only the most important macro information needs to be retained, so it can be represented by a 256x256 pixel picture; at the next level (zoom = 1), the amount of information becomes more, and it is represented by a 512x512 pixel picture; and so on, the lower the level, the higher the pixels, and the pixels of the next level are 4 times that of the current level. In this way, a pyramid coordinate system is formed from the highest level to the lowest level. For each image, we divide it into 256x256 images, called tiles. In this way, at the highest level (zoom = 0), there is only one tile; at the next level (zoom = 1), there are 4 tiles; at the next level (zoom = 2), there are 16 tiles, and so on.

[0038] refer to Figure 1 , which shows the process of the terrain slicing method based on irregular triangulated network according to the present invention, including:

[0039] S11, receiving a terrain file to be sliced;

[0040] The format of the terrain file is tif or vrt. If it is tfi, multiple tif files need to be merged into one vrt file first.

[0041] After receiving the terrain file to be sliced, optionally, the tile projection, storage and other parameters of the terrain file are checked to determine whether it is a valid terrain file. If not, the process ends; if valid, it is further determined whether the projection mode of the terrain file is consistent with the predetermined target projection mode. If so, it proceeds to step S12; if not, the terrain file is projected and converted, and its projection mode is converted to the target projection mode before proceeding to step S12.

[0042] S12, based on the predetermined target projection mode, calculating the total number of tiles and tile indexes, and creating multiple tile subtasks;

[0043] Each tile subtask corresponds to one or more tile indexes. The number of tile subtasks can be determined according to the total number of tiles and the processing capability of each subtask to achieve higher processing efficiency.

[0044] S13, executing the multiple tile subtasks in parallel, segmenting the terrain file, and generating multiple triangulated mesh tiles;

[0045] Based on the multi-tasking mode, tile subtasks can be decomposed into different threads or processes and executed in parallel, thereby improving the processing speed of terrain slicing.

[0046] The content of each tile subtask includes:

[0047] According to the corresponding tile index, obtain the corresponding image grid block;

[0048] The image grid blocks are processed according to an irregular triangulated meshing algorithm to generate triangulated mesh tiles.

[0049] The irregular triangulated network model is referred to as TIN. It divides the area into a connected triangular network based on a finite set of points in the area. Any point in the area falls on the vertex, edge or inside the triangle of the triangular face. If the point is not on a vertex, the elevation value of the point is usually obtained by linear interpolation (the elevation of the two vertices of the edge is used on the edge, and the elevation of the three vertices is used inside the triangle).

[0050] S14. Generate metadata of the triangulated mesh tile according to the tile index.

[0051] Further, the generating the meta information of the triangulated mesh tile according to the tile index includes:

[0052] Calculating the association relationship between the plurality of triangulated mesh tiles according to the tile index;

[0053] The association relationship and the level information, range information, and projection information of the triangulated mesh tile are stored as meta-information of the triangulated mesh tile, and basic information for publishing is provided to the tile service.

[0054] The present invention combines the principle of irregular triangulation meshing with the principle of tile map, uses terrain grid data, and first obtains the grid tiles corresponding to the tiles according to the quadtree principle of tile map, and then performs triangulation based on the grid tiles by using the irregular triangulation algorithm to generate triangulated terrain tiles, and at the same time establishes the position association relationship between tiles to generate metadata files of tiles. Thus, sparser triangular faces are used to express in areas with flat terrain, and the density of triangulation is increased in areas with complex terrain. Under the condition of ensuring the same terrain accuracy, the tile storage space and the amount of data transmitted by tile data are greatly reduced, which can support faster terrain rendering and smaller rendering memory consumption.

[0055] refer to Figure 2 , which shows the structure of the terrain slicing system based on irregular triangulated network according to the present invention, including:

[0056] A receiving module 21, used for receiving a terrain file to be sliced;

[0057] Furthermore, the receiving module 21 also includes a projection conversion module, which is used to determine whether the projection mode of the terrain file is consistent with the target projection mode after receiving the terrain file to be sliced, and if not, perform projection conversion on the terrain file.

[0058] The task creation module 22 is used to calculate the total amount of tiles and tile indexes based on a predetermined target projection mode, and create multiple tile subtasks. Each tile subtask corresponds to one or more tile indexes, and the content of each tile subtask includes:

[0059] According to the corresponding tile index, obtain the corresponding image grid block;

[0060] The image grid blocks are processed according to an irregular triangulated meshing algorithm to generate triangulated mesh tiles.

[0061] A tile segmentation module 23 is used to execute the plurality of tile subtasks in parallel, segment the terrain file, and generate a plurality of triangulated mesh tiles;

[0062] The information generation module 24 is used to generate the meta information of the triangulated mesh tile according to the tile index.

[0063] Furthermore, the information generating module 24 includes:

[0064] A tile association module, used for calculating the association relationship between the plurality of triangulated mesh tiles according to the tile index;

[0065] The information storage module is used to store the association relationship and the level information, range information, and projection information of the triangulated mesh tile as the meta information of the triangulated mesh tile.

[0066] For the parts not described in detail in the system embodiment, please refer to the relevant description of the method embodiment, which will not be repeated here.

[0067] According to another embodiment of the present invention, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, reference is made to Figure 1 The method described.

[0068] According to another embodiment of the present invention, a computer readable storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, Figure 1 The method described.

[0069] In the several embodiments provided in the present application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0070] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0071] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0072] A person skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing the relevant hardware through a program, and the program can be stored in a computer-readable storage medium. The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For a person skilled in the art, the present invention can have various changes and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A terrain slicing method based on irregular triangulated meshing, characterized in that: include: Receive the terrain file to be sliced; Based on a predetermined target projection mode, the total tile amount and tile index are calculated, and a plurality of tile subtasks are created, wherein the number of the tile subtasks is determined according to the total tile amount and the processing capability of each subtask; wherein each tile subtask corresponds to one or more tile indexes, and the content of each tile subtask includes: According to the corresponding tile index, obtain the corresponding image grid block; Processing the image grid blocks according to an irregular triangulated meshing algorithm to generate triangulated mesh tiles; Executing the plurality of tile subtasks in parallel, segmenting the terrain file, and generating a plurality of triangulated mesh tiles; Meta information of the triangulated mesh tile is generated according to the tile index.

2. The method according to claim 1, characterized in that After receiving the terrain file to be sliced, it is determined whether the projection mode of the terrain file is consistent with the target projection mode. If not, projection conversion is performed on the terrain file.

3. The method according to claim 1, characterized in that The step of generating the meta information of the triangulated mesh tile according to the tile index includes: Calculating the association relationship between the plurality of triangulated mesh tiles according to the tile index; The association relationship and the level information, range information, and projection information of the triangulated mesh tile are stored as meta-information of the triangulated mesh tile.

4. A terrain slicing system based on irregular triangulated meshing, characterized in that: include: A receiving module, used for receiving a terrain file to be sliced; The task creation module is used to calculate the total tile amount and tile index based on the predetermined target projection mode, and create multiple tile subtasks, where the number of the tile subtasks is determined according to the total tile amount and the processing capacity of each subtask; wherein each tile subtask corresponds to one or more tile indexes, and the content of each tile subtask includes: According to the corresponding tile index, obtain the corresponding image grid block; Processing the image grid blocks according to an irregular triangulated meshing algorithm to generate triangulated mesh tiles; A tile segmentation module, used to execute the plurality of tile subtasks in parallel, segment the terrain file, and generate a plurality of triangulated mesh tiles; An information generation module is used to generate the meta information of the triangulated mesh tile according to the tile index.

5. The system according to claim 4, characterized in that The receiving module also includes a projection conversion module, which is used to determine whether the projection mode of the terrain file is consistent with the target projection mode after receiving the terrain file to be sliced, and if not, perform projection conversion on the terrain file.

6. The system according to claim 4, characterized in that The information generation module comprises: A tile association module, used for calculating the association relationship between the plurality of triangulated mesh tiles according to the tile index; The information storage module is used to store the association relationship and the level information, range information, and projection information of the triangulated mesh tile as the meta information of the triangulated mesh tile.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the method according to any one of claims 1 to 3 is implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 3 is implemented.

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