A method and system for judging the relationship between the edges of a U-shaped vector graphic

Abstract

The application relates to the field of geographic spatial data analysis, and provides a U-shaped vector graph edge connection relationship judgment method and system, which comprises a client, a boundary selection module, a layer conversion module, a buffer processing module, a feature module, a segmentation module, an intersection module, a comparison module, a merging module and a result display module. The application accurately captures U-shaped roads and rivers, further analyzes the edge connection consistency of the linear ground objects, solves the problem that the edge connection of the U-shaped roads and rivers is not judged in the prior art, reduces invalid calculation of the system, improves system operation efficiency, sets feature ID and feature code, and makes the surface layer and the line layer still save the initial surface layer data and ground type information after multiple segmentation and merging, so that the checking result can be repeatedly verified, and the accuracy of land survey quality checking is further improved.

Description

Technical Field

[0001] This invention relates to the field of geospatial data analysis, specifically a method and system for determining the edge relationships of U-shaped vector graphics. Background Technology

[0002] The "Rules for Quality Inspection of County-level Database Update Results of Land Survey" stipulates that the quality elements of county-level databases for land change surveys are divided into four categories: validity, completeness, standardization, and consistency. Among them, consistency includes consistency between graphics and attribute values, semantic consistency between layers, topological consistency within layers, and topological consistency between layers.

[0003] Specifically, each vector feature has a corresponding attribute table that records various attribute information of the feature. The location, shape, and interrelationships of vector features on the map need to be associated with the corresponding values ​​in their attribute tables. In addition, the definition and naming rules of attribute fields in each vector layer must be consistent to ensure that the same attribute information is used to describe geographic entities. In the same vector layer, the spatial relationships between features need to conform to the real-world situation and satisfy topological rules and constraints. The spatial relationships between features in different vector layers must also be consistent with the geographic relationships in the real world and satisfy topological rules and constraints.

[0004] Therefore, in the quality inspection of land surveys between two adjacent districts and counties, it is necessary to check whether the land types are consistent, whether there is obvious misalignment of land features, and whether the widths are basically consistent. However, the original vector elements of adjacent districts and counties may be measured and edited by different personnel and organizations, which makes the vector elements at the map boundary susceptible to errors and other factors, making it impossible to align and splice them correctly, thus affecting the quality of land survey results.

[0005] Chinese patent application number 202310391296.3 discloses a method, apparatus, and electronic device for individualizing geographic surveying and mapping sheet vector data. The method includes: inputting the surveying and mapping vector data of each sheet into a knowledge graph in the form of triples; searching for fragmented geographic entities using a spatial query language based on the boundary line triples of each sheet to determine multiple fragmented geographic entities and their corresponding boundary marker triples; searching for neighboring geographic entities in neighboring sheets using a spatial query language based on the boundary marker triples of each fragmented geographic entity and the encoded triples of each sheet to obtain a set of neighboring geographic entities corresponding to each fragmented geographic entity; and obtaining the target geographic entity corresponding to each fragmented geographic entity based on the set of neighboring geographic entities corresponding to each fragmented geographic entity. This invention automatically individualizes geographic surveying and mapping sheet vector data by searching for fragmented geographic entities and neighboring geographic entities using a spatial query language and by merging entities.

[0006] However, the above invention can only solve the problem of splicing between different map sheets, and cannot check the vector elements at the splicing point.

[0007] In existing technologies, some software systems developed for land survey quality inspection can intelligently handle some basic tasks in quality inspection, among which the inspection of vector features at splicing points is mainly based on the following criteria:

[0008] 1. If a polygon borders only one polygon, the boundary is considered consistent; if a polygon borders multiple polygons, the boundary is considered inconsistent.

[0009] 2. If a certain map patch has the same land type as all adjacent map patches, then the land type is determined to be consistent; if a certain map patch has a different land type than any adjacent map patch, then the land type is determined to be inconsistent.

[0010] The above criteria are simple and efficient, but when inspecting U-shaped roads and rivers, especially when the U-shaped patch is divided into two straight patches and one curved patch, the two ends of the curved patch are connected to the two straight patches at the same time. This means that regardless of whether the boundary of the curved patch is consistent, it may be misjudged as having inconsistent boundaries. Moreover, there is no method to solve this problem in the existing technology, which affects the efficiency of the quality inspection of land surveys.

[0011] In summary, this invention provides a method and system for determining the edge relationships of U-shaped vector graphics to solve the above-mentioned problems. Summary of the Invention

[0012] This invention provides a method and system for judging the edge relationships of U-shaped vector graphics. By proposing a method and system that can effectively identify and judge the edge relationships of U-shaped linear features such as roads and rivers, it solves the problem of misjudgment that easily occurs in the vector feature inspection in the prior art.

[0013] The specific technical solution of this invention is as follows:

[0014] A system for determining the edge-joining relationships of a U-shaped vector graphic includes:

[0015] The client is used to load land survey data from two adjacent counties, A and B, visualize the land survey data, and provide an interactive interface;

[0016] The boundary selection module is used to read the map boundary lines, surface layer data and land use information of two adjacent counties A and B in the land survey data, and select the surface layers that the map boundary lines pass through.

[0017] The layer conversion module converts the selected face layer into a line layer based on the selection result of the boundary selection module, and then merges all the line layers. The merged line layer is denoted as line segment L.

[0018] The buffer processing module is used to buffer the line segment L, generate a buffer surface layer, and use the buffer surface layer to clip the surface layer selected by the boundary selection module, retaining the area overlapping with the buffer surface layer, and generating several clipping surface layers.

[0019] The feature module is used to set feature IDs for the clipped surface layer generated by the buffer processing module and save the land cover information of the original surface layer.

[0020] The segmentation module divides the clipping surface layer generated by the buffer processing module along the map sheet boundary line, and then merges the segmented clipping surface layers according to the district / county where they are located. The merged layers are denoted as surface layers PA and PB.

[0021] The intersection module is used to calculate the geometric intersection of line segment L and surface layers PA and PB, extract the intersecting line segments, denoted as intersecting line segments LA and LB, delete the small line segments in intersecting line segments LA and LB, and identify the U-shaped line segments in intersecting line segments LA and LB, denoted as line segments UA and UB.

[0022] The comparison module is used to extract the clipping surface layer adjacent to line segment UA in the surface layer PA, denoted as Ai, and search for the clipping surface layer adjacent to clipping surface layer Ai in the surface layer PB, denoted as Bi. It analyzes the quantitative relationship between clipping surface layers Ai and Bi, compares the feature IDs and land use information of clipping surface layers Ai and Bi, analyzes the boundary and land use edge consistency of clipping surface layer Ai, and outputs the feature code TFMA expressing the boundary and land use edge consistency of clipping surface layer Ai. The comparison module is also used to extract the clipping surface layer adjacent to line segment UB in the surface layer PB, denoted as Bn, and search for the clipping surface layer Bn adjacent to clipping surface layer An in the surface layer PA. It analyzes the quantitative relationship between clipping surface layers Bn and An, compares the feature IDs and land use information of clipping surface layers Bn and An, analyzes the boundary and land use edge consistency of clipping surface layer Bn, and outputs the feature code TFMB expressing the boundary and land use edge consistency of clipping surface layer Bn.

[0023] The merging module is used to search for clipping polygon layers adjacent to clipping polygon layer Ai in polygon layer PB, merge them with clipping polygon layer Ai to form a new clipping polygon layer, denoted as NAi, analyze the boundary and land type edge consistency of clipping polygon layer NAI, and output the feature code TFMNA expressing the boundary and land type edge consistency of clipping polygon layer NAI; the merging module is also used to search for clipping polygon layers adjacent to clipping polygon layer Bn in polygon layer PA, merge them with clipping polygon layer Bn to form a new clipping polygon layer, denoted as NBn, analyze the boundary and land type edge consistency of clipping polygon layer NBn, and output the feature code TFMNB expressing the boundary and land type edge consistency of clipping polygon layer NBn.

[0024] The result display module is used to query the feature codes TFMNA and TFMNB and display the query results.

[0025] In a preferred embodiment, the boundary selection module is used to select the surface layer through which the map sheet boundary line passes from the land survey data, detect the edge of the surface layer, extract the pixel value information of the surface layer, find adjacent pixels with different pixel values, and set the pixel as a candidate edge point. The above operation is repeated until all candidate edge points are determined, and all candidate edge points are connected to form an edge line. The boundary selection module is mainly used to determine the edge line of the surface layer.

[0026] In a preferred embodiment, the layer conversion module is used to separate the edge lines from the surface layers, save the edge lines separately to form line layers, and merge all the line layers; the layer conversion module is mainly used to convert the surface layers into line layers.

[0027] In a preferred embodiment, the buffer processing module is used to set the buffer radius of line segment L and generate a buffer surface layer based on the buffer radius; the buffer processing module is mainly used to generate the buffer surface layer of line segment L.

[0028] In a preferred embodiment, the intersection module uses an intersection function to calculate the line segment L and surface layers PA and PB, extracting the intersecting line segments LA and LB, as shown in the following formula:

[0029] LA = ST_Intersection(L, PA)

[0030] LB=ST_Intersection(L,PB) (1)

[0031] In the formula, ST_Intersection() is the intersection function, L represents line segment L, and PA and PB represent surface layers PA and PB, respectively;

[0032] The intersection module calculates the length of each segment in the intersecting line segments LA and LB using the following formula:

[0033] length=sqrt((x2-x1)^2+(y2-y1)^2) (2)

[0034] In the formula, (x1,y1) and (x2,y2) are the coordinates of the endpoints of the line segment, sqrt() is the square root function, and length is the length;

[0035] The intersection module sets a line segment length threshold and deletes line segments with lengths less than the threshold from the intersecting line segments LA and LB;

[0036] The intersection module calculates the slope of each segment in the intersecting line segments LA and LB using the following formula:

[0037] slope=(y2-y1) / (x2-x1) (3)

[0038] In the formula, (x1,y1) and (x2,y2) are the coordinates of the endpoints of the line segment, and slope is the slope.

[0039] The intersection module checks line segments with slopes close to 0, slopes that do not exist, and slopes that are very large. It analyzes the positional relationship between the starting point, ending point, and intermediate point of the line segment and extracts line segments that meet the characteristics of a U-shaped line segment. The intersection module is mainly used to filter U-shaped line segments.

[0040] In a preferred embodiment, the comparison module is used to query all clipping surface layers adjacent to clipping surface layers Ai and Bn in surface layers PA and PB, and compare the feature ID and land use information of each adjacent clipping surface layer with clipping surface layers Ai and Bn; the comparison module is mainly used to analyze the edge consistency of clipping surface layers Ai and Bn.

[0041] In a preferred embodiment, the merging module is used to query all feature codes TFMA and TFMB to determine the boundary and land use consistency of the clipping surface layers NAi and NBn; the merging module is mainly used for overall analysis of the clipping surface layers NAi and NBn.

[0042] In a preferred embodiment, the result display module is used to query the feature codes TFMNA and TFMNB, search for feature codes whose boundaries and land types are inconsistent, and after a successful search, mark the corresponding clipping surface layers NAi and NBn, highlight the surface layers corresponding to the clipping surface layers NAi and NBn, and display the inconsistency between the boundary of the surface layer and the land type according to the feature codes TFMNA and TFMNB.

[0043] This invention also provides a method for determining the edge-joining relationship of a U-shaped vector graphic, comprising the following steps:

[0044] S1, load land survey data, read map boundary lines, surface layer data and land type information of two adjacent counties A and B, select the surface layer through which the map boundary line passes, convert the surface layer into a line layer, and then merge all the line layers. The merged line layer is denoted as line segment L.

[0045] S2, set a buffer for line segment L, generate a buffer surface layer, use the buffer surface layer to clip the surface layer selected in step S1, retain the area overlapping with the buffer surface layer, generate several clipped surface layers, set a feature ID for each clipped surface layer, and each clipped surface layer saves the land use information of the original surface layer.

[0046] S3, divide the clipping surface layer along the map boundary lines of the two adjacent districts A and B, and then merge the divided clipping surface layers according to the districts and counties they belong to. The merged layers are denoted as surface layers PA and PB.

[0047] S4. Calculate the geometric intersection of line segment L with surface layer PA and surface layer PB respectively, extract the intersecting line segments, and denot them as intersecting line segments LA and LB. Identify the U-shaped line segments in intersecting line segments LA and LB, and denot them as line segments UA and UB.

[0048] S5. Extract the clipping surface layer adjacent to line segment UA in the surface layer PA, denoted as Ai. Search for the clipping surface layer adjacent to clipping surface layer Ai in the surface layer PB, denoted as Bi. Analyze the quantitative relationship between clipping surface layers Ai and Bi. Compare the feature ID and land use information of clipping surface layers Ai and Bi. Analyze the boundary and land use edge connection consistency of clipping surface layer Ai. Output the feature code TFMA that expresses the boundary and land use edge connection consistency of clipping surface layer Ai.

[0049] S6. Search for the clipping surface layer adjacent to clipping surface layer An in the surface layer PB, merge it with clipping surface layer An to form a new clipping surface layer, denoted as NAi, read the feature code TFMA, analyze the boundary and land type edge consistency of clipping surface layer NAI, and output the feature code TFMNA that expresses the boundary and land type edge consistency of clipping surface layer NAI.

[0050] S7. Extract the clipping plane layer adjacent to line segment UB from the plane layer PB, denoted as Bn. Search for the clipping plane layer adjacent to clipping plane layer Bn in the plane layer PA, denoted as An. Analyze the quantitative relationship between clipping plane layer Bn and clipping plane layer An. Compare the feature ID and land use information of clipping plane layer Bn and clipping plane layer An. Analyze the boundary and land use edge connection consistency of clipping plane layer Bn. Output the feature code TFMB that expresses the boundary and land use edge connection consistency of clipping plane layer Bn.

[0051] S8. Search for clipping surface layers adjacent to clipping surface layer Bn in surface layer PA, merge them with clipping surface layer Bn to form a new clipping surface layer, denoted as NBn, read the feature code TFMB, analyze the boundary and land type edge consistency of clipping surface layer NBn, and output the feature code TFMNB that expresses the boundary and land type edge consistency of clipping surface layer NBn.

[0052] S9, query the feature codes TFMNA and TFMNB, find the clipping surface layers NAi and NBn where the boundary and land type are inconsistent, and complete the judgment of the edge relationship of the U-shaped vector graphics.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] 1. This invention accurately captures U-shaped roads and rivers by converting surface layers into line layers and performing intersection calculations on the line layers. It further analyzes the edge consistency of such linear features, solving the problem of lacking edge judgment for U-shaped roads and rivers in the prior art.

[0055] 2. This invention reduces invalid calculations and improves system operating efficiency by setting a minimum line segment length threshold to exclude tiny line segments and filter out intersecting line segments of a certain length.

[0056] 3. By setting feature IDs and feature codes, this invention enables the surface and line layers to retain the initial surface layer data and land use information even after multiple divisions and mergers, thus allowing for repeated verification of inspection results and further improving the accuracy of land survey quality inspection. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0058] Figure 2 This is a schematic diagram of the system structure of the present invention.

[0059] Figure 3 This is a schematic diagram of land survey data according to Embodiment 1 of the present invention.

[0060] Figure 4 This is a schematic diagram of land survey data according to Embodiment 2 of the present invention.

[0061] Figure 5 This is a schematic diagram of land survey data according to Embodiment 3 of the present invention.

[0062] Figure 6 This is a schematic diagram of land survey data according to Embodiment 4 of the present invention. Detailed Implementation

[0063] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0064] Example 1:

[0065] like Figure 1-3 As shown, this embodiment takes the inspection of land survey data of two adjacent districts A and B by land survey quality inspectors as an example; in this embodiment, the boundaries and land categories of the land survey data are consistent.

[0066] First, land survey quality inspectors launch the client based on the U-shaped vector graphic edge relationship judgment system. The client, a desktop application, loads the land survey data and displays it visually.

[0067] Subsequently, based on the judgment system, the land survey quality inspectors used the boundary selection module to read the map boundary lines, surface layer data and land category information of the two adjacent districts A and B from the land survey data.

[0068] Since land survey data is generally stored in the form of map sheets, in this embodiment, the land survey data of two adjacent counties A and B can be regarded as two map sheets composed of several rectangular map sheets. The map sheet boundary lines of the two adjacent counties A and B are represented by a series of interconnected horizontal and vertical lines.

[0069] In this embodiment, the surface layer is represented by patches with the same pixel value. Therefore, in the land survey data of two adjacent counties A and B, patches with the same pixel value are regarded as a surface layer. That is, the surface layer can be composed of patches on both sides of the map boundary line. Land use information is stored in the attribute table of the surface layer.

[0070] Then, based on the judgment system, the land survey quality inspectors use the boundary selection module to select the surface layer that the map sheet boundary line passes through, detect the edge line of the surface layer, and segment the surface layer according to the edge line to separate the surface layer from the original map sheet it belongs to.

[0071] The main workflow for detecting the edge lines of the surface layer is as follows: First, extract the pixel value information of the surface layer. Based on the pixel value of the surface layer, find pixels with different pixel values ​​in any direction and set them as candidate edge points. According to the spatial position and continuity of the candidate edge points, connect all candidate edge points to form an edge line.

[0072] Subsequently, based on the judgment system, the land survey quality inspectors used the layer conversion module to separate the edge lines from the surface layers, saved the edge lines separately to form line layers, and merged all the line layers. The merged line layer is denoted as line segment L.

[0073] Then, based on the judgment system, the land survey quality inspectors used the buffer processing module to set the buffer radius of line segment L to 10m. The buffer radius refers to the area with a radius of 10m around any point in line segment L. The buffers of all points in line segment L are merged, and the merged buffer is filled with a pixel value. After saving, a buffer surface layer is formed. The spatial relationship between each surface layer and the buffer surface layer is judged. For the surface layers that overlap with the buffer surface layer, a clipping operation is performed to retain the area that overlaps with the buffer surface layer. After saving, several clipping surface layers are generated.

[0074] Clipping a surface layer essentially removes the redundant parts of the surface layer, retaining only the area adjacent to the edge line. This helps save system computing power and thus improves system efficiency.

[0075] Next, based on the judgment system, the land survey quality inspectors used the feature module to set feature IDs for several clipping surface layers and recorded the land use information of the corresponding surface layers; the feature ID is an incrementally generated combination of numbers and letters, which is equivalent to the unique name of each clipping surface layer.

[0076] Subsequently, based on the judgment system, the land survey quality inspectors used the segmentation module to segment several clipping surface layers along the map sheet boundary lines of two adjacent districts A and B. Then, the segmented clipping surface layers were merged according to their respective districts and counties. The merged clipping surface layers were denoted as surface layers PA and PB.

[0077] Subsequently, based on the judgment system, the land survey quality inspectors used the intersection module and formula (1) to calculate the line segment L and the surface layers PA and PB, and extracted the intersecting line segments LA and LB. Since the surface layers PA and PB are generated by cutting the map boundary line, and the clipped surface layer before cutting is generated by buffering the line segment L, calculating the geometric intersection of the line segment L and the surface layers PA and PB is essentially finding the part of the line segment L that intersects with the map boundary line.

[0078] Then, based on the judgment system, the land survey quality inspectors used the intersection module and formula (2) to calculate the length of each segment in the intersecting line segments LA and LB, and set the minimum segment length threshold to 1m. They then deleted the segments with a length less than 1m from the intersecting line segments LA and LB, and arranged the remaining segments in order from shortest to longest.

[0079] Roads and rivers have basic length and width. Line segments that are too short are obviously not the main structure of roads and rivers. Therefore, removing line segments that are too short can help reduce invalid calculations in the judgment system, save the computing power of the judgment system, and improve the operating efficiency of the judgment system.

[0080] Subsequently, based on the judgment system, the land survey quality inspectors used the intersection module and formula (3) to calculate the slopes of the intersecting line segments LA and LB in order from shortest to longest. They checked the line segments with slopes close to 0, slopes that do not exist, and slopes that are very large. They also analyzed the positional relationship between the starting point, ending point, and intermediate point of the line segment, thereby extracting the line segments that conform to the characteristics of U-shaped line segments, which are denoted as line segments UA and UB.

[0081] After a U-shaped line segment is divided by the map boundary line, a smaller U-shaped line segment usually remains, and both endpoints of this U-shaped line segment lie on the map boundary line. Therefore, calculating the slope of the U-shaped line segment using the coordinates of the two endpoints is often equivalent to calculating the slope of a horizontal or vertical line, which is prone to errors and thus distinguishes the U-shaped line segment from other line segments. The U-shaped line segment essentially represents a U-shaped road or river, so the location of the U-shaped road or river can be determined based on the location of the U-shaped line segment.

[0082] Then, based on the judgment system, the land survey quality inspectors use the comparison module to extract the clipping surface layer adjacent to the line segment UA in the surface layer PA, denoted as Ai; where the line segment UA is adjacent to at least two clipping surface layers, and the clipping surface layer Ai actually refers to a certain clipping surface layer in a set of clipping surface layers, i = 1, 2, 3...; read the feature ID of the clipping surface layer Ai, and search for the clipping surface layer adjacent to the clipping surface layer Ai in the surface layer PB, denoted as Bi.

[0083] In this embodiment, clipping plane layers Ai and Bi are essentially formed by dividing a clipping plane layer by the map sheet boundary line. Therefore, when the land survey data of two adjacent counties A and B have consistent edges, clipping plane layer Ai is only adjacent to one clipping plane layer Bi, and clipping plane layers Ai and Bi have the same feature ID. However, when the land survey data of two adjacent counties A and B have inconsistent edges, the original clipping plane layer itself has an error, causing clipping plane layer Ai to correspond to more than two clipping plane layers Bi at the same time, and the feature ID of clipping plane layer Ai is not the same as the feature ID of all clipping plane layers Bi.

[0084] Subsequently, the land survey quality inspectors analyzed the quantitative relationship between clipping surface layers Ai and Bi, and compared the feature IDs and land use information of clipping surface layers Ai and Bi. In this embodiment, clipping surface layer Ai corresponds to a unique clipping surface layer Bi. Clipping surface layers Ai and Bi have the same feature ID, and the land use information of clipping surface layers Ai and Bi is completely consistent. Therefore, the comparison module outputs the feature code TFMA(1,1) which expresses that the boundary and land use boundary of clipping surface layer Ai are completely consistent. The feature code includes feature ID, number, boundary consistency check result (0 or 1, 0 represents inconsistency, 1 represents consistency), and land use consistency check result (0 or 1).

[0085] Meanwhile, land survey quality inspectors extract the clipping surface layer Bn adjacent to line segment UB in the surface layer PB, n = 1, 2, 3...; read the feature ID of the clipping surface layer Bn, and search for the clipping surface layer An adjacent to the clipping surface layer Bn in the surface layer PA.

[0086] Subsequently, the land survey quality inspectors analyzed the quantitative relationship between clipping surface layers Bn and An, and compared the land use information of clipping surface layers Bn and An. In this embodiment, clipping surface layer Bn corresponds to a unique clipping surface layer An. Clipping surface layers Bn and An have the same feature ID, and the land use information of clipping surface layers Bn and An is completely consistent. Therefore, the comparison module outputs the feature code TFMB(1,1) that expresses the complete consistency between the boundary and land use border of clipping surface layer Bn.

[0087] Then, the land survey quality inspectors use the merging module to search for clipping surface layers in the surface layer PB that have the same feature ID as the clipping surface layer Ai. After merging with the clipping surface layer Ai, a new clipping surface layer is formed, denoted as NAi. The feature code TFMA is read to analyze the consistency between the boundary and land type of the clipping surface layer NAi. In this embodiment, the boundary and land type of the clipping surface layer NAi are completely consistent. Therefore, the merging module outputs the feature code TFMNA(1,1) which expresses that the boundary and land type of the clipping surface layer NAi are completely consistent.

[0088] Subsequently, land survey quality inspectors searched for clipping surface layers with the same feature ID as clipping surface layer Bn in surface layer PA, merged them with clipping surface layer Bn to form a new clipping surface layer, denoted as NBn; read the feature code TFMB, and analyzed the consistency of the boundary and land type edge of clipping surface layer NBn; in this embodiment, the boundary and land type edge of clipping surface layer NBn are completely consistent, so the merging module outputs the feature code TFMNB(1,1) that expresses the complete consistency of the boundary and land type edge of clipping surface layer NBn.

[0089] Finally, based on the judgment system, the land survey quality inspectors used the result display module to query the feature codes TFMNA and TFMNB, and searched for clipping surface layers NAi and NBn whose boundaries and land categories were inconsistent. In this embodiment, the result display module returned a search failure message, indicating that the boundaries and land categories of the land survey data were completely consistent.

[0090] This embodiment accurately captures U-shaped roads and rivers by converting the polygon layer into a line layer and performing intersection calculations on the line layer. It further analyzes the edge consistency of such linear features, solving the problem of lacking edge judgment for U-shaped roads and rivers in the prior art. By setting a minimum line segment length threshold, tiny line segments are excluded, and intersecting line segments with a certain length are selected, reducing invalid calculations and improving system operating efficiency. By setting feature IDs and feature codes, the polygon and line layers retain the initial polygon layer data and land use information after multiple segmentations and mergings, enabling repeated verification of inspection results and further improving the accuracy of land survey quality inspection.

[0091] Example 2:

[0092] like Figure 1-2 As shown in Figure 4, this embodiment takes the inspection of land survey data of two adjacent counties A and B by land survey quality inspectors as an example; in this embodiment, the boundaries of the land survey data are consistent, but the land categories are inconsistent.

[0093] This embodiment is basically the same as embodiment 1, except that in this embodiment, the land use information of the clipping surface layers Ai and Bi is inconsistent, and the feature code output by the comparison module is TFMA(1,0);

[0094] The land use information of clipping plane layer Bn and clipping plane layer An is inconsistent, and the feature code output by the comparison module is TFMB(1,0);

[0095] The land cover information of the clipping surface layer NAi is inconsistent, and the feature code output by the merging module is TFMNA(1,0);

[0096] The land use information of the clipping surface layer NBn is inconsistent, and the feature code output by the merging module is TFMNB(1,0);

[0097] Therefore, in this embodiment, the land survey quality inspectors use the result display module to query the feature codes TFMNA and TFMNB, search for feature codes that are inconsistent between the boundary and land category. After a successful search, they mark the corresponding clipping surface layers NAi and NBn, highlight the surface layers corresponding to clipping surface layers NAi and NBn, and display the inconsistent land category boundaries of the surface layers according to the feature codes TFMNA and TFMNB, thus completing the judgment of the boundary relationship of the U-shaped vector graphics.

[0098] This embodiment utilizes information recorded by various feature codes to identify and filter U-shaped roads and rivers with inconsistent land use boundaries, reducing the workload of manual identification and improving the efficiency of land survey quality inspection.

[0099] Example 3:

[0100] like Figure 1-2 As shown in Figure 5, this embodiment takes the inspection of land survey data of two adjacent counties A and B by land survey quality inspectors as an example; in this embodiment, the boundary of the land survey data is completely inconsistent, but the land type is consistent.

[0101] This embodiment is basically the same as embodiment 1, except that in this embodiment, the clipping surface layer Ai corresponds to more than three clipping surface layers Bi. Therefore, the boundary edges of clipping surface layers Ai and Bi are inconsistent, and the feature code output by the comparison module is TFMA(0,1).

[0102] The clipping plane layer Bn corresponds to more than three clipping plane layers An. Therefore, the boundary edges of clipping plane layers Bn and An are inconsistent. The feature code output by the comparison module is TFMB(0,1).

[0103] The boundary edges of the clipping plane layer NAi are inconsistent, and the feature code output by the merging module is TFMNA(0,1).

[0104] The boundary edges of the clipping plane layer NBn are inconsistent, and the feature code output by the merging module is TFMNB(0,1).

[0105] Therefore, in this embodiment, the land survey quality inspectors use the result display module to query the feature codes TFMNA and TFMNB, search for feature codes that are inconsistent between the boundary and land category. After a successful search, they mark the corresponding clipping surface layers NAi and NBn, highlight the surface layers corresponding to clipping surface layers NAi and NBn, and display the inconsistent boundary edges of the surface layers according to the feature codes TFMNA and TFMNB, thus completing the judgment of the edge connection relationship of the U-shaped vector graphics.

[0106] This embodiment utilizes information recorded by various feature codes to identify and filter U-shaped roads and rivers with inconsistent boundary connections, reducing the workload of manual identification and improving the efficiency of land survey quality inspection.

[0107] Example 4:

[0108] like Figure 1-2 As shown in Figure 6, this embodiment takes the inspection of land survey data of two adjacent counties A and B by land survey quality inspectors as an example. In this embodiment, the boundary of the land survey data is inconsistent, but the land type is consistent.

[0109] This embodiment is basically the same as embodiment 3, except that in this embodiment, the clipping surface layer Ai corresponds to at least two clipping surface layers Bi. Therefore, the boundary edges of clipping surface layers Ai and Bi are inconsistent, and the feature code output by the comparison module is TFMA(0,1).

[0110] The clipping plane layer Bn corresponds to at least two clipping plane layers An. Therefore, the boundary edges of clipping plane layers Bn and An are inconsistent, and the feature code output by the comparison module is TFMB(0,1).

[0111] The subsequent results of this embodiment are the same as those of Embodiment 3. This embodiment illustrates that whether the boundary alignment of the land survey data is completely inconsistent or partially inconsistent does not affect the inspection effect of the system, demonstrating the wide applicability of this system.

[0112] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A system for determining the edge-joining relationship of a U-shaped vector graphic, characterized in that, include: The client is used to load land survey data from two adjacent counties, A and B, visualize the land survey data, and provide an interactive interface; The boundary selection module is used to read the map boundary lines, surface layer data and land use information of two adjacent counties A and B in the land survey data, and select the surface layers that the map boundary lines pass through. The layer conversion module converts the selected face layer into a line layer based on the selection result of the boundary selection module, and then merges all the line layers. The merged line layer is denoted as line segment L. The buffer processing module is used to buffer the line segment L, generate a buffer surface layer, and use the buffer surface layer to clip the surface layer selected by the boundary selection module, retaining the area overlapping with the buffer surface layer, and generating several clipping surface layers. The feature module is used to set feature IDs for the clipped surface layer generated by the buffer processing module and save the land cover information of the original surface layer. The segmentation module divides the clipping surface layer generated by the buffer processing module along the map sheet boundary line, and then merges the segmented clipping surface layers according to the district / county where they are located. The merged layers are denoted as surface layers PA and PB. The intersection module is used to calculate the geometric intersection of line segment L and surface layers PA and PB, extract the intersecting line segments, denoted as intersecting line segments LA and LB, delete the small line segments in intersecting line segments LA and LB, and identify the U-shaped line segments in intersecting line segments LA and LB, denoted as line segments UA and UB. The comparison module is used to extract the clipping surface layer adjacent to line segment UA in the surface layer PA, denoted as Ai, and search for the clipping surface layer adjacent to clipping surface layer Ai in the surface layer PB, denoted as Bi. It analyzes the quantitative relationship between clipping surface layers Ai and Bi, compares the feature IDs and land use information of clipping surface layers Ai and Bi, analyzes the boundary and land use edge consistency of clipping surface layer Ai, and outputs the feature code TFMA expressing the boundary and land use edge consistency of clipping surface layer Ai. The comparison module is also used to extract the clipping surface layer adjacent to line segment UB in the surface layer PB, denoted as Bn, and search for the clipping surface layer Bn adjacent to clipping surface layer An in the surface layer PA. It analyzes the quantitative relationship between clipping surface layers Bn and An, compares the feature IDs and land use information of clipping surface layers Bn and An, analyzes the boundary and land use edge consistency of clipping surface layer Bn, and outputs the feature code TFMB expressing the boundary and land use edge consistency of clipping surface layer Bn. The merging module is used to search for clipping polygon layers adjacent to clipping polygon layer Ai in polygon layer PB, merge them with clipping polygon layer Ai to form a new clipping polygon layer, denoted as NAi, analyze the boundary and land type edge consistency of clipping polygon layer NAI, and output the feature code TFMNA expressing the boundary and land type edge consistency of clipping polygon layer NAI; the merging module is also used to search for clipping polygon layers adjacent to clipping polygon layer Bn in polygon layer PA, merge them with clipping polygon layer Bn to form a new clipping polygon layer, denoted as NBn, analyze the boundary and land type edge consistency of clipping polygon layer NBn, and output the feature code TFMNB expressing the boundary and land type edge consistency of clipping polygon layer NBn. The result display module is used to query the feature codes TFMNA and TFMNB and display the query results.

2. The system for determining the edge-joining relationship of a U-shaped vector graphic as described in claim 1, characterized in that, The boundary selection module is used to select the surface layer through which the map boundary line passes from the land survey data, detect the edge of the surface layer, extract the pixel value information of the surface layer, find adjacent pixels with different pixel values, and set the pixel as a candidate edge point. The above operation is repeated until all candidate edge points are determined, and all candidate edge points are connected to form an edge line.

3. The system for determining the edge relationship of a U-shaped vector graphic as described in claim 2, wherein the layer conversion module is used to separate the edge lines from the surface layers, save the edge lines separately to form line layers, and merge all the line layers.

4. The system for determining the edge-joining relationship of a U-shaped vector graphic as described in claim 1, characterized in that, The buffer processing module is used to set the buffer radius of line segment L and generate a buffer surface layer based on the buffer radius.

5. The system for determining the edge-joining relationship of a U-shaped vector graphic as described in claim 1, characterized in that, The intersection module uses an intersection function to calculate the intersection of line segment L and surface layers PA and PB, extracting the intersecting line segments LA and LB, as shown in the following formula: LA = ST_Intersection(L, PA) LB = ST_Intersection(L, PB) In the formula, ST_Intersection() is the intersection function, L represents line segment L, and PA and PB represent surface layers PA and PB, respectively; The intersection module calculates the length of each segment in the intersecting line segments LA and LB using the following formula: ； In the formula, (x1,y1) and (x2,y2) are the coordinates of the endpoints of the line segment, sqrt() is the square root function, and length is the length; The intersection module sets a line segment length threshold and deletes line segments with lengths less than the threshold from the intersecting line segments LA and LB; The intersection module calculates the slope of each segment in the intersecting line segments LA and LB using the following formula: ； In the formula, (x1,y1) and (x2,y2) are the coordinates of the endpoints of the line segment, and slope is the slope.

6. The system for determining the edge-joining relationship of a U-shaped vector graphic as described in claim 1, characterized in that, The comparison module is used to query all clipping surface layers adjacent to clipping surface layers Ai and Bn in surface layers PA and PB, and compare the feature ID and land use information of each adjacent clipping surface layer with clipping surface layers Ai and Bn.

7. The system for determining the edge-joining relationship of a U-shaped vector graphic as described in claim 1, characterized in that, The merging module is used to query all feature codes TFMA and TFMB to determine the boundary and land class contiguousness of the clipping surface layers NAi and NBn.

8. The system for determining the edge-joining relationship of a U-shaped vector graphic as described in claim 1, characterized in that, The result display module is used to query the feature codes TFMNA and TFMNB, search for feature codes whose boundaries and land use categories are inconsistent. After a successful search, the corresponding clipping surface layers NAi and NBn are marked, the surface layers corresponding to clipping surface layers NAi and NBn are highlighted, and the boundary of the surface layer is inconsistent with the land use category according to the feature codes TFMNA and TFMNB.

9. A method for determining the edge-joining relationship of a U-shaped vector graphic, characterized in that, A system for determining the edge-joining relationships of a U-shaped vector graphic as described in any one of claims 1-8, comprising the following steps: S1, load land survey data, read map boundary lines, surface layer data and land type information of two adjacent counties A and B, select the surface layer through which the map boundary line passes, convert the surface layer into a line layer, and then merge all the line layers. The merged line layer is denoted as line segment L. S2, set a buffer for line segment L, generate a buffer surface layer, use the buffer surface layer to clip the surface layer selected in step S1, retain the area overlapping with the buffer surface layer, generate several clipped surface layers, set a feature ID for each clipped surface layer, and each clipped surface layer saves the land use information of the original surface layer. S3, divide the clipping surface layer along the map boundary lines of the two adjacent districts A and B, and then merge the divided clipping surface layers according to the districts and counties they belong to. The merged layers are denoted as surface layers PA and PB. S4, calculate the geometric intersection of line segment L with surface layer PA and surface layer PB respectively, extract the intersecting line segments, and denot them as intersecting line segments LA and LB, identify the U-shaped line segments in intersecting line segments LA and LB, and denot them as line segments UA and UB; S5. Extract the clipping surface layer adjacent to line segment UA from the surface layer PA, denoted as Ai. Search for the clipping surface layer adjacent to clipping surface layer Ai in the surface layer PB, denoted as Bi. Analyze the quantitative relationship between clipping surface layers Ai and Bi, compare the feature ID and land use information of clipping surface layers Ai and Bi, analyze the boundary and land use edge connection consistency of clipping surface layer Ai, and output the feature code TFMA expressing the boundary and land use edge connection consistency of clipping surface layer Ai; S6. Search for the clipping surface layer adjacent to clipping surface layer An in the surface layer PB, merge it with clipping surface layer An to form a new clipping surface layer, denoted as NAi. Read the feature code TFMA, analyze the boundary and land use edge connection consistency of clipping surface layer NAi, and output the feature code TFMNA expressing the boundary and land use edge connection consistency of clipping surface layer NAi; S7. Extract the clipping plane layer adjacent to line segment UB from the plane layer PB, denoted as Bn. Search for the clipping plane layer adjacent to clipping plane layer Bn in the plane layer PA, denoted as An. Analyze the quantitative relationship between clipping plane layer Bn and clipping plane layer An. Compare the feature ID and land use information of clipping plane layer Bn and clipping plane layer An. Analyze the boundary and land use edge connection consistency of clipping plane layer Bn. Output the feature code TFMB that expresses the boundary and land use edge connection consistency of clipping plane layer Bn. S8. Search for clipping surface layers adjacent to clipping surface layer Bn in surface layer PA, merge them with clipping surface layer Bn to form a new clipping surface layer, denoted as NBn, read the feature code TFMB, analyze the boundary and land type edge consistency of clipping surface layer NBn, and output the feature code TFMNB that expresses the boundary and land type edge consistency of clipping surface layer NBn. S9, query the feature codes TFMNA and TFMNB, find the clipping surface layers NAi and NBn where the boundary and land type are inconsistent, and complete the judgment of the edge relationship of the U-shaped vector graphics.

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