CN111260758B - Method and system for constructing hierarchical relationship of planar administrative region - Google Patents
Method and system for constructing hierarchical relationship of planar administrative region Download PDFInfo
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Abstract
The invention relates to a method and a system for constructing a hierarchical relationship of a planar administrative region, and belongs to the technical field of spatial data processing of a geographic information system. The method carries out spatial relationship operator reconstruction by defining the coverage error area and calculating the area of the coverage error area, judges whether the two planar administrative areas have coverage hierarchical relationship by using the reconstructed spatial relationship operator, adopts the coverage error ratio to describe the spatial relationship by the reconstructed spatial relationship operator, judges the coverage relationship according to the coverage error ratio, avoids judging that the two planar areas are judged to be overlapping because of smaller overlapping caused by errors, and improves the accuracy of the judgment of the coverage relationship.
Description
Technical Field
The invention relates to a method and a system for constructing a hierarchical relationship of a planar administrative region, and belongs to the technical field of spatial data processing of a geographic information system.
Background
Administrative regions are regional division policies executed by the nation for hierarchical management, and China is mainly divided into three administrative levels, namely, provincial administrative districts, county administrative districts and rural administrative districts. In a geographic information system, the organization and management of the spatial data of the administrative regions of different levels mainly adopts a hierarchical management mode to organize the spatial data of the administrative regions of different levels in different layers, which is convenient for the organization and management of the spatial data, but splits the hierarchical relationship among the administrative regions of different levels, namely, only realizes the horizontal management of the spatial data, but neglects the longitudinal management.
The method mainly comprises two ways of constructing the planar spatial data of the administrative regions among different levels, wherein one way is an interactive way, namely the spatial relation of planar elements among different levels is determined through a graph interactive way; and the other method is automatic construction, namely, the hierarchical relationship among the planar elements is calculated and constructed through a spatial relationship operator. For spatial data with a small data volume and a small hierarchical relationship, an interactive mode can be adopted for construction, but for spatial data with a large data volume and a large hierarchical relationship, the interactive mode construction is large in workload and prone to errors, and therefore an automatic construction mode is often adopted. The key of the automatic construction mode lies in spatial relation operators, currently, the most representative of a calculation model of spatial data topological relation is a 9-intersection model, as shown in fig. 1, the calculation models of "plane-plane spatial relation" mainly include an isolated (discrete), a connected (meet), an overlapped (overlap), an equal (equal), an included (contact), an inside (inside), an overlay (cover) and an overlaid (overlaid by), and the calculation models can be mainly used for the calculation of hierarchical relation of a planar administrative region, including, overlaying and the like. For the cases 1 and 2 in fig. 2-1 and 2-2, the existing spatial relationship operator can make accurate calculation and judgment, but for the case 3 (as shown in fig. 2-3), the spatial relationship operator often judges that the data are overlapped, so that a hierarchical relationship cannot be constructed, but actually, the overlapped part of the areas a and B is small, which is often due to an error caused when the administrative region boundary is acquired, and the situation is very common in administrative region data of different sources.
Disclosure of Invention
The invention aims to provide a method and a system for constructing a hierarchical relationship of a planar administrative region, which aim to solve the problem that the judgment of a coverage relationship is easy to make mistakes in the current hierarchical relationship construction process.
The invention provides a method for constructing a hierarchical relationship of a planar administrative region to solve the technical problem, which comprises 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, wherein the zero spatial relationship operator is equal to a coverage error ratio, and the coverage error ratio refers to the ratio of the coverage error area to the coverage area of a covered element falling into the coverage element;
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.
The invention also provides a system for constructing the hierarchical relationship of the planar administrative regions, which comprises a memory, a processor and a computer program stored on the memory and running on the processor, wherein the processor is coupled with the memory, and the processor executes the computer program to realize the method for constructing the hierarchical relationship of the planar administrative regions.
The method carries out spatial relationship operator reconstruction by defining the coverage error area and calculating the area of the coverage error area, judges whether the two planar administrative areas have coverage hierarchical relationship by using the reconstructed spatial relationship operator, adopts the coverage error ratio to describe the spatial relationship by the reconstructed spatial relationship operator, judges the coverage relationship according to the coverage error ratio, avoids judging that the two planar areas are judged to be overlapping because of smaller overlapping caused by errors, and improves the accuracy of the judgment of the coverage relationship.
Further, the present invention provides a process for determining the coverage error region, wherein the process for determining the coverage error region in 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 sets of points truncated by the two selected intersections on the boundary of the covered polygonAnd P is i And covering the set P of points on the polygon boundary truncated by the two selected intersection points i ′;
C. And C, forming polygons by the point sets obtained in the step B according to a set sequence, and covering the error area to form a polygon set.
Further, the invention provides a determination process of the covering polygon, which comprises the following steps:
a. from the set of intersections { p 1 ,p 2 ,...,p n Get the head and end points of intersection p 1 And p n Determining the intersection point p of the head and the tail of the quilt 1 And p n The set P of points of the 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 (1) form a polygon according to a certain sequence, and the polygon is a covering polygon.
Further, in order to facilitate data storage and organization, the step 3) adopts a tree structure to perform data organization on the coverage hierarchical relationship.
Further, in order to improve the accuracy and efficiency of the construction of the hierarchical relationship, the method further comprises the step of preprocessing the space geometric data of the elements of the obtained face-shaped administrative region, wherein the preprocessing comprises merging elements with the same name and/or filtering scattered polygons.
Further, in order to conveniently calculate the area of the coverage error region, the area of the coverage error region is obtained by adopting a polygon area calculation formula, and the adopted calculation formula is as follows:
wherein S error To cover the area of the error region, (x) i ,y i ) Is composed ofThe i-th vertex coordinates of the polygon covering the error region are constructed.
Furthermore, in order to realize the all-round judgment of the spatial relationship, the method also comprises the step of judging the spatial inclusion relationship, and if the spatial geometric data of one element completely contains the spatial geometric data of another element, judging that the two elements form the included hierarchical relationship.
Drawings
FIG. 1 is a schematic diagram of a prior art 9 surface-to-surface topology;
FIG. 2-1 is a relationship diagram of case 1 in a face-to-face topology relationship;
FIG. 2-2 is a relationship diagram of case 2 in a face-to-face topology relationship;
2-3 are relationship diagrams for case 3 (overlay) in a face-to-face topology relationship;
FIG. 3 is a flow chart of the method for constructing a hierarchical relationship of a planar administrative region according to the present invention;
FIG. 4 is a schematic representation of spatial relationship operator reconstruction in the present invention;
FIG. 5 is a schematic diagram of an embodiment of the present invention covering an error region;
FIG. 6 is a schematic diagram of an overlay error zone formed by two polygons according to an embodiment of the present invention.
Detailed Description
The following further describes embodiments of the present invention with reference to the drawings.
Method embodiment
The invention provides a construction method of a hierarchical relationship of a planar administrative region, aiming at the problem that the coverage relationship is easy to be judged as an overlapping relationship in the construction process of the hierarchical relationship of the planar administrative region at present. The implementation flow is shown in fig. 3, and the specific implementation process is as follows.
1. Spatial geometrical data of the planar administrative area elements are acquired.
The spatial geometry data of the planar administrative area element according to the present invention is coordinate data of the planar administrative area, and may be various electronic map data. In the GIS vector data model, elements are the encapsulation of geometric and attribute information, and the geometric of administrative elements are polygons (since it is the region that is the polygon, if it is the administrative center that is the point). After the data are obtained, the data need to be preprocessed, and the data preprocessing mainly filters the data which do not meet the requirements, so as to facilitate subsequent processing and reduce the influence of interference data on calculation and judgment results. Firstly, merging elements with the same name, namely merging the elements with the same name in the elements into one element; secondly, scattered polygon filtering is performed, spatial geometry data of the elements of the planar administrative area are often composite geometry (i.e. multi-polygon), but scattered small polygons are not beneficial to data processing, so that the interference data need to be filtered, that is, each element only keeps the part with the largest area, and the rest scattered polygons are deleted.
2. And reconstructing the spatial relation operator.
The existing spatial relation operator can not meet the judgment of the hierarchical relation among the planar spatial data, so the spatial relation operator needs to be reconstructed, which is also the core part of the invention. The basic scheme of spatial relationship operator reconstruction is shown in fig. 4, and firstly, the existing original meta-operator is expanded and improved to form an improved meta-operator, and then, the reconstructed operator is formed through combination and rearrangement, so that the construction of the hierarchical relationship is realized. The original meta-operator refers to the existing basic calculation operators such as length, angle, area, relation (including, intersecting, separating, etc.), line segment intersection point, distance from point to line segment, etc., and these operators are the basis of the algorithm of the present invention, but these operators are all the basis of comparison, so that it is necessary to expand (or encapsulate) on the basis of them to make them meet higher requirements, such as constructing a covering polygon, calculating the area of covering error, etc., the final reconstruction operator is the highest level encapsulation of the present invention, its input is two polygons which need to be subjected to level relation judgment, and its output is whether to form a level relation.
The reason for forming the coverage error region is mainly the coverage of two data (when data production is carried out, an upper administrative area and a lower administrative area are often two different layers) in different acquisition processes, and the error region is formed because the data of the two manually acquired layers cannot be completely matched. Defining overlay error zone as shown in fig. 5, if the boundary portions of two elements are similar, the polygonal zone formed between the boundary lines of the similar portions is called an overlay error zone; as shown in fig. 6, the administrative area a is an overlay polygon, the administrative area B is an overlay polygon, the light area is an overlay error area, and the dark area is an area where the overlay polygon falls into the overlay polygon.
When the coverage error region is constructed, because a space operator for directly obtaining the intersection result of the two regions does not exist, the existing operator needs to be expanded and reformed. Firstly, the intersection point between each edge of two polygons is calculated to form an intersection point set { p } 1 ,p 2 ,...,p n }. Two intersection points p are taken in sequence i And p i-1 Separately calculating the covered polygon boundary by p i And p i-1 Set of truncated points P i And covering the polygon boundary by p i And p i-1 Set of truncated points P i ', set P points i And P i ' the polygons are formed according to the clockwise (or anticlockwise) order, and all scattered polygons are organized into a set, namely, a polygon set covering the error region is obtained.
For covering polygons falling into a covering element, the head and tail intersection points p are taken 1 And p n Calculating a set P of points of the covered polygon truncated by the node pair falling inside the covered polygon inside Taking out the set P of the points when all i are odd number in the previous step i ', and P is the set of points when all i are even numbers i All the point sets are formed into boundary point set P according to the sequence of ending connection boundary (only one node remains where the end meets), and finally P is added inside And P boundary The nodes in the method are organized into polygons according to the clockwise (or anticlockwise) sequence, namely, covering polygons are formedAnd (4) shaping.
Recording the area of the coverage error region as S error The area of the error region can be calculated by a polygon area calculation formula, that is:
wherein (x) i ,y i ) Is the i-th vertex coordinate of the polygon covering the error area.
Similarly, the area of the region in which the covered element falls within the coverage element can be calculated by the above equation. And calculating the ratio of the coverage error area to the coverage area of the covered element falling into the covering element, and defining the ratio as a coverage error ratio rho, wherein the coverage error ratio rho is the reconstructed spatial relation operator.
ρ=S error /S cover
3. And judging the spatial hierarchical relationship.
And judging whether the two planar administrative regions meet the coverage relation according to the reconstructed relation operator, specifically, judging the coverage error ratio, giving a threshold value epsilon, and if the coverage error ratio rho between the two planar administrative regions is larger than the threshold value epsilon, indicating that the two planar administrative regions are in the coverage relation.
The invention can accurately judge the covering relation and judge the inclusion relation, and the judgment of the relation adopts the existing judgment mode of the face inclusion relation, and mainly judges whether one of two face administrative areas contains the other.
When the hierarchical relationship is constructed between more than two image layers of the spatial data of the planar administrative region, the construction sequence needs to be determined, the invention adopts a manual appointed mode to arrange the image layer with higher level in the front and the image layer with lower level in the back, and when the hierarchical relationship is constructed, the hierarchical relationship of the elements between every two image layers is constructed in sequence according to the arrangement sequence, but the image layer element arranged in the front is ensured to contain (or cover) the image layer element arranged in the back, but the image layer element arranged in the back can not contain (or cover) the image layer element arranged in the front.
4. And carrying out spatial hierarchy relational organization.
Because strict tree structures are arranged among administrative regions, the invention adopts a tree structure model to organize the spatial hierarchical relationship. In order to be decoupled from spatial data, the invention maps administrative region elements into nodes (nodes), acquires superior nodes through a getParantNode interface, acquires all inferior nodes of a current Node through a getChildNodes interface, and acquires the administrative region elements associated with the current Node through a getReferenceFeature interface. Therefore, the root node of each tree is the entrance of the whole hierarchical relationship, a plurality of root nodes form a forest by being organized together, and the root node of each tree can be managed. The invention adopts node set NodeCollection to organize the root nodes, obtains a certain root node through a getRootNode interface, and obtains all the root nodes through the getRootNodes interface.
System embodiment
The system for constructing the hierarchical relationship of the planar administrative regions comprises a memory, a processor and a computer program which is stored in the memory and runs on the processor, wherein the processor is coupled with the memory, and the method for constructing the hierarchical relationship of the planar administrative regions is realized when the processor executes the computer program. The specific implementation process of the method has been described in detail in the embodiment of the method, and is not described herein again.
The method carries out spatial relationship operator reconstruction by defining the coverage error area and calculating the area of the coverage error area, judges whether the two planar administrative areas have coverage hierarchical relationship by using the reconstructed spatial relationship operator, adopts the coverage error ratio to describe the spatial relationship by the reconstructed spatial relationship operator, judges the coverage relationship according to the coverage error ratio, avoids judging that the two planar areas are judged to be overlapping because of smaller overlapping caused by errors, and improves the accuracy of the judgment of the coverage relationship.
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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