A method and system for making a county-level slope map

Abstract

The present invention discloses a method and system for making a county-level slope map, comprising the following steps: obtaining elevation grid data of a target county and multiple adjacent counties, and performing slope classification processing on the elevation grid data to obtain multiple corresponding slope classification maps, wherein one slope classification map corresponds to one county; performing spot fusion processing on multiple slope classification maps in turn according to a boundary non-fusion strategy, and then performing a verification operation on the fused slope classification map to obtain multiple first fused slope maps containing unfused small faces at the county level; merging multiple first fused slope maps, and performing spot fusion processing and verification operations on the merged fused slope map according to a boundary fusion strategy to obtain a second fused slope map fused with the county boundary. The method and system of the present application can efficiently produce a county-level slope map with high accuracy and meeting the requirements by adopting the methods of slope classification processing, spot fusion processing, and verification, thereby improving production efficiency and accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of geographic information surface landform representation, and in particular to a method and system for producing a county-level slope map. Background Art

[0002] As an important basic data and result of the national land survey, the slope classification map (slope map for short) is an important indicator for ascertaining the quantity, quality and spatial distribution of cultivated land and basic farmland. It is also widely used in geological analysis fields such as forest planning and utilization management, hydrological model establishment, soil erosion analysis, soil and water loss monitoring, early warning monitoring of geological disasters such as landslides, landform simulation, and ecological environment research.

[0003] In the existing technology, slope map generation is mainly completed through the general functions of commonly used GIS software. However, due to the differences between the general functions of GIS software and the requirements of relevant specifications, especially the special processing requirements in the specifications, the slope map generated by the general functions of GIS software has problems such as difficulty in processing large-scale data, slow processing speed, difficulty in achieving personalized processing, incorrect processing results, and difficulty in self-error detection. These problems are in urgent need of improvement and resolution. At the same time, the reality of localization of GIS software also forces us to conduct exploration, research and improvement. Summary of the invention

[0004] In order to solve the technical problems existing in the background technology, the present invention proposes a method and system for producing a county-level slope map.

[0005] The present invention provides a method for producing a county-level slope map, comprising the following steps: S1. Obtaining elevation grid data of a target county and multiple adjacent counties, and performing slope classification processing on the elevation grid data to obtain multiple corresponding slope classification maps, wherein one slope classification map corresponds to one county; S2, after fusing the multiple slope classification maps in turn according to the boundary non-fusion strategy, the fused slope classification maps are verified to obtain multiple first fused slope maps containing boundary non-fused small areas at the county level; S3, merging the multiple first fused slope maps, and performing a patch fusion process and a verification operation on the merged fused slope map according to a boundary fusion strategy to obtain a second fused slope map fused with county boundaries; S4, cutting the second fused slope map according to the target county boundary to obtain a third fused slope map; S5. Obtain generation data format requirements, convert the third fused slope map according to the generation data format requirements, and then output it.

[0006] Preferably, a slope classification map corresponds to a plurality of slope level patches; a slope level patch corresponds to a slope level, and the slope levels are divided into slope level 1, slope level 2, slope level 3, slope level 4 and slope level 5; the boundary non-fusion strategy specifically includes: In the same county, multiple first-type slope-level spots whose area is smaller than a preset area are selected from multiple slope-level spots; Analyze multiple first-type slope level patches one by one; When the slope level corresponding to the first type of slope level patch is equal to the slope level corresponding to the adjacent slope level patch, the first type of slope level patch is merged with the adjacent slope level patch in the same county to obtain the second type of slope level patch; Traversing a plurality of first-type slope level spots according to a second-type slope level spot generation process to generate a plurality of second-type slope level spots; Repeat the above fusion process for multiple second-type slope level spots until the spots corresponding to the obtained multiple third-type slope level spots have areas greater than or equal to the preset area; The slope map composed of multiple third-type slope level patches is used as the first fused slope map.

[0007] Preferably, the boundary fusion strategy specifically includes: Sorting the plurality of third-type slope level spots in the plurality of first fused slope maps according to a preset sorting strategy to obtain a plurality of sorted third-type slope level spots; The sorted third-type slope level patches are sequentially used as fused small faces, and a plurality of adjacent faces of the fused small faces are obtained; Select a fusion large surface from multiple adjacent surfaces, and fuse the fusion small surfaces to the fusion large surface; Repeat the above sorting and merging operations until the areas of all fused large faces exceed the minimum area limited by the fusion.

[0008] Preferably, the preset sorting strategy specifically includes: Sort multiple third-type slope level spots in the order of small to large spot areas; When there are two third-type slope level patches with equal area, the two third-type slope level patches are sorted in ascending order according to the slope levels they correspond to.

[0009] Preferably, the selecting a fused large surface from a plurality of adjacent surfaces specifically includes: Sort multiple adjacent faces according to their slope levels from large to small, and use the adjacent face with the highest ranking as the fused large face; When there are two or more adjacent surfaces with the same slope level, the adjacent surface with the smallest area is taken as the fused large surface.

[0010] Preferably, the verification operation specifically includes: When the verification operation is performed in step S2, the first fused slope map is checked for errors in the merging process; When there is an error in the merging process, restore the wrongly fused second type slope level patch or third type slope level patch to the first type slope level patch or second type slope level patch before fusion, and repeat step S2 until the generated first fused slope map has no merging error after inspection; When the verification operation is performed in step S3, the second fused slope map is checked for errors in the merging process; When there is an error in the merging process, the erroneously fused second type slope level patch or third type slope level patch is restored to the first type slope level patch or second type slope level patch before fusion, and step S3 is repeated until the generated second fused slope map is checked for no merging error.

[0011] Preferably, the error in the merging process is specifically that there is an unfused patch whose area is smaller than a preset area and whose slope level is inconsistent with that of adjacent patches.

[0012] Preferably, the generated data format requirements include but are not limited to the slope classification raster file format and the slope classification file vector format; step S5 specifically includes: When the data format requirement is specifically a slope classification raster file format, the third fused slope map is cut into a grid range according to a standard map sheet, or the initial elevation grid data range is restored, the slope level of each grid point is analyzed to obtain a slope classification raster file format, and the slope classification raster file format is output; The slope classification file vector format includes but is not limited to DXF text format and general GIS data format; when the generated data format requirement is specifically a slope classification file vector format, the third fused slope map is converted into the slope classification file vector format and then output.

[0013] Preferably, the slope value corresponding to the slope level specifically includes: The slope value corresponding to slope level 1 is less than 2°; the slope value corresponding to slope level 2 is 2° to 6°; the slope value corresponding to slope level 3 is 6° to 15°; the slope value corresponding to slope level 4 is 15° to 25°; the slope value corresponding to slope level 5 is greater than 25°.

[0014] The present invention proposes a system for making a county-level slope map, comprising: A data acquisition module is used to acquire the elevation grid data of the target county and its multiple adjacent counties, and perform slope classification processing on the elevation grid data to obtain multiple corresponding slope classification maps, wherein one slope classification map corresponds to one county; The first processing module is used to perform patch fusion processing on multiple slope classification maps in turn according to the boundary non-fusion strategy, and then perform a verification operation on the fused slope classification maps to obtain multiple first fused slope maps containing boundary non-fused small areas at the county level; The second processing module is used to merge the multiple first fused slope maps, and perform spot fusion processing and verification operations on the merged fused slope map according to the boundary fusion strategy to obtain a second fused slope map fused with county boundaries; A clipping module, used for clipping the second fused slope map according to the target county boundary to obtain a third fused slope map; The output module is used to obtain the generation data format requirement, convert the third fused slope map according to the generation data format requirement, and then output it.

[0015] In the present invention, the proposed method and system for making a county-level slope map include obtaining elevation grid data of a target county and multiple adjacent counties, and performing slope classification processing on the elevation grid data to obtain multiple corresponding slope classification maps; performing spot fusion processing on multiple slope classification maps in turn according to the boundary non-fusion strategy, and then performing verification operation on the fused slope classification map to obtain multiple first fused slope maps containing unfused small faces at the county level; merging multiple first fused slope maps, and performing spot fusion processing and verification operation on the merged fused slope map according to the boundary fusion strategy to obtain a second fused slope map fused with the county boundary; cutting the second fused slope map according to the boundary of the target county to obtain a third fused slope map; obtaining the generation data format requirement, and converting the third fused slope map according to the generation data format requirement and outputting it. By adopting the methods of slope classification processing, spot fusion processing, verification, retrieval and error correction, a county-level slope map with high accuracy and meeting the requirements can be efficiently produced, thereby improving production efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the overall workflow structure of a method for making a county-level slope map proposed by the present invention; Figure 2 A detailed slope level map before fusion corresponding to the slope level map of a method for making a county-level slope map proposed in the present invention; Figure 3 A fused detail slope level map corresponding to a slope level map of a method for making a county-level slope map proposed in the present invention; Figure 4 A schematic diagram of the step-by-step workflow structure of a method for making a county-level slope map proposed in the present invention Figure 1; Figure 5 A schematic diagram of the step-by-step workflow structure of a method for making a county-level slope map proposed in the present invention Figure 2 ; Figure 6 A schematic diagram of the step-by-step workflow structure of a method for making a county-level slope map proposed in the present invention Figure 3 ; Figure 7 A schematic diagram of the step-by-step workflow structure of a method for making a county-level slope map proposed in the present invention Figure 4 ; Figure 8 A schematic diagram of the step-by-step workflow structure of a method for making a county-level slope map proposed in the present invention Figure 5 ; Fig. 9 This is a schematic diagram of the system architecture of a county-level slope map production system proposed by the present invention. DETAILED DESCRIPTION

[0017] Reference Figure 1-9 The present invention proposes a method for making a county-level slope map, comprising the following steps: S1. Obtaining elevation grid data of a target county and multiple adjacent counties, and performing slope classification processing on the elevation grid data to obtain multiple corresponding slope classification maps, wherein one slope classification map corresponds to one county; In this embodiment, if Figure 4 As shown, Figure 4 The specific implementation flow chart of step S1. Read in the elevation grid data to generate the initial minimum spot slope level, read in the array variables (spots, line topology, index, fusion results, fusion process involved...) within the scope of the image map establishment, set the data segment array in a step-by-step descending distribution according to the minimum spot multiple, and include the data segment array that exceeds the memory capacity in the transition database, and take the elevation of each point and the surrounding points according to the slope classification calculation formula required by the specification to calculate the slope level (level 1 to level 5) of the point surface spot. The present invention establishes an array dynamic recovery mechanism, combines with the transition database, enhances the ability to process ultra-large data, and can process huge elevation grid data to generate slope maps. Generate slope level spots from elevation grid data, and each leaf number corresponds to the pixel center position, which saves a lot of retrieval and topological operations. The present invention sets the left leaf of the spot to itself (or points to the merged spot number after merging), and the right leaf points to the adjacent spot, so that it is very convenient to retrieve the adjacency relationship of the spot, which is conducive to the central work of the spot small face merging operation.

[0018] S2. After fusing the multiple slope classification maps in turn according to the boundary non-fusion strategy, the fused slope classification maps are verified to obtain multiple first fused slope maps containing boundary non-fused small areas at the county level.

[0019] In this embodiment, a slope classification map corresponds to multiple slope level spots; a slope level spot corresponds to a slope level, and the slope levels are divided into slope level 1, slope level 2, slope level 3, slope level 4 and slope level 5; Figure 5 As shown, Figure 5 is a specific implementation flow chart of step S2. The boundary non-fusion strategy specifically includes: within the same county, select multiple first-type slope-level spots whose spot areas are smaller than a preset area from multiple slope-level spots; analyze multiple first-type slope-level spots one by one; when the slope level corresponding to the first-type slope-level spot is equal to the slope level corresponding to the adjacent slope-level spot, fuse the first-type slope-level spot with the adjacent slope-level spot in the same county to obtain a second-type slope-level spot; traverse multiple first-type slope-level spots according to the second-type slope-level spot generation process to generate multiple second-type slope-level spots; repeat the above fusion process for multiple second-type slope-level spots until the spots corresponding to the obtained multiple third-type slope-level spots are all greater than or equal to the preset area; and use the slope map composed of multiple third-type slope-level spots as the first fused slope map.

[0020] In this embodiment, the slope values ​​corresponding to the slope levels specifically include: the slope value corresponding to slope level 1 is less than 2°; the slope value corresponding to slope level 2 is 2° to 6°; the slope value corresponding to slope level 3 is 6° to 15°; the slope value corresponding to slope level 4 is 15° to 25°; the slope value corresponding to slope level 5 is greater than 25°.

[0021] In this embodiment, a "boundary non-fusion" mechanism is proposed to solve the boundary connection problem without error. The initial slope map generated by the "boundary non-fusion" strategy for merging within the county to solve the boundary connection error. The initialization of the second round of fusion is performed, the initial fusion data and the boundary line are read in, the relevant elevation grid data is read in to calculate the slope level of the map spots on the boundary line, the vector slope level map spots are generated, and the relevant array variables are established. The "boundary non-fusion" plus secondary fusion is used to solve the boundary connection problem without loss.

[0022] Specifically, adjacent patches with the same slope level are merged to generate a new fused array, and the left and right leaf arrays are assigned. After the merger, the index arrays of each level are sorted in order from small to large according to the area and slope level; in the original small face arrays that are merged, only the index pointing array is retained, and the others are deleted in time. Adjacent patches close to the boundary (slope level is zero or leaf relationship is none) are not fused. After the patches with the same slope level are merged, they are sorted: the program sorts each ladder array separately; the rules for sorting and searching related arrays are: area from small to large, and the same area is sorted from small to large according to the slope level. The purpose is to try to merge small areas with larger slope levels in advance under the main line rule of "lower rather than higher", so as to achieve "gradually lower" and preserve the actual micro or special landforms as much as possible.

[0023] S3. Merge the multiple first fused slope maps, and perform patch fusion processing and verification operations on the merged fused slope map according to the boundary fusion strategy to obtain a second fused slope map fused with county boundaries.

[0024] In this embodiment, if Figure 6 As shown, Figure 6 This is a specific implementation flow chart of step S3. The boundary fusion strategy specifically includes: sorting the multiple third-type slope-level spots in the multiple first fused slope maps according to a preset sorting strategy to obtain a plurality of sorted third-type slope-level spots; using the sorted plurality of third-type slope-level spots as fused small faces in turn to obtain a plurality of adjacent faces of the fused small faces; selecting a fused large face from the plurality of adjacent faces, and merging the fused small face with the fused large face; repeating the above sorting and fusion operations until the areas of all fused large faces exceed the minimum area limited by the fusion.

[0025] In this embodiment, the preset sorting strategy specifically includes: Sort multiple third-type slope level spots in the order of small to large spot areas; When there are two third-type slope level patches with equal area, the two third-type slope level patches are sorted in ascending order according to the slope levels they correspond to.

[0026] In this embodiment, a fused large surface is selected from multiple adjacent surfaces, specifically including: sorting the multiple adjacent surfaces from large to small according to the slope level, and taking the adjacent surface with the first ranking as the fused large surface; when there are two or more adjacent surfaces with the same slope level, taking the adjacent surface with the smallest area as the fused large surface.

[0027] In this embodiment, before each data segment starts to be processed, the relevant arrays in the data segment are sorted; Each time a merge is performed, the program will re-sort the current data segment only when the merging small face, the merging destination large face, and the merging result face are all in the current data segment. For the rest, the program will only record the changes in the area, slope level, left and right leaves and other related data without sorting. The program will sort each data segment once before processing it, which can reduce the sorting operation, save a lot of computer processing time, and greatly increase the processing efficiency of the program. Extract the current small face to be merged and obtain the adjacent faces of the current small face: extract the current small face to be merged from the array processed in the previous sorting process, and point to each adjacent face according to the right leaf in front of the current one; Specifically, the present invention searches and merges the patch with the smallest area at any time, and sorts the patches with the same area in ascending order of slope level as the current small face for fusion operation.

[0028] Specifically, filter the adjacent faces of the current face fusion destination: select the preferred order of the difference in the number of slope levels of each adjacent face for the current face slope level: same>small 1>large 1>small 2>small 3>small 4>large 2>large 3>large 4, and record the current face fusion destination; In this embodiment, when orienting adjacent faces, multiple orientations may be selected. This is because the process of merging small faces is a "snowball" process that gradually increases. When merging, it may happen that the slope level of the adjacent faces has changed due to the previous fusion operation, making all adjacent faces formed in the first stage different, and there is a "same" situation in the programming.

[0029] In this embodiment, a special case is set for "lower rather than higher", that is, "big 1" takes precedence over "small 2". There are two situations. The first is that when the current surface slope level is 3, and there are "big 1" level 4 and "small 2" level 1 in the adjacent surfaces, the adjacent surface of level 4 is given priority. The second is that when the current surface slope level is 4, and there are "big 1" level 5, "small 2" level 2 and "small 3" level 1 in the adjacent surfaces, the adjacent surface of level 5 is given priority. An example in reality is that the slope level of the buffer ditch in the mountainous area is 1, and the slope levels of the ridges on both sides are larger. If there is a small surface with a slope level of 3 adjacent to the gully, and its adjacent surface does not have "small 1" level 2, but has big 1 level 4, then the "big 1" is merged upward to maintain the ridge landform, rather than the "small 2" fusion downward to be melted into a flat land. For the merged adjacent surfaces screened out by the present invention, if there are more than one adjacent surfaces with the same slope level, the one with the smallest area is taken as the merged adjacent surface, so as to form a micro-topography and express the special terrain on the spot.

[0030] In this embodiment, each merge considers the area of ​​the large face to be merged plus the current small face. When the merged area is larger than the data segment where the large face is located, a new storage space is created in the corresponding data segment to migrate the merged data. After the current merge operation is completed, the memory array of the current small face and the large face to be merged before the migration is recovered. The second stage merge operation is repeated until all faces, except those related to the boundary, exceed the minimum area limited by the merge.

[0031] In this embodiment, after each merge, unused memory is promptly recovered, and the relevant arrays are promptly re-sorted when there is a change between the current processing surface and the largest surface of the current data segment, so that each merge can start from the surface with the current smallest area and smallest slope level, ensuring that all merge operations are fast and accurate.

[0032] In this embodiment, the verification operation specifically includes: when the verification operation is performed in step S2, checking whether there is an error in the merging processing on the first fused slope map; when there is an error in the merging processing, restoring the erroneously fused second type slope level patch or third type slope level patch to the first type slope level patch or second type slope level patch before fusion, and repeating step S2 until the generated first fused slope map is checked for no error in the merging processing.

[0033] In this embodiment, the verification operation specifically includes: when the verification operation is performed in step S3, the second fused slope map is checked to see whether there is an error in the merging processing; when there is an error in the merging processing, the erroneously fused second type slope level patch or third type slope level patch is restored to the first type slope level patch or second type slope level patch before fusion, and step S3 is repeated until the generated second fused slope map is checked to see whether there is an error in the merging processing.

[0034] In this embodiment, the error in the merging process is specifically that there is an unfused patch whose area is smaller than a preset area and whose slope level is inconsistent with that of adjacent patches.

[0035] In this embodiment, the errors in the merge process include "there are small faces that are smaller than the minimum limited area and have not been melted away", "the final leaf (original face) of the merged face is not completely consistent with the component small faces (original faces) found by recursion", etc. In this embodiment, when the error spots are re-merged, the erroneous fused large surface is restored to its original surface, the relevant array is sorted, and then the second stage is turned to perform the merging operation; when the errors that occurred are checked again and submitted to manual processing, the errors that are found again are no longer re-overlapped, and the relevant errors are directly written into a file for manual intervention. The present invention performs merging error detection and re-merging operations to ensure the accuracy and reliability of slope map generation.

[0036] S4. Cut the second fused slope map according to the target county boundary to obtain a third fused slope map.

[0037] In this embodiment, a complete third fused slope map of the target county is generated; Figure 7 As shown, Figure 7 is a specific implementation flow chart of step S4. Step S4 specifically includes: The second fused slope map of multiple counties is stitched together with county boundaries; the county boundary vector map of the target county is superimposed; the slope map is cut with the boundary line of the target county; the graphic objects outside the target county are deleted; and finally a complete third fused slope map of the target county is obtained.

[0038] S5. Obtain generation data format requirements, convert the third fused slope map according to the generation data format requirements, and then output it.

[0039] In this embodiment, the data format requirements include but are not limited to the slope classification raster file format and the slope classification file vector format; Figure 8 As shown, Figure 8 is a specific implementation flow chart of step S5. Step S5 specifically includes: When the data format requirement is specifically a slope classification raster file format, the third fused slope map is cut into a grid range according to a standard map sheet, or the initial elevation grid data range is restored, the slope level of each grid point is analyzed to obtain a slope classification raster file format, and the slope classification raster file format is output; The slope classification file vector format includes but is not limited to DXF text format and general GIS data format; when the generated data format requirement is specifically the slope classification file vector format, the third fused slope map is converted into the slope classification file vector format and then output.

[0040] In this embodiment, the final slope level result is written into a slope classification grid file specifically as follows: the grid range is cut according to the standard map, or the initial elevation grid data range is restored, the slope level of each grid point is extracted, and written into a standard slope level grid data file; or the result is written into a vector format slope classification file: all the results are written into a text file in a format such as DXF, or a national standard file in a data exchange format, or a general GIS data format SHAPE file, etc. The present invention can break the dependence on the GIS platform and perform the slope classification map generation operation completely independently.

[0041] Reference Figure 1-9 The present invention proposes a system for making a county-level slope map, comprising: A data acquisition module is used to acquire the elevation grid data of the target county and its multiple adjacent counties, and perform slope classification processing on the elevation grid data to obtain multiple corresponding slope classification maps, wherein one slope classification map corresponds to one county; The first processing module is used to perform patch fusion processing on multiple slope classification maps in turn according to the boundary non-fusion strategy, and then perform a verification operation on the fused slope classification maps to obtain multiple first fused slope maps containing boundary non-fused small areas at the county level; The second processing module is used to merge the multiple first fused slope maps, and perform spot fusion processing and verification operations on the merged fused slope map according to the boundary fusion strategy to obtain a second fused slope map fused with county boundaries; A clipping module, used for clipping the second fused slope map according to the target county boundary to obtain a third fused slope map; The output module is used to obtain the generation data format requirement, convert the third fused slope map according to the generation data format requirement, and then output it.

[0042] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for making a county-level slope map, characterized in that: The following steps are involved: S1. Obtaining elevation grid data of a target county and multiple adjacent counties, and performing slope classification processing on the elevation grid data to obtain multiple corresponding slope classification maps, wherein one slope classification map corresponds to one county; S2, after fusing the multiple slope classification maps in turn according to the boundary non-fusion strategy, the fused slope classification maps are verified to obtain multiple first fused slope maps containing boundary non-fused small areas at the county level; S3, merging the multiple first fused slope maps, and performing a patch fusion process and a verification operation on the merged fused slope map according to a boundary fusion strategy to obtain a second fused slope map fused with county boundaries; S4, cutting the second fused slope map according to the target county boundary to obtain a third fused slope map; S5. Obtain generation data format requirements, convert the third fused slope map according to the generation data format requirements, and then output it.

2. The method for making a county-level slope map according to claim 1, characterized in that: A slope classification map corresponds to multiple slope level patches; a slope level patch corresponds to a slope level, and the slope levels are divided into slope level 1, slope level 2, slope level 3, slope level 4 and slope level 5; the boundary non-melting strategy specifically includes: In the same county, multiple first-type slope-level spots whose area is smaller than a preset area are selected from multiple slope-level spots; Analyze multiple first-type slope level patches one by one; When the slope level corresponding to the first type of slope level patch is equal to the slope level corresponding to the adjacent slope level patch, the first type of slope level patch is merged with the adjacent slope level patch in the same county to obtain the second type of slope level patch; Traversing a plurality of first-type slope level spots according to a second-type slope level spot generation process to generate a plurality of second-type slope level spots; Repeat the above fusion process for multiple second-type slope level spots until the spots corresponding to the obtained multiple third-type slope level spots have areas greater than or equal to the preset area; The slope map composed of multiple third-type slope level patches is used as the first fused slope map.

3. The method for making a county-level slope map according to claim 2, characterized in that: The boundary fusion strategy specifically includes: Sorting the plurality of third-type slope level spots in the plurality of first fused slope maps according to a preset sorting strategy to obtain a plurality of sorted third-type slope level spots; The sorted third-type slope level patches are sequentially used as fused small faces, and a plurality of adjacent faces of the fused small faces are obtained; Select a fusion large surface from multiple adjacent surfaces, and fuse the fusion small surfaces to the fusion large surface; Repeat the above sorting and merging operations until the areas of all fused large faces exceed the minimum area limited by the fusion.

4. The method for making a county-level slope map according to claim 3, characterized in that: The preset sorting strategy specifically includes: Sort multiple third-type slope level spots in the order of small to large spot areas; When there are two third-type slope level patches with equal area, the two third-type slope level patches are sorted in ascending order according to the slope levels they correspond to.

5. The method for making a county-level slope map according to claim 4, characterized in that: The step of selecting a fused large surface from a plurality of adjacent surfaces specifically includes: Sort multiple adjacent faces according to their slope levels from large to small, and use the adjacent face with the highest ranking as the fused large face; When there are two or more adjacent surfaces with the same slope level, the adjacent surface with the smallest area is taken as the fused large surface.

6. The method for making a county-level slope map according to claim 4, characterized in that: The verification operation specifically includes: When the verification operation is performed in step S2, the first fused slope map is checked for errors in the merging process; When there is an error in the merging process, restore the wrongly fused second type slope level patch or third type slope level patch to the first type slope level patch or second type slope level patch before fusion, and repeat step S2 until the generated first fused slope map has no merging error after inspection; When the verification operation is performed in step S3, the second fused slope map is checked for errors in the merging process; When there is an error in the merging process, the erroneously fused second type slope level patch or third type slope level patch is restored to the first type slope level patch or second type slope level patch before fusion, and step S3 is repeated until the generated second fused slope map is checked for no merging error.

7. The method for making a county-level slope map according to claim 6, characterized in that: The error in the merging process is specifically that there is an unfused patch whose area is smaller than a preset area and whose slope level is inconsistent with that of adjacent patches.

8. The method for making a county-level slope map according to claim 1, characterized in that: The generated data format requirements include but are not limited to the slope classification raster file format and the slope classification file vector format; step S5 specifically includes: When the data format requirement is specifically a slope classification raster file format, the third fused slope map is cut into a grid range according to a standard map sheet, or the initial elevation grid data range is restored, the slope level of each grid point is analyzed to obtain a slope classification raster file format, and the slope classification raster file format is output; The slope classification file vector format includes but is not limited to DXF text format and general GIS data format; when the generated data format requirement is specifically a slope classification file vector format, the third fused slope map is converted into the slope classification file vector format and then output.

9. The method for making a county-level slope map according to claim 2, characterized in that: The slope values ​​corresponding to the slope levels specifically include: The slope value corresponding to slope level 1 is less than 2°; the slope value corresponding to slope level 2 is 2° to 6°; the slope value corresponding to slope level 3 is 6° to 15°; the slope value corresponding to slope level 4 is 15° to 25°; the slope value corresponding to slope level 5 is greater than 25°.

10. A county-level slope map production system, characterized in that: include: A data acquisition module is used to acquire the elevation grid data of the target county and its multiple adjacent counties, and perform slope classification processing on the elevation grid data to obtain multiple corresponding slope classification maps, wherein one slope classification map corresponds to one county; The first processing module is used to perform patch fusion processing on multiple slope classification maps in turn according to the boundary non-fusion strategy, and then perform a verification operation on the fused slope classification maps to obtain multiple first fused slope maps containing boundary non-fused small areas at the county level; The second processing module is used to merge the multiple first fused slope maps, and perform spot fusion processing and verification operations on the merged fused slope map according to the boundary fusion strategy to obtain a second fused slope map fused with county boundaries; A clipping module, used for clipping the second fused slope map according to the target county boundary to obtain a third fused slope map; The output module is used to obtain the generation data format requirement, convert the third fused slope map according to the generation data format requirement, and then output it.

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