Polygonal Earth Observation Target Representation Method and System Based on Global Discrete Grid

Abstract

This invention relates to the field of satellite Earth observation technology, specifically to a method for representing polygonal Earth observation targets based on a global discrete grid. The method includes the following steps: S1, establishing a grid coverage template library, which includes grid coverage templates corresponding to circular targets of arbitrary radius and grid level; S2, simplifying the boundary of the polygonal Earth observation target to obtain a polygonal region, and calculating the minimum coverage circle of the polygonal region; S3, determining the latitude and longitude and grid level of the center point of the minimum coverage circle; S4, calling an appropriate grid coverage template to cover the polygonal region; S5, cutting off the uncovered portion of the polygonal region covered by the grid coverage template; S6, restoring the cut fragmented grid to a complete grid, obtaining a set of grid cells covering the polygonal Earth observation target. This invention simplifies the grid coverage process by using templates, improves information processing efficiency, and better meets practical application needs.

Description

Technical Field

[0001] This invention relates to the field of satellite Earth observation technology, specifically to a method and system for representing polygonal Earth observation targets based on a global discrete grid. Background Art

[0002] The global discrete grid system is a sphere-based Earth-fitting grid that can be infinitely subdivided without changing its shape. When subdivided to a certain extent, it can simulate the Earth's surface and is expected to fundamentally solve problems such as data fragmentation, geometric deformation, and topological inconsistency in global spatial management and multi-scale operations of planar models. It can provide a continuous and globally unified analysis framework for fields such as remote sensing satellite scheduling and management, UAV flight path planning, and weather forecasting.

[0003] Global discrete grids, as a spatial identification method with a finite number of cells, can effectively solve many challenges faced in fields requiring geographic information analysis. Replacing traditional infinite latitude and longitude coordinates with finite grid coding not only significantly reduces problem complexity but also fully utilizes data resources to meet user needs. Global discrete grids play a crucial role in representing Earth observation targets. Using grid coding to represent the regional extent of targets facilitates subsequent analysis and calculations based on the global discrete grid, improving the efficiency of geographic information processing and ensuring that user response time requirements are met. Especially in large-scale remote sensing constellations covering the Earth, online task allocation is required during multi-satellite collaboration. Traditional latitude and longitude calculations of the payload's field of view and the coverage relationship of the observation area require numerical solutions. However, by uniformly representing the payload's field of view and the observation area using a single geographic grid code, and utilizing the spatial indexing technology of the grid code, the coverage ratio relationship of the payload's field of view and the observation area of ​​different shapes can be quickly determined.

[0004] However, current research lacks specific methods and efficiency improvement techniques for representing Earth observation targets using grids. In particular, polygonal Earth observation targets, including ordinary sector and annular sector, are important target forms in many application fields. Existing methods typically require a large number of latitude and longitude coordinates to describe the target area, which not only increases the complexity of preprocessing but also burdens data storage and transmission. Furthermore, converting grid codes back to regional geometry information is time-consuming due to the sheer number of grid codes. These issues indicate a need for a more efficient method to represent polygonal Earth observation targets, reducing data volume and improving computational efficiency to better meet practical application needs. Summary of the Invention

[0005] This invention provides a method and system for representing polygonal Earth observation targets based on a global discrete grid, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, one aspect of the present invention provides the following technical solution:

[0007] A method for representing polygonal Earth observation targets based on a global discrete grid includes the following steps:

[0008] S1. Establish a grid coverage template library, which includes grid coverage templates corresponding to circular targets of arbitrary radius and arbitrary grid level;

[0009] S2. Simplify the boundary of the polygonal Earth observation target to obtain the polygonal region, and calculate the minimum coverage circle of the polygonal region;

[0010] S3. Determine the latitude and longitude of the center point of the minimum coverage circle and the grid level;

[0011] S4. Invoke the appropriate mesh coverage template to cover the polygonal region;

[0012] S5. Cut off the uncovered portion of the polygonal region by the mesh cover template;

[0013] S6. Restore the broken grid after cutting to a complete grid to obtain a set of grid cells covering the polygonal Earth observation target.

[0014] Preferably, after inputting the radius of the circle and the grid level, the grid cover template library outputs the corresponding grid cover template for use.

[0015] Preferably, the grid hierarchy is used to characterize the size of a grid cell.

[0016] Preferably, step S2 specifically includes:

[0017] Obtain several convex vertices of the polygonal Earth observation target, connect the several convex vertices to obtain the polygonal region, and the polygonal region covers the polygonal Earth observation target.

[0018] Preferably, step S2 further includes:

[0019] The obtained convex vertices are used as a point set P, and the minimum covering circle of the polygonal region is obtained through the Welzl algorithm.

[0020] Preferably, step S4 specifically includes:

[0021] Input the radius of the minimum coverage circle and the preset grid level, call the corresponding grid coverage template from the grid coverage template library, and achieve coverage by aligning the center of the grid coverage template with the center point of the minimum coverage circle.

[0022] Preferably, step S5 specifically includes:

[0023] The grid cover template is cut off according to the boundary of the polygonal region.

[0024] Preferably, step S6 specifically includes:

[0025] In step S5, the grids intersecting the boundary are cut into broken grids, and the broken grids are restored into complete grids to obtain a set of grid cells covering the polygonal Earth observation target.

[0026] Another aspect of the present invention provides a polygonal Earth observation target characterization system based on a global discrete grid, comprising:

[0027] A mesh overlay template library, including mesh overlay templates for circular targets of any radius and any mesh level;

[0028] The graphics simplification module is used to simplify the boundaries of polygonal Earth observation targets to obtain polygonal regions;

[0029] The calculation module calculates the minimum covering circle of the polygonal region;

[0030] Determine the module for the latitude, longitude, and grid level of the center point of the minimum coverage circle;

[0031] The calling module is used to call the adapted mesh coverage template to cover the polygonal region;

[0032] A cut-off module is used to cut off the uncovered portion of the polygonal region by the mesh coverage template.

[0033] The recovery module is used to restore the cut and broken grid to a complete grid, thereby obtaining a set of grid cells covering the Earth observation target.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The method for representing polygonal Earth observation targets based on a global discrete grid provided by this invention establishes a grid coverage template library, which includes grid coverage templates corresponding to circular targets of arbitrary radius and grid level. In the calculation of the grid cell set for polygonal Earth observation targets, the polygonal region covering the target is first obtained by simplifying boundary processing. Then, the minimum coverage circle of the polygonal region is obtained by the Welzl algorithm. The appropriate grid coverage template is called from the grid coverage template library based on the radius of the minimum coverage circle. The polygonal region is covered based on the latitude and longitude of the center point. Then, the uncovered parts of the polygonal region covered by the grid coverage template are removed by boundary cutting. Finally, the broken grids at the boundary intersections are restored to complete grids, thereby obtaining the grid cell set of polygonal Earth observation targets. Compared with the prior art, the representation method for polygonal Earth observation targets provided by this invention is more efficient. The grid coverage process is simplified by calling templates, which improves information processing efficiency and can better meet the needs of practical applications. Attached Figure Description

[0036] Figure 1 A flowchart of the polygon Earth observation target characterization method based on a global discrete grid provided by the present invention;

[0037] Figure 2 A schematic diagram illustrating the simplified boundary processing of polygonal Earth observation targets provided by this invention;

[0038] Figure 3 This is a schematic diagram illustrating the method for obtaining the minimum covering circle of a polygonal region according to the present invention.

[0039] Figure 4 Here is a concrete example of the Welzl algorithm;

[0040] Figure 5 This is a schematic diagram of the grid overlay template for polygonal regions provided by the present invention after overlay.

[0041] Figure 6 This is a schematic diagram of the mesh overlay template for polygonal regions after being cut off, as provided by the present invention.

[0042] Figure 7 This is a schematic diagram of the restored broken mesh of the fan ring provided by the present invention. Detailed Implementation

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] Figure 1 This is a flowchart of a polygon Earth observation target characterization method based on a global discrete grid. Embodiments of this invention provide a polygon Earth observation target characterization method based on a global discrete grid, such as... Figure 1 As shown, the following steps are included:

[0045] S1. Establish a grid coverage template library, which includes grid coverage templates corresponding to circular targets of arbitrary radius and arbitrary grid level;

[0046] S2. Simplify the boundary of the polygonal Earth observation target to obtain the polygonal region, and calculate the minimum coverage circle of the polygonal region;

[0047] S3. Determine the latitude and longitude of the center point of the minimum coverage circle and the grid level;

[0048] S4. Invoke the appropriate mesh coverage template to cover the polygonal region;

[0049] S5. Cut off the uncovered portion of the polygonal region by the mesh cover template;

[0050] S6. Restore the broken grid after cutting to a complete grid to obtain a set of grid cells covering the polygonal Earth observation target.

[0051] Mesh cell coverage for circular targets is readily achievable in this field. Building upon this, this invention establishes a mesh coverage template library for circular targets with arbitrary radii and mesh levels. For polygonal Earth observation targets, it first obtains the polygonal region covering the target by simplifying boundary processing. Then, it obtains the minimum coverage circle of the polygonal region using the Welzl algorithm. Finally, by calling the mesh coverage template, cutting, and restoring the fragmented mesh, it can more quickly obtain the set of mesh cells covering the polygonal Earth observation target. Compared to the existing method of mesh filling based on the center of the Earth observation target, this invention only needs to obtain the radius of the minimum coverage circle corresponding to the polygonal Earth observation target and the latitude and longitude of the center point to quickly achieve mesh coverage. The method of calling the template simplifies the mesh coverage process and improves information processing efficiency.

[0052] In an embodiment of the present invention, the mesh overlay template library outputs a corresponding mesh overlay template for use after inputting the radius of the circle and the mesh level.

[0053] In an embodiment of the present invention, specifically, the grid hierarchy is used to characterize the size of a grid cell.

[0054] Figure 2This is a schematic diagram illustrating the simplified boundary processing of polygonal Earth observation targets provided by the present invention. Figure 2 As shown, in an embodiment of the present invention, step S2 specifically includes:

[0055] Obtain several convex vertices of the polygonal Earth observation target, connect the several convex vertices to obtain the polygonal region, and the polygonal region covers the polygonal Earth observation target.

[0056] The obtained convex vertex should be the vertex with the greatest convexity of the polygonal Earth observation target, so as to ensure that the polygonal region covers the polygonal Earth observation target.

[0057] Figure 3 This is a schematic diagram illustrating how the minimum covering circle of a polygonal region is obtained, as provided by the present invention. Figure 3 As shown, in an embodiment of the present invention, step S2 specifically includes:

[0058] The obtained convex vertices are used as a point set P, and the minimum covering circle of the polygonal region is obtained through the Welzl algorithm.

[0059] In a plane, the minimum covering circle is the circle with the smallest radius that can completely cover a set of points or a planar figure. In this invention, the minimum covering circle is the circle with the smallest radius that covers a polygonal region.

[0060] Figure 4 This is a concrete example of the Welzl algorithm. The core idea of ​​the Welzl algorithm is to recursively process the point set to gradually construct the minimum covering circle. The algorithm starts with an empty set R and gradually adds points from the point set P. After each addition, it checks whether the point is inside or on the boundary of the current minimum covering circle; if the point is outside, the minimum covering circle needs to be updated until all points in the point set P are included.

[0061] Figure 5 This is a schematic diagram showing the grid overlay template for polygonal regions provided by the present invention after overlay. Figure 5 As shown, in an embodiment of the present invention, step S4 specifically includes:

[0062] Input the radius of the minimum coverage circle and the preset grid level, call the corresponding grid coverage template from the grid coverage template library, and achieve coverage by aligning the center of the grid coverage template with the center point of the minimum coverage circle.

[0063] Figure 6 This is a schematic diagram showing the result of cutting off a mesh overlay template for a polygonal region, as provided by the present invention. Further, as... Figure 6 As shown, in an embodiment of the present invention, step S5 specifically includes:

[0064] The grid cover template is cut off according to the boundary of the polygonal region.

[0065] Through the above steps, the mesh overlay template is quickly cut off according to the boundary of the polygonal region, thereby achieving initial coverage of the polygonal region.

[0066] Figure 7 This is a schematic diagram illustrating the restoration of a broken mesh in a polygonal region, as provided by the present invention. Furthermore, as... Figure 7 As shown, in an embodiment of the present invention, step S5 specifically includes:

[0067] In step S5, the grids intersecting the boundary are cut into broken grids, and the broken grids are restored into complete grids to obtain a set of grid cells covering the polygonal Earth observation target.

[0068] In scenarios with arbitrary radius and arbitrary grid level, it is almost impossible for the grid in the grid overlay template to align with the boundary of the polygonal region. Therefore, after cutting, the grids that intersect with the boundary will inevitably be cut into broken grids. These broken grids affect the integrity of the grid overlay. Therefore, by restoring these broken grids into complete grids, the set of grid cells covering the polygonal Earth observation target can be obtained.

[0069] It should be noted that the appendix to this invention specification... Figures 2 to 7 The sector in the figure can be a polygonal region on a sphere that is not projected onto the global discrete grid system, or it can be a polygonal region projected onto the sphere of the global discrete grid system. The attached figure is only for the purpose of understanding and does not necessarily mean that the processing is done on a plane. It can also be done on a sphere.

[0070] Embodiments of the present invention also provide a polygon Earth observation target characterization system based on a global discrete grid, comprising:

[0071] A mesh overlay template library, including mesh overlay templates for circular targets of any radius and any mesh level;

[0072] The graphics simplification module is used to simplify the boundaries of polygonal Earth observation targets to obtain polygonal regions;

[0073] The calculation module calculates the minimum covering circle of the polygonal region;

[0074] Determine the module for the latitude, longitude, and grid level of the center point of the minimum coverage circle;

[0075] The calling module is used to call the adapted mesh coverage template to cover the polygonal region;

[0076] A cut-off module is used to cut off the uncovered portion of the polygonal region by the mesh coverage template.

[0077] The recovery module is used to restore the cut and broken grid to a complete grid, thereby obtaining a set of grid cells covering the Earth observation target.

[0078] This invention establishes a grid coverage template library. In calculating the grid cell set for polygonal Earth observation targets, it first obtains the polygonal region covering the target by simplifying boundary processing. Then, it obtains the minimum coverage circle of the polygonal region using the Welzl algorithm. Using the radius of the minimum coverage circle, it calls a suitable grid coverage template from the template library and covers the polygonal region based on the latitude and longitude of the center point. Next, it removes the uncovered portions of the polygonal region by cutting off the grid coverage template at the boundary. Finally, it restores the broken grids at boundary intersections to a complete grid, thereby obtaining the grid cell set of the Earth observation target. Compared to existing technologies, the representation method for polygonal Earth observation targets provided by this invention is more efficient. By using template coverage, it simplifies the grid coverage process, improves information processing efficiency, and better meets practical application needs.

[0079] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for representing polygonal Earth observation targets based on a global discrete grid, characterized in that, Includes the following steps: S1. Establish a grid coverage template library, which includes grid coverage templates corresponding to circular targets of arbitrary radius and arbitrary grid level; S2. Simplify the boundary of the polygonal Earth observation target to obtain the polygonal region, and calculate the minimum coverage circle of the polygonal region; S3. Determine the latitude and longitude of the center point of the minimum coverage circle and the grid level; S4. Invoke the appropriate mesh coverage template to cover the polygonal region; S5. Cut off the uncovered portion of the polygonal region by the mesh coverage template; S6. Restore the broken mesh after cutting to a complete mesh to obtain a set of mesh cells covering the polygonal Earth observation target; Step S4 specifically includes: Input the radius of the minimum coverage circle and the preset grid level, call the corresponding grid coverage template from the grid coverage template library, and achieve coverage by aligning the center of the grid coverage template with the center point of the minimum coverage circle; Step S5 specifically includes: The mesh covering template is cut off according to the boundary of the polygonal region; Step S6 specifically includes: In step S5, the grids intersecting the boundary are cut into broken grids, and the broken grids are restored into complete grids to obtain a set of grid cells covering the polygonal Earth observation target.

2. The polygon Earth observation target characterization method based on a global discrete grid according to claim 1, characterized in that, The grid overlay template library outputs the corresponding grid overlay template for use after inputting the radius of the circle and the grid level.

3. The polygon Earth observation target characterization method based on a global discrete grid according to claim 2, characterized in that, The grid hierarchy is used to characterize the size of a grid cell.

4. The polygon Earth observation target characterization method based on a global discrete grid according to claim 3, characterized in that, Step S2 specifically includes: Obtain several convex vertices of the polygonal Earth observation target, connect the several convex vertices to obtain the polygonal region, and the polygonal region covers the polygonal Earth observation target.

5. The polygon Earth observation target characterization method based on a global discrete grid according to claim 4, characterized in that, Step S2 also includes: The obtained convex vertices are taken as a point set P, and the minimum covering circle of the polygonal region is obtained by Welzl algorithm.

6. A polygonal Earth observation target characterization system based on a global discrete grid, characterized in that, include: A mesh overlay template library, including mesh overlay templates for circular targets of any radius and any mesh level; The graphics simplification module is used to simplify the boundaries of polygonal Earth observation targets to obtain polygonal regions; The calculation module calculates the minimum covering circle of the polygonal region; Determine the module for the latitude, longitude, and grid level of the center point of the minimum coverage circle; The module is used to call an adapted mesh coverage template to cover the polygonal region; the radius of the minimum coverage circle and the preset mesh level are input, and the corresponding mesh coverage template is called from the mesh coverage template library. Coverage is achieved by aligning the center of the mesh coverage template with the center point of the minimum coverage circle. The cutting module is used to cut off the uncovered portion of the polygonal region by the mesh coverage template; and to cut off the mesh coverage template according to the boundary of the polygonal region. The recovery module is used to restore the cut and fragmented grid to a complete grid, thereby obtaining a set of grid cells covering the Earth observation target. The grid intersecting the boundary is cut into broken grids, and the broken grids are restored into complete grids to obtain a set of grid cells covering the polygonal Earth observation target.

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