CN111260758B - Method and system for constructing hierarchical relationship of planar administrative region - Google Patents

Abstract

The invention relates to a method and system for constructing hierarchical relations of planar administrative regions, and belongs to the technical field of geographic information system spatial data processing. The present invention reconstructs the spatial relationship operator by defining the coverage error area and calculating the area of the coverage error area, and uses the reconstructed spatial relationship operator to realize the judgment of whether there is a coverage hierarchy relationship between two planar administrative areas. After reconstruction The spatial relationship operator uses the coverage error ratio to describe the spatial relationship, and realizes the judgment of the coverage relationship according to the coverage error ratio, which avoids the overlapping relationship between two planar regions due to the small overlap caused by the error, and improves The accuracy of the coverage relationship judgment is improved.

Description

A method and system for constructing hierarchical relations of planar administrative regions

technical field

The invention relates to a method and system for constructing hierarchical relations of planar administrative regions, and belongs to the technical field of geographic information system spatial data processing.

Background technique

Administrative region is a regional division policy implemented by the country for hierarchical management. my country is mainly divided into three administrative levels: provincial administrative regions, county administrative regions, and township administrative regions. In the geographic information system, the organization and management of spatial data of different levels of administrative regions mainly adopts the method of layered management, and the spatial data of different levels of administrative regions are organized in different layers, which is convenient for the management of spatial data. Organizational management, but it splits the hierarchical relationship between different levels of administrative regions, that is, it only realizes the horizontal management of spatial data, but ignores the vertical management.

There are two main ways to construct the planar spatial data of administrative regions between different levels. One is interactive construction, that is, the spatial relationship of planar elements between different levels is determined through graphical interaction; the other is automatic construction, that is, through The spatial relationship operator calculates and constructs the hierarchical relationship between area elements. For spatial data with less data volume and fewer hierarchical relationships, interactive construction can be used, but for spatial data with larger data volumes and more hierarchical relationships, interactive construction is not only a heavy workload but also error-prone. Therefore, automatic construction is often used. The key to the automatic construction method lies in the spatial relationship operator. At present, the most representative calculation model for the topological relationship of spatial data is the 9-intersection model, as shown in Figure 1, which can calculate the main are disjoint, meet, overlap, equal, contain, inside, cover and covered by, and can be used for The calculation of the hierarchical relationship of area administrative regions mainly includes inclusion and coverage. For cases 1 and 2 in Figure 2-1 and Figure 2-2, the existing spatial relationship operators can make accurate calculations and judgments, but for case 3 (as shown in Figure 2-3) , is often judged to be overlapping by the spatial relationship operator, resulting in the inability to construct a hierarchical relationship, but in fact the overlapping area of A and B is very small, which is often due to the error caused when collecting the boundaries of administrative regions. And this situation is very common in administrative area data from different sources.

Contents of the invention

The purpose of the present invention is to provide a method and system for constructing the hierarchical relationship of planar administrative regions, so as to solve the problem that the judgment of coverage relationship is prone to error in the current hierarchical relationship construction process.

In order to solve the above-mentioned technical problems, the present invention provides a method for constructing the hierarchical relationship of planar administrative regions, which comprises the following steps:

1) Obtain the spatial geometry data of the planar administrative region elements;

2) Determine the coverage error area by using the relationship between the polygons where the two planar administrative area elements are located, and construct a spatial relationship operator based on the coverage error area and the area of the coverage error area. The zero spatial relationship operator is equal to the coverage error ratio, and the coverage error ratio refers to is the ratio between the area of the coverage error area and the coverage area of the covered element falling into the covered element;

3) According to the coverage error ratio, it is judged whether there is a coverage hierarchical relationship between the elements of the two planar administrative regions. If so, the data organization of the coverage hierarchical relationship is carried out to realize the construction of the hierarchical relationship of the planar administrative region.

The present invention also provides a system for constructing hierarchical relations of planar administrative regions, the construction system includes a memory and a processor, and a computer program stored in the memory and run on the processor, the processor and The memory is coupled, and when the processor executes the computer program, the method for constructing the hierarchical relationship of the area-like administrative regions according to the present invention is realized.

The present invention reconstructs the spatial relationship operator by defining the coverage error area and calculating the area of the coverage error area, and uses the reconstructed spatial relationship operator to realize whether there is a coverage hierarchy relationship between two planar administrative areas. After reconstruction The spatial relationship operator uses the coverage error ratio to describe the spatial relationship, and realizes the judgment of the coverage relationship according to the coverage error ratio, which avoids the small overlap caused by the error between two planar regions and is judged as an overlapping relationship, and improves The accuracy of the coverage relationship judgment is improved.

Further, the present invention provides the determination process of the coverage error area, and the determination process of the coverage error area in the step 2) is as follows:

A. Determine the intersection point between each side of the polygon where the two planar administrative regions are located, and obtain the set of intersection points {p ₁ ,p ₂ ,...,p _n } of the two planar administrative regions;

B. Select two intersection points p _i and p _i-1 from the intersection point set in turn, respectively determine the point set P i truncated by the two selected intersection points on the boundary of the covered polygon and the point set P _i selected on the boundary of the covered polygon Point set P _i ′ of two intersection points truncated;

C. Form the set of points obtained in step B into a polygon according to the set order, and cover the error area as the formed polygon set.

Further, the present invention provides the determination process of the coverage polygon, and the determination process of the coverage polygon is as follows:

a. Take out the first and last intersection points p ₁ and p _n from the set of intersection points {p ₁ ,p ₂ ,...,p _n }, and make sure that the covered polygon truncated by the first and last intersection points p ₁ and p _n falls inside the covering polygon The point set P _inside ;

b. Select the point where i is an odd number from the point set P _i , select the point when i is an even number from the point set P _i ', and form the boundary point set P _boundary with the points taken out according to the set order;

c. The points in the point sets P _inside and P _boundary are formed into a polygon in a certain order, and the polygon is the covering polygon.

Further, in order to facilitate data storage and organization, the step 3) uses a tree structure to organize data covering hierarchical relationships.

Further, in order to improve the accuracy and efficiency of the construction of the hierarchical relationship, the method also includes the step of preprocessing the spatial geometry data of the obtained planar administrative area elements, and the preprocessing includes merging elements with the same name and/or scattered polygons filter.

Further, in order to facilitate the calculation of the area of the coverage error area, the area of the coverage error area is obtained by using the polygonal area calculation formula, and the calculation formula used is:

Where S _error is the area of the coverage error area, and (xi _, y _i ) is the i-th vertex coordinate of the polygon that constitutes the coverage error area.

Furthermore, in order to realize the all-round discrimination of the spatial relationship, the method also includes the judgment of the spatial inclusion relationship. If the spatial geometric data of one element completely contains the spatial geometric data of another element, then it is determined that the two constitute the hierarchical relationship of inclusion. .

Description of drawings

Figure 1 is a schematic diagram of the existing 9 surface-to-surface topological relationships;

Figure 2-1 is a schematic diagram of the relationship of case 1 in the surface-to-surface topology relationship;

Figure 2-2 is a schematic diagram of the relationship of case 2 in the surface-to-surface topology relationship;

Figure 2-3 is a schematic diagram of the relationship of case 3 (coverage) in the surface-surface topology relationship;

Fig. 3 is a flow chart of the construction method of the hierarchical relationship of the area administrative regions of the present invention;

Fig. 4 is a schematic diagram of spatial relation operator reconstruction in the present invention;

FIG. 5 is a schematic diagram of a coverage error area according to an embodiment of the present invention;

Fig. 6 is a schematic diagram of a coverage error area composed of two polygons according to an embodiment of the present invention.

Detailed ways

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

method embodiment

Aiming at the problem that the coverage relationship is easily judged to be an overlapping relationship in the current construction process of the hierarchical relationship of the area-shaped administrative area, the present invention proposes a method for constructing the hierarchical relationship of the area-shaped administrative area. The construction method defines the coverage error area and calculates The coverage error area is reconstructed by the spatial relationship operator, and the reconstructed spatial relationship operator is used to judge whether there is a coverage hierarchy relationship between the two planar administrative areas. The implementation process is shown in Figure 3, and the specific implementation process is as follows.

1. Obtain the spatial geometry data of the planar administrative area elements.

The spatial geometry data of the planar administrative area elements in the present invention refers to the coordinate data of the planar administrative area, which may be various electronic map data. In the GIS vector data model, elements are the encapsulation of geometric figures and attribute information, and the geometric figures of administrative area elements are polygons (since it is a region, it is a polygon, and if it is an administrative center, it is a point). After obtaining the above data, it is necessary to preprocess the data. Data preprocessing is mainly to filter the data that does not meet the requirements, so as to facilitate subsequent processing and reduce the impact of interference data on the calculation and judgment results. The first is the merging of elements with the same name, that is, merging the elements with the same name into one element; the second is the filtering of scattered polygons. The spatial geometric data of the area-like administrative area elements is often a composite geometry (that is, multi-faceted, MultiPolygon), but the scattered small polygons are not. It is beneficial to data processing, so it is necessary to filter out these interference data, that is, each element only retains the part with the largest area, and deletes the rest of the scattered polygons.

2. Reconstruct the spatial relation operator.

Existing spatial relationship operators cannot satisfy the judgment of the hierarchical relationship between planar spatial data, so it is necessary to reconstruct the spatial relationship operator, which is also the core part of the present invention. The basic scheme of spatial relationship operator reconstruction is shown in Figure 4. First, the existing original meta-operator is expanded and improved to form an improved meta-operator, and then the reconstruction operator is formed through combination and rearrangement. Then realize the construction of hierarchical relationship. The original element operator refers to the existing basic computing operators such as length, angle, area, relationship (including, intersecting, separating, etc.), line segment intersecting point, point to line segment distance, etc. These operators are the core of the algorithm of the present invention However, these operators are relatively basic, so they need to be extended (or encapsulated) on the basis to make them meet higher requirements, such as building coverage polygons, calculating coverage error areas, etc., and the final reconstruction operator is It is the highest-level encapsulation of the present invention. Its input is pairwise polygons that need to be judged on the hierarchical relationship, and its output is whether to form a hierarchical relationship.

The reason for the formation of the coverage error area is mainly the coverage caused by two sets of data (in data production, the upper-level administrative region and the lower-level administrative region are often two different layers) in different collection processes, because the two manually collected layers It is impossible to completely match the data, so the formation of this error area is inevitable. Defining the coverage error area is shown in Figure 5. If the boundary parts of two elements are similar, the polygonal area formed between the boundary lines of the similar parts is called the coverage error area; as shown in Figure 6, the administrative area A is the covered polygon , the administrative area B is the coverage polygon, the light area is the coverage error area, and the dark area is the area where the covered polygon falls into the coverage polygon.

When constructing the coverage error area, since there is no spatial operator that directly obtains the intersection result of two areas, the existing operator needs to be expanded and transformed. First calculate the intersection point between each side of the two polygons to form a set of intersection points {p ₁ ,p ₂ ,...,p _n }. Take two intersection points p _i and p _i-1 in turn, respectively calculate the set P _i of the points truncated by p _i and p _i-1 on the boundary of the covered polygon, and the set of points truncated by p _i and p _i-1 on the boundary of the covered polygon The set of points P _i ′, the point sets P _i and P _i ′ are composed of polygons in a clockwise (or counterclockwise) order, and all the scattered polygons are organized into a set to obtain a polygon set covering the error area.

For the covering polygon falling into the covering element, take the first and last intersection points p ₁ and p _n , calculate the point set P _inside of the covered polygon truncated by this node pair and fall inside the covering polygon, and take out all i in the previous step as The set of points P _i ′ when it is odd, and the set of points P _i when all i are even numbers, all point sets form the boundary point set P _boundary in the order of ending connection (only the same nodes at the ending connection are reserved a), and finally organize the nodes in P _inside and P _boundary into polygons in a clockwise (or counterclockwise) order, which constitutes a covering polygon.

Record the area of the coverage error area as S _error , and the area of the error area can be calculated by the polygon area calculation formula, namely:

Where ( _xi , _y ) is the i-th vertex coordinate of the polygon covering the error area.

Similarly, the area where the covered element falls into the covered element can also be calculated according to the above formula. Calculate the ratio between the area of the coverage error area and the coverage area of the covered element falling into the coverage element, and define the ratio as the coverage error ratio ρ, which is the reconstructed spatial relationship operator.

ρ=S _error /S _cover

3. Judgment of spatial hierarchical relationship.

According to the reconstructed relationship operator, it is judged whether the coverage relationship between two area-shaped administrative regions is consistent. Specifically, it is judged by judging the size of the coverage error ratio. Given a threshold ε, if the coverage between the two area-like administrative regions If the error ratio ρ is greater than the threshold ε, it indicates that there is a coverage relationship between the two planar administrative regions.

In addition to accurately determining the coverage relationship, the present invention can also determine the inclusion relationship. The judgment of this kind of relationship adopts the existing judgment method of the surface inclusion relationship, mainly to determine whether there is an inclusion relationship between two planar administrative regions. Another situation.

When constructing a hierarchical relationship between more than two planar administrative region spatial data layers, it is necessary to determine the construction order. In the present invention, the artificial designation method is adopted to arrange the layer with a higher level in front, and the layer with a lower level. Layers are arranged at the back. When constructing the hierarchical relationship, the hierarchical relationship between the elements of the two layers is constructed in sequence according to the order of arrangement, but it must be ensured that the layer elements arranged in the front include (or cover) the elements arranged in the back. Layer features, and the lower layer features cannot contain (or cover) the earlier layer features.

4. Carry out spatial hierarchical relationship organization.

Since the administrative regions have a strict tree structure, the present invention adopts a tree structure model to organize the spatial hierarchical relationship. In order to be able to decouple from spatial data, the present invention maps administrative area elements to nodes (Nodes), obtains superior nodes through the getParentNode interface, obtains all subordinate nodes of the current node through the getChildNodes interface, and obtains the administrative area associated with the current node through the getReferenceFeature interface element. In this way, the root node of each tree is the entrance of the entire hierarchical relationship, and multiple such root nodes are organized together to form a forest, as long as the root nodes of each tree are managed. The invention adopts the node collection NodeCollection to organize the root nodes, obtains a certain root node through the getRootNode interface, and obtains all the root nodes through the getRootNodes interface.

System embodiment

The system for constructing the hierarchical relations of area administrative regions of the present invention includes a memory and a processor, and a computer program stored in the memory and run on the processor, the processor is coupled with the memory, and the processor implements the present invention when executing the computer program The construction method of the hierarchical relationship of the planar administrative regions. The specific implementation process of the method has been described in detail in the embodiments of the method, and will not be repeated here.

The present invention reconstructs the spatial relationship operator by defining the coverage error area and calculating the area of the coverage error area, and uses the reconstructed spatial relationship operator to realize whether there is a coverage hierarchy relationship between two planar administrative areas. After reconstruction The spatial relationship operator uses the coverage error ratio to describe the spatial relationship, and realizes the judgment of the coverage relationship according to the coverage error ratio, which avoids the small overlap caused by the error between two planar regions and is judged as an overlapping relationship, and improves The accuracy of the coverage relationship judgment is improved.

Claims (6)

1. A construction method of a planar administrative region hierarchical relationship is characterized by comprising the following steps:

1) Acquiring space geometric data of a planar administrative region element;

2) Determining a coverage error area by utilizing the relationship between polygons of two planar administrative area elements, constructing a spatial relationship operator according to the coverage error area and the coverage error area, and enabling the spatial relationship operator to be equal to a coverage error ratio, wherein the coverage error ratio refers to the ratio between the coverage error area and the coverage area of a covered element falling into the coverage element;

the determination process of the coverage error area in the step 2) is as follows:

A. determining the intersection point between each side of the polygon where the two planar administrative regions are located to obtain an intersection point set { p) of the two planar administrative regions ₁ ,p ₂ ,...,p _n }；

B. Sequentially selecting two intersection points p from the intersection point set _i And p _i-1 Separately determining a set P of points truncated by two selected intersection points on the boundary of the covered polygon _i And covering the set P of points on the polygon boundary truncated by the two selected intersection points _i ′；

C. B, forming polygons by the point sets obtained in the step B according to a set sequence, and covering an error area to form a polygon set;

the determination of the overlay polygon is as follows:

a. from the set of intersections { p ₁ ,p ₂ ,...,p _n Take out the first and last intersection points p ₁ And p _n Determining the intersection point p of the head and the end of the quilt ₁ And p _n Set of points P of truncated covered polygon falling inside the covered polygon _inside ；

b. Set of slave points P _i Selecting the points with i as odd number, and collecting P from the point set _i ' if i is an even number, the points are selected and the points are formed into a boundary point set P according to a set sequence _boundary ；

c. Set of points P _inside And P _boundary The points in (A) form a polygon in a certain order, theThe polygon is a covering polygon;

3) And judging whether the two planar administrative area elements form a coverage hierarchical relationship according to the coverage error ratio, and if so, organizing data of the coverage hierarchical relationship to realize the construction of the planar administrative area hierarchical relationship.

2. The method for constructing a hierarchical relationship of a planar administrative area according to claim 1, wherein in the step 3), data organization is performed on the hierarchical relationship of the coverage by using a tree structure.

3. The method for constructing the hierarchical relationship of the planar administrative regions according to claim 1, further comprising a step of preprocessing the spatial geometry data of the planar administrative region elements, wherein the preprocessing includes homonymous element merging and/or scattered polygon filtering.

4. The method for constructing a hierarchical relationship between planar administrative regions according to claim 1, wherein the area of the coverage error region is obtained by using a polygon area calculation formula, and the calculation formula is as follows:

wherein S _error To cover the area of the error region, (x) _i ,y _i ) The ith vertex coordinate of the polygon forming the covered error region.

5. The method for constructing a hierarchical relationship between planar administrative regions as recited in claim 1, further comprising determining a spatial inclusion relationship, and if the spatial geometry data of one element completely contains the spatial geometry data of another element, determining that the spatial inclusion relationship is formed by the spatial inclusion relationship and the spatial geometry data of the other element.

6. A system for constructing an areal administrative region hierarchy, the system comprising a memory, a processor and a computer program stored in the memory and running on the processor, the processor being coupled to the memory, and the processor implementing the method of constructing an areal administrative region hierarchy according to any one of claims 1 to 5 when executing the computer program.

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