Polygonal earth observation target characterization method and system based on global discrete grid

Abstract

The invention relates to the technical field of satellite earth observation, in particular to a polygonal earth observation target characterization method based on global discrete grids, which comprises the following steps: S1, establishing a grid coverage template library which comprises grid coverage templates corresponding to circular targets with any radius and any grid level; s2, simplifying the boundary of the polygonal earth observation target to obtain a polygonal region, and calculating to obtain a minimum coverage circle of the polygonal region; s3, determining the longitude and latitude and the grid hierarchy of the center point of the minimum coverage circle; s4, calling an adaptive grid coverage template, and covering the polygonal region; s5, cutting off the part, which is not covered by the grid covering template, of the polygonal region; and S6, recovering the cut broken grids into complete grids, and obtaining a grid unit set covering the polygonal earth observation target. According to the method, the grid coverage process is simplified in a mode of calling template coverage, the information processing efficiency is improved, and the actual application requirements can be better met.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite earth observation, and specifically to a method and system for representing earth observation targets of polygons based on a global discrete grid. Background Art

[0002] The global discrete grid system is a spherical-based earth body fitting grid that can be infinitely subdivided without changing its shape. When subdivided to a certain extent, it can achieve the purpose of simulating the earth's surface, and is expected to fundamentally solve problems such as data breaks, geometric deformations, and topological inconsistencies in global space management and multi-scale operations of plane models. It can provide a continuous and globally unified analysis framework for fields such as remote sensing satellite scheduling management, UAV route planning, and meteorological prediction.

[0003] As a spatial identification method with a finite number of elements, the global discrete grid can effectively solve the problems faced in many current fields that require geographical information analysis. Using a finite grid code to replace the traditional infinite longitude and latitude coordinates can not only greatly reduce the complexity of the problem, but also make full use of data resources to meet user needs. The global discrete grid plays an important role in the process of representing earth observation targets. Using grid codes to represent the regional scope of targets is conducive to subsequent analysis and calculation based on the global discrete grid, improving the efficiency of geographical information processing to ensure meeting user requirements in terms of response time. Especially in large-scale remote sensing constellation earth coverage, when multiple satellites cooperate, task allocation needs to be carried out online. Calculating the coverage relationship between the payload field of view and the observation area based on traditional longitude and latitude requires numerical solution. By uniformly representing different payload fields of view and observation areas with a set of geographical grid codes and using the spatial indexing technology of grid codes, the coverage ratio relationship of different shapes of the payload field of view and the observation area can be quickly completed.

[0004] However, there is currently a lack of research on specific methods and efficiency improvement methods for using grids to represent earth observation targets. In particular, earth observation targets of polygons, including ordinary sectors and circular sectors, are important forms of earth observation targets in many application fields. Existing methods usually require inputting a large number of longitude and latitude coordinates to describe the target area, which not only increases the complexity of preprocessing but also leads to a burden in data storage and transmission. In addition, when converting grid codes back to regional geometric information, due to the huge number of grid codes, the reverse calculation takes a long time. These problems indicate that we need a more efficient method to represent earth observation targets of polygons, reduce the data volume, and improve the calculation efficiency to better meet the actual application requirements. Summary of the Invention

[0005] The present invention provides a method and system for representing earth observation targets of polygons based on a global discrete grid to solve the problems raised in the above background art.

[0006] To achieve the above object, one aspect of the present invention provides the following technical solution: A method for representing a polygon ground observation target based on a global discrete grid, comprising the following steps: S1. Establish a grid coverage template library, which includes grid coverage templates corresponding to circular targets with any radius and any grid level; S2. Simplify the boundary of the polygon ground observation target to obtain a polygon area, and calculate the minimum covering circle of the polygon area; S3. Determine the longitude and latitude of the center point of the minimum covering circle and the grid level; S4. Call an adapted grid coverage template to cover the polygon area; S5. Cut off the uncovered part of the grid coverage template for the polygon area; S6. Restore the cut fragmented grids to complete grids to obtain a set of grid cells covering the polygon ground observation target.

[0007] Preferably, after inputting the radius and grid level of the input circle, the grid coverage template library outputs the corresponding grid coverage template for calling.

[0008] Preferably, the grid level is used to represent the size of a grid cell.

[0009] Preferably, step S2 specifically includes: Obtain several convex vertices of the polygon ground observation target, connect the several convex vertices to obtain the polygon area, and the polygon area covers the polygon ground observation target.

[0010] Preferably, step S2 further includes: Take the several convex vertices obtained as a point set P, and obtain the minimum covering circle of the polygon area through the Welzl algorithm.

[0011] Preferably, step S4 specifically includes: Input the radius of the minimum covering circle and a 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 covering circle.

[0012] Preferably, step S5 specifically includes: Cut off the grid coverage template according to the boundary of the polygon area.

[0013] Preferably, step S6 specifically includes: In step S5, the grids intersecting the boundary are cut into broken grids, and the broken grids are restored to complete grids, obtaining a set of grid cells covering the polygon ground observation target.

[0014] Another aspect of the present invention provides a polygon ground observation target characterization system based on a global discrete grid, including: A grid coverage template library, including grid coverage templates corresponding to circular targets with arbitrary radii and arbitrary grid levels; A graphic simplification module for simplifying the boundary of the polygon ground observation target to obtain a polygon area; A calculation module for calculating the minimum covering circle of the polygon area; A determination module for determining the longitude and latitude of the center point of the minimum covering circle and the grid level; A calling module for calling an adapted grid coverage template to cover the polygon area; An excision module for excising the uncovered part of the grid coverage template from the polygon area; A restoration module for restoring the cut broken grids to complete grids, obtaining a set of grid cells covering the ground observation target.

[0015] Compared with the prior art, the beneficial effects of the present invention are: The polygon ground observation target characterization method based on a global discrete grid provided by the present invention establishes a grid coverage template library, which includes grid coverage templates corresponding to circular targets with arbitrary radii and arbitrary grid levels. In the calculation of the set of grid cells of the polygon ground observation target, first, a polygon area covering the polygon ground observation target is obtained through simplified boundary processing, then the minimum covering circle of the polygon area is obtained through the Welzl algorithm, an adapted grid coverage template is called from the grid coverage template library based on the radius of the minimum covering circle, the polygon area is covered based on the longitude and latitude of the center point, then the uncovered part of the grid coverage template from the polygon area is excised through the boundary, and finally, the broken grids intersecting the boundary are restored to complete grids, thereby obtaining a set of grid cells of the polygon ground observation target. Compared with the prior art, the characterization method for polygon ground observation targets provided by the present invention is more efficient. The process of grid coverage is simplified by the method of calling templates for coverage, the information processing efficiency is improved, and the actual application requirements can be better met. Description of the Drawings

[0016] Figure 1 It is a flowchart of the polygon ground observation target characterization method based on a global discrete grid provided by the present invention; Figure 2 It is a schematic diagram of the simplified boundary processing of the polygon ground observation target provided by the present invention; Figure 3 Schematic diagram of obtaining the minimum covering circle of a polygon region provided by the present invention; Figure 4 Specific example of the Welzl algorithm; Figure 5 Schematic diagram after covering a polygon region with a grid covering template provided by the present invention; Figure 6 Schematic diagram after cutting the grid covering template for a polygon region provided by the present invention; Figure 7 Schematic diagram after restoring the broken grid for a fan-shaped ring provided by the present invention. Specific embodiments

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0018] Figure 1 Flowchart of a method for representing polygon ground observation targets based on a global discrete grid. The embodiments of the present invention provide a method for representing polygon ground observation targets based on a global discrete grid, as Figure 1 shown, including the following steps: S1. Establish a grid covering template library, where the grid covering template library includes grid covering templates corresponding to circular targets with arbitrary radii and arbitrary grid levels; S2. Simplify the boundary of the polygon ground observation target to obtain a polygon region, and calculate the minimum covering circle of the polygon region; S3. Determine the longitude, latitude, and grid level of the center point of the minimum covering circle; S4. Call an adapted grid covering template to cover the polygon region; S5. Cut off the uncovered part of the polygon region by the grid covering template; S6. Restore the cut broken grid to a complete grid to obtain a set of grid cells covering the polygon ground observation target.

[0019] The grid cell coverage for circular targets is easily achievable in the art. On this basis, the present invention establishes a grid coverage template library for circular targets with arbitrary radii and arbitrary grid levels. For polygon ground observation targets, first, a polygon area covering the polygon ground observation target is obtained through simplified boundary processing. Then, the minimum covering circle of the polygon area is obtained through the Welzl algorithm. Finally, by calling the grid coverage template, excising, and restoring the broken grids, a set of grid cells covering the polygon ground observation target can be obtained more quickly. Compared with the method of filling and covering grids based on the center of the ground observation target in the prior art, the present invention only needs to obtain the radius of the minimum covering circle corresponding to the polygon ground observation target and the longitude and latitude of the center point, and then the grid coverage can be quickly realized. The process of grid coverage is simplified by calling the template coverage method, improving the information processing efficiency.

[0020] In an embodiment of the present invention, after the radius of the input circle and the grid level are input into the grid coverage template library, the corresponding grid coverage template is output for calling.

[0021] In an embodiment of the present invention, specifically, the grid level is used to characterize the size of a grid cell.

[0022] Figure 2 It is a schematic diagram of the simplified boundary processing of the polygon ground observation target provided by the present invention. As Figure 2 shown, in an embodiment of the present invention, step S2 specifically includes: Obtain several convex vertices of the polygon ground observation target, and connect the several convex vertices to obtain the polygon area, and the polygon area covers the polygon ground observation target.

[0023] The obtained convex vertices should be the vertices with the maximum convexity of the polygon ground observation target, so as to ensure that the polygon area covers the polygon ground observation target.

[0024] Figure 3 It is a schematic diagram of obtaining the minimum covering circle of the polygon area provided by the present invention. As Figure 3 shown, in an embodiment of the present invention, step S2 specifically includes: Take the several obtained convex vertices as the point set P, and obtain the minimum covering circle of the polygon area through the Welzl algorithm.

[0025] On a plane, the minimum covering circle refers to the circle that can completely cover a certain point set or a certain plane figure and has the smallest radius. The minimum covering circle obtained in the present invention is the circle that covers the polygon area and has the smallest radius.

[0026] Figure 4This is a specific example of the Welzl algorithm. The core idea of the Welzl algorithm is to gradually construct the minimum covering circle by recursively processing the point set. The algorithm starts with an empty set R and gradually adds points from the point set P. After adding each point, 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 processed.

[0027] Figure 5 This is a schematic diagram after covering with the grid covering template for the polygon region provided by the present invention. As Figure 5 shown, in the embodiment of the present invention, step S4 specifically includes: Input the radius of the minimum covering circle and the preset grid level, call the corresponding grid covering template from the grid covering template library, and achieve the covering by aligning the center of the grid covering template with the center point of the minimum covering circle.

[0028] Figure 6 This is a schematic diagram after cutting the grid covering template for the polygon region provided by the present invention. Further, as Figure 6 shown, in the embodiment of the present invention, step S5 specifically includes: Cut the grid covering template according to the boundary of the polygon region.

[0029] Through the above steps, quickly cut the grid covering template according to the boundary of the polygon region, so as to achieve the preliminary covering of the polygon region.

[0030] Figure 7 This is a schematic diagram after restoring the broken grids for the polygon region provided by the present invention. Even further, as Figure 7 shown, in the embodiment of the present invention, step S5 specifically includes: The grids intersecting with the boundary in step S5 are cut into broken grids, and the broken grids are restored into complete grids to obtain a set of grid units covering the polygon ground observation target.

[0031] In the scenarios of any radius and any grid level, it is almost impossible for the grids in the grid covering template to align with the boundary of the polygon region. Therefore, after cutting, there will inevitably be grids intersecting with the boundary cut into broken grids, and these broken grids affect the integrity of the grid covering. Therefore, by restoring these broken grids into complete grids, a set of grid units covering the polygon ground observation target can be obtained.

[0032] It should be noted that the attached Figures 2 to 7The sector in it can be a polygonal area on a sphere that is not projected onto the global discrete grid system, or a polygonal area on a sphere projected onto the global discrete grid system. The accompanying drawings are only for easy understanding and do not necessarily mean that the processing is done on a plane. It can also be done on a sphere.

[0033] An embodiment of the present invention also provides a polygon ground observation target characterization system based on a global discrete grid, including: A grid coverage template library, including grid coverage templates corresponding to circular targets with any radius and any grid level; A graphic simplification module for simplifying the boundary of the polygon ground observation target to obtain a polygonal area; A calculation module for calculating the minimum covering circle of the polygonal area; A determination module for determining the longitude and latitude of the center point of the minimum covering circle and the grid level; A calling module for calling an adapted grid coverage template to cover the polygonal area; An excision module for excising the uncovered part of the grid coverage template for the polygonal area; A restoration module for restoring the fragmented grid after cutting into a complete grid to obtain a set of grid cells covering the ground observation target.

[0034] In the present invention, by establishing a grid coverage template library, in the calculation of the set of grid cells for the polygon ground observation target, first, a polygonal area covering the polygon ground observation target is obtained through boundary simplification processing, then the minimum covering circle of the polygonal area is obtained through the Welzl algorithm, an adapted grid coverage template is called from the grid coverage template library based on the radius of the minimum covering circle, the polygonal area is covered based on the longitude and latitude of the center point, then the uncovered part of the grid coverage template for the polygonal area is excised by the boundary, and finally the fragmented grids intersecting at the boundary are restored into a complete grid, thereby obtaining the set of grid cells of the ground observation target. Compared with the prior art, the characterization method for the polygon ground observation target provided by the present invention is more efficient. The grid coverage process is simplified by the way of calling the template for coverage, the information processing efficiency is improved, and the actual application requirements can be better met.

[0035] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for representing polygon ground observation targets based on a global discrete grid, characterized in that It includes the following steps: S1. Establish a grid coverage template library, which includes grid coverage templates corresponding to circular targets with any radius and any grid level; S2. Simplify the boundary of the polygon ground observation target to obtain a polygon area, and calculate the minimum covering circle of the polygon area; S3. Determine the longitude and latitude of the center point of the minimum covering circle and the grid level; S4. Call the adapted grid coverage template to cover the polygon area; S5. Cut off the uncovered part of the polygon area by the grid coverage template; S6. Restore the cut broken grids to complete grids to obtain a set of grid cells covering the polygon ground observation target.

2. The method for representing polygon ground observation targets based on a global discrete grid according to claim 1, wherein After the radius and grid level of the input circle are input into the grid coverage template library, the corresponding grid coverage template is output for calling.

3. The method for representing a polygon ground observation target based on a global discrete grid according to claim 2, wherein The grid level is used to characterize the size of a grid cell.

4. The method for representing a polygon ground observation target based on a global discrete grid according to claim 3, wherein Step S2 specifically includes: Obtain several convex vertices of the polygon ground observation target, connect the several convex vertices to obtain the polygon area, and the polygon area covers the polygon ground observation target.

5. The method for representing polygon ground observation targets based on a global discrete grid according to claim 4, wherein Step S2 also includes: Take the several convex vertices obtained as a point set P, and obtain the minimum covering circle of the polygon area through the Welzl algorithm.

6. The method for representing polygon ground observation targets based on a global discrete grid according to claim 5, wherein Step S4 specifically includes: Input the radius of the minimum covering 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 covering circle.

7. The method for representing polygon ground observation targets based on a global discrete grid according to claim 6, wherein Step S5 specifically includes: Cut off the grid coverage template according to the boundary of the polygon area.

8. The method for representing polygon ground observation targets based on a global discrete grid according to claim 7, characterized in that, Step S6 specifically includes: In step S5, the grids intersecting with the boundary are cut into broken grids, and the broken grids are restored to complete grids to obtain a set of grid cells covering the polygon ground observation target.

9. A polygon ground observation target characterization system based on a global discrete grid, characterized in that, It includes: A grid coverage template library, which includes grid coverage templates corresponding to circular targets with any radius and any grid level; A graphic simplification module, which is used to simplify the boundary of the polygon ground observation target to obtain a polygon area; A calculation module, which calculates the minimum covering circle of the polygon area; A determination module, which is used for the longitude and latitude of the center point of the minimum covering circle and the grid level; A calling module, which is used to call the adapted grid coverage template to cover the polygon area; An excision module, which is used to cut off the uncovered part of the polygon area by the grid coverage template; A restoration module, which is used to restore the cut broken grids to complete grids to obtain a set of grid cells covering the ground observation target grid.

Images