Dimensionality reduction method for surface artificial elements

Abstract

The present invention discloses a method for reducing the dimension of artificial planar elements, including obtaining the element features of planar elements in a large-scale topographic map, screening planar elements that need to be reduced in dimension by using area features, matching the side length features of the planar elements with the feature edge recognition conditions, screening out short feature edges, and counting the number of the screened short feature edges, if the number of short feature edges meets the condition for the dimensionality reduction, dividing the long feature edges of the planar elements according to the short feature edges, constructing virtual edges based on the nodes of the long feature edges, and sequentially connecting the midpoints of the short feature edges and the virtual edges to generate line elements, if the length of the line element exceeds the length threshold, reducing the planar elements into line elements, otherwise, reducing the planar elements into point elements. In this way, the planar elements can be reduced in dimension to point elements or line elements, and the degree of automatic processing of artificial elements in comprehensive mapping can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of digital computing or data processing equipment or methods specially suitable for specific applications, and in particular to a method for dimensionality reduction processing of surface artificial elements. Background Art

[0002] It is a common method in production to obtain a small-scale topographic map by reducing a large-scale topographic map. Due to the data carrying capacity and symbol display requirements, in the process of reduction, the surface artificial elements that meet certain conditions must be converted into linear elements or point elements. Artificial elements such as bridges, culverts, and houses account for a large proportion of elements in topographic maps. It is necessary to convert the surface elements that meet the conditions in the large-scale topographic map into corresponding linear elements or point elements.

[0003] The existing technology generally uses human-computer interaction to semi-automatically reduce the dimension of surface elements. According to the area, length and width of the surface elements, the surface elements are manually drawn into line elements or point elements. Although the surface elements can be reduced in dimension, the manual drawing is labor-intensive and prone to errors. Therefore, there is an urgent need for a technology that can improve the degree of automation of manual element processing. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention proposes a method for reducing the dimension of planar artificial elements, which can improve the degree of automatic processing of artificial elements in comprehensive mapping and reduce the workload and errors of manual drawing.

[0005] In a first aspect, a method for dimensionality reduction processing of planar artificial elements is provided, comprising:

[0006] Obtaining the element features of the surface elements in the large-scale topographic map, the element features include area features and the length features of each side;

[0007] Determine whether the area element needs to be reduced in dimension based on the area feature;

[0008] In response to the need to perform dimensionality reduction processing on the surface element, the edge length feature of each edge is matched with the characteristic edge recognition condition, the short characteristic edges of the surface element are screened out, and the number of the screened short characteristic edges is counted;

[0009] Determine whether further dimensionality reduction processing is required for the surface element based on the number of short feature edges;

[0010] In response to the need for further dimensionality reduction processing, the edges of the planar elements are divided according to the short characteristic edges to determine the long characteristic edges of the planar elements;

[0011] Construct virtual edges between long feature edges according to the position coordinates of each node of the long feature edge;

[0012] Connect the midpoints of the short feature edges and virtual edges in sequence to generate line features;

[0013] Determine whether the length of the line feature exceeds the length threshold. If the length of the line feature exceeds the length threshold, the surface feature is reduced to a line feature. Otherwise, the surface feature is reduced to a point feature.

[0014] In combination with the first aspect, in a first implementable manner of the first aspect, determining whether it is necessary to perform dimensionality reduction processing on the surface element by using the area feature includes:

[0015] The area feature is compared with the area threshold. If the area feature is smaller than the area threshold, the surface element needs to be processed for dimensionality reduction. Otherwise, the surface element does not need to be processed for dimensionality reduction.

[0016] In combination with the first implementable manner of the first aspect, in a second implementable manner of the first aspect, the characteristic edge recognition condition includes:

[0017]

[0018] Where L is the side length, α1 and α2 are the azimuths of two adjacent sides, θ is the angle threshold, and λ is the width threshold.

[0019] In combination with the second implementable manner of the first aspect, in a third implementable manner of the first aspect, the width threshold, the area threshold, and the length threshold are set according to the reduction scale.

[0020] In combination with the first aspect, in a fourth implementable manner of the first aspect, determining the long characteristic edge of the planar element includes: dividing the boundary of the planar element into two parts through the short characteristic edge, and forming the long characteristic edge with line segments of the two divided parts.

[0021] In combination with the first aspect, in a fifth implementable manner of the first aspect, constructing virtual edges between long feature edges according to the position coordinates of each node of the long feature edge includes:

[0022] Calculate the distance between each node of the long feature edge according to the corresponding position coordinates;

[0023] The distance between each node is compared with the distance threshold, and two nodes whose distance is less than the distance threshold are selected to form a virtual edge.

[0024] In combination with the fifth implementable method of the first aspect, in the sixth implementable method of the first aspect, if there is a special node in the long feature edge, and the distance between the special node and the nodes of other long feature edges is greater than a distance threshold, then the position point closest to the special node in other long feature edges is selected to form a virtual edge with the special node.

[0025] In combination with the sixth implementable manner of the first aspect, in a seventh implementable manner of the first aspect, the distance threshold is 1.5 times the width threshold.

[0026] In combination with the first aspect, in an eighth implementable manner of the first aspect, the coordinates of the point element are the midpoint of the line element, and the direction of the point element is the azimuth of the line element.

[0027] In a second aspect, a storage medium is provided, storing a computer program, which, when running, executes a method for dimensionality reduction processing of planar artificial elements such as the first aspect and any one of the first to eighth implementable methods of the first aspect.

[0028] Beneficial effect: The method for reducing the dimension of artificial surface elements of the present invention can reduce the dimension of surface elements into point elements or line elements. The processed point elements or line elements also conform to the overall shape of the original surface elements. The dimensionality reduction processing effect is good, can meet the actual production use, and improve the degree of automated processing of artificial elements in comprehensive mapping. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation of the present invention, the following will briefly introduce the drawings required for use in the specific implementation. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0030] Figure 1 A flow chart of a method for dimensionality reduction processing of planar artificial elements provided by an embodiment of the present invention;

[0031] Figure 2 A schematic diagram of a planar element subjected to dimensionality reduction processing provided by an embodiment of the present invention;

[0032] Figure 3 A schematic diagram of a long characteristic edge provided by an embodiment of the present invention;

[0033] Figure 4 A schematic diagram of a virtual edge provided by an embodiment of the present invention;

[0034] Figure 5 A schematic diagram of a line element provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0036] It should be understood that the "surface elements" in the embodiments of the present invention are "surface artificial elements". It should also be understood that the technical solution of the embodiments of the present invention is applicable to when a large-scale topographic map is reduced to a smaller-scale topographic map. Some surface artificial elements are too small in area and should be represented as linear elements or point elements on the small-scale topographic map. Therefore, it is necessary to reduce the dimensionality of these surface artificial elements with certain regular characteristics.

[0037] like Figure 1 The flowchart of the method for reducing the dimension of the planar artificial elements shown in FIG. 1 includes:

[0038] Step 1, obtaining the element features of the surface elements in the large-scale topographic map, the element features including the area features and the length features of each side;

[0039] Step 2: Determine whether the area element needs to be reduced in dimension by using the area feature;

[0040] In response to the need to perform dimensionality reduction processing on the surface element, the edge length feature of each edge is matched with the characteristic edge recognition condition, the short characteristic edges of the surface element are screened out, and the number of the screened short characteristic edges is counted;

[0041] Step 3: Determine whether the surface element needs to be further reduced in dimension according to the number of short feature edges;

[0042] In response to the need for further dimensionality reduction processing, the edges of the planar elements are divided according to the short characteristic edges to determine the long characteristic edges of the planar elements;

[0043] Step 4: construct virtual edges between long feature edges according to the position coordinates of each node of the long feature edge;

[0044] Step 5: Connect the midpoints of the short feature edges and the virtual edges in sequence to generate line features;

[0045] Step 6: Determine whether the length of the line element exceeds the length threshold. If the length of the line element exceeds the length threshold, reduce the dimension of the surface element to a line element. Otherwise, reduce the dimension of the surface element to a point element.

[0046] Specifically, first, the area data of each surface element in the large-scale topographic map and the length data of each edge, etc. can be obtained through the map information system. Then, it can be determined whether the surface element needs to be processed for dimensionality reduction based on the area data of the surface element, so as to automatically eliminate some surface elements with larger areas, replace the surface elements that are manually screened for dimensionality reduction, and improve the degree of automation of manual processing of artificial elements.

[0047] For the surface elements that need to be processed for dimensionality reduction, such as Figure 2The surface elements P1P2P3P4P5P6P7P8 shown can match the edge length data of each edge of the surface element with the preset feature edge recognition conditions, filter out short feature edges that meet the feature edge recognition conditions from all the edges of the surface element, and count the number of short feature edges contained in the surface element.

[0048] Afterwards, it can be determined whether the number of short feature edges of the planar element meets the dimensionality reduction condition. In this embodiment, the dimensionality reduction condition can be set to that the number of short feature edges does not exceed 2. That is, if the number of short feature edges exceeds 2, there is no need to further perform dimensionality reduction on the planar element. Because more than 2 short feature edges will divide the planar element into multiple parts, a simple line element cannot be obtained by dimensionality reduction of more than 2 long features.

[0049] For the surface elements that need further processing, the edges of the surface elements can be divided according to the short feature edges to determine the long feature edges of the surface elements. Then, virtual edges are constructed between the long feature edges, and the midpoints of the short feature edges and the virtual edges are connected in sequence to form the line elements corresponding to the surface elements. Finally, it is determined whether the length of the line element exceeds the preset length threshold. If it exceeds, the surface element is reduced to a line element. Otherwise, the surface element is reduced to a point element.

[0050] Therefore, the processing method of this embodiment can automatically screen the surface elements that need to be processed for dimensionality reduction, and can automatically perform dimensionality reduction on the surface elements to be processed according to the characteristics of the surface elements. The processed point elements or line elements also conform to the overall shape of the original surface elements. The dimensionality reduction processing effect is good, can meet actual production use, and improve the degree of automated processing of artificial elements in comprehensive mapping.

[0051] In this embodiment, optionally, determining whether it is necessary to perform dimensionality reduction processing on the surface element by using the area feature includes:

[0052] The area feature is compared with the area threshold. If the area feature is smaller than the area threshold, the surface element needs to be processed for dimensionality reduction. Otherwise, the surface element does not need to be processed for dimensionality reduction.

[0053] After obtaining the area data of the surface element, the area data can be compared with a preset area threshold. If the area of ​​the surface element is smaller than the area threshold, the surface element needs to be processed. If the area of ​​the surface element is larger than the area threshold, the surface element does not need to be processed.

[0054] The area threshold can be set according to the reduction scale. For example, if a 1:2000 scale topographic map is reduced to a 1:5000 scale topographic map, the area threshold can be set to 120m. 2, the area in the 1:2000 scale topographic map is less than 120m 2 All artificial surface elements need to be processed for dimensionality reduction. A 1:5000 scale topographic map is reduced to a 1:10000 scale topographic map, and the area threshold can be set to 480m 2 . The area in the 1:5000 scale topographic map is less than 480m 2 Artificial surface elements need to be processed by dimensionality reduction.

[0055] In this embodiment, optionally, the characteristic edge recognition condition includes:

[0056]

[0057] Where L is the side length, α1 and α2 are the azimuths of two adjacent sides, θ is the angle threshold, and λ is the width threshold.

[0058] For the surface elements that need to be processed by dimensionality reduction, the edge length feature of each edge of the surface element can be compared with the above-mentioned characteristic edge recognition conditions. The edge length feature includes edge length and azimuth angle. As long as the edge length is less than the set width threshold, and the azimuth angles of the two edges adjacent to the edge satisfy |α1-α2-π|<θ, or α1-α2+π|<θ, the edge of the surface element is a short characteristic edge.

[0059] The width threshold can be set according to the scale of the reduction of the topographic map. For example, if a 1:2000 scale topographic map is reduced to a 1:5000 scale topographic map, the width threshold can be set to 3.5m, and if a 1:5000 scale topographic map is reduced to a 1:10000 scale topographic map, the width threshold can be set to 7m. The azimuth threshold can be set to π / 24. The edge length feature of the surface element is less than 3.5m, and satisfies |α1-α2-π|<π / 24, or |α1-α2+π|<π / 24. The edge is a short feature edge.

[0060] like Figure 2 The surface elements P1P2P3P4P5P6P7P8 shown in the figure have side lengths of side P4P5 and side P8P1 less than 3.5m, and also meet the azimuth threshold limit. Therefore, the short feature sides of the surface elements shown in the figure are side P4P5 and side P8P1. Because the number of short feature sides is 2, it meets the conditions for further dimensionality reduction processing, so it is necessary to further perform dimensionality reduction processing on the surface elements shown in the figure.

[0061] In this embodiment, optionally, determining the long feature edge of the planar element includes: dividing the boundary of the planar element into two parts by the short feature edge, and forming the long feature edge with the line segments of the two parts obtained by the division.

[0062] Specifically, we can use the short feature edges P4P5 and P8P1 to Figure 2 The boundary of the surface element shown is divided into two parts, and the line segments of the two parts are formed as follows Figure 3 The two independent long feature edges shown are P1P2P3P4 and P5P6P7P8.

[0063] In this embodiment, optionally, constructing a virtual edge between long feature edges according to the position coordinates of each node of the long feature edge includes:

[0064] Calculate the distance between each node of the long feature edge according to the corresponding position coordinates;

[0065] The distance between each node is compared with the distance threshold, and two nodes whose distance is less than the distance threshold are selected to form a virtual edge.

[0066] Specifically, when constructing virtual edges between long feature edges based on the position coordinates of each node of the long feature edge, the position coordinates of each node in the long feature edge can be obtained through the map information system, and the distance between the nodes of one long feature edge and the nodes of other long feature edges can be calculated based on the corresponding coordinates. Because the long feature edge includes the nodes of the short feature edge, the nodes corresponding to the short feature edge can be excluded when calculating the distance.

[0067] Afterwards, the calculated distance data can be compared with the distance threshold. Two nodes whose distance data is less than the distance threshold can be used as two virtual nodes of the virtual edge, thereby constructing a virtual edge between the long feature edges. In this embodiment, the distance threshold can be set to 1.5 times the width threshold.

[0068] by Figure 3 Taking the two long feature edges shown in the figure as an example, through calculation and comparison, it is found that the distance between the node P2 of the long feature edge P1P2P3P4 and the node P7 of the long feature edge P5P6P7P8, and the distance between the node P3 and the node P6 are less than the distance threshold. Node P2 and node P7 can be used as virtual nodes to construct the virtual edge P2P7, and node P3 and node P6 can be used as virtual nodes to construct the virtual edge P3P6. The virtual edge constructed between the long feature edge P1P2P3P4 and the long feature edge P5P6P7P8 is as follows Figure 4 shown.

[0069] In this embodiment, optionally, if there is a special node in the long feature edge, and the distance between the special node and the nodes of other long feature edges is greater than a distance threshold, then the position point closest to the special node in other long feature edges is selected to form a virtual edge with the special node.

[0070] In the process of calculating the node distance between long feature edges, there may be a special case where the distance between the node of the long feature edge and the nodes of other long feature edges is greater than the distance threshold, and this node is a special node. For this special node, the position coordinates of each position point on other feature edges can be traversed, and the position point closest to the special node can be selected as a virtual node to form a virtual edge with the special node.

[0071] After the virtual edges between the long feature edges are constructed, the position coordinates of the midpoints of each virtual edge can be determined based on the position coordinates of the virtual nodes of the virtual edge, and the position coordinates of the midpoints of the short feature edges can be determined based on the position coordinates of the nodes of the short feature edges. Then, the midpoints of the short feature edges and the midpoints of the virtual edges can be connected in sequence to generate line features.

[0072] like Figure 5 As shown, the midpoints of the short feature edge P8P1 and the short feature edge P4P5 are points C1 and C4 respectively, and the midpoints of the virtual edge P2P7 and the virtual edge P3P6 are C2 and C3 respectively. Connecting points C1, C2, C3 and C4 in sequence constitutes the line element C1C2C3C4 after dimensionality reduction of the surface element P1P2P3P4P5P6P7P8.

[0073] The length of the line element can be calculated based on the position coordinates of the midpoint of the short feature edge and the midpoint of the virtual edge. The length of the line element is compared with the length threshold. If the length of the line element is greater than the length threshold, the line element is directly symbolized to obtain the line element after the surface element is reduced in dimension. If the length of the line element is less than the length threshold, the midpoint of the line element is symbolized to obtain the point element after the surface element is reduced in dimension. The direction of the point element is the azimuth of the line element.

[0074] A storage medium stores a computer program, which executes the above-mentioned method for reducing the dimension of planar artificial elements when the computer program is running.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for reducing the dimension of planar artificial elements, characterized in that: include: Obtaining the element features of the surface elements in the large-scale topographic map, the element features include area features and the length features of each side; Determine whether the area element needs to be reduced in dimension based on the area feature; In response to the need to perform dimensionality reduction processing on the surface element, the edge length feature of each edge is matched with the characteristic edge recognition condition, the short characteristic edges of the surface element are screened out, and the number of the screened short characteristic edges is counted; Determine whether further dimensionality reduction is needed for the surface element based on the number of short feature edges; In response to the need for further dimensionality reduction processing, the edges of the planar elements are divided according to the short characteristic edges to determine the long characteristic edges of the planar elements; Construct virtual edges between long feature edges according to the position coordinates of each node of the long feature edge; Connect the midpoints of the short feature edges and virtual edges in sequence to generate line features; Determine whether the length of the line feature exceeds the length threshold. If the length of the line feature exceeds the length threshold, reduce the dimension of the area feature to a line feature. Otherwise, reduce the dimension of the area feature to a point feature. The step of constructing virtual edges between long feature edges according to the position coordinates of each node of the long feature edge comprises: Calculate the distance between each node of the long feature edge according to the corresponding position coordinates; Compare the distance between each node with the distance threshold, and select two nodes whose distance is less than the distance threshold to form a virtual edge; If there is a special node in the long feature edge, and the distance between the special node and the nodes of other long feature edges is greater than the distance threshold, the position point closest to the special node in other long feature edges is selected to form a virtual edge with the special node.

2. The method for dimensionality reduction of planar artificial elements according to claim 1, characterized in that: The determining whether it is necessary to perform dimensionality reduction processing on the surface element by using the area feature includes: The area feature is compared with the area threshold. If the area feature is smaller than the area threshold, the surface element needs to be processed for dimensionality reduction. Otherwise, the surface element does not need to be processed for dimensionality reduction.

3. The method for reducing the dimension of planar artificial elements according to claim 2, characterized in that: The characteristic edge recognition conditions include: ； in, is the side length, , are the azimuths of two adjacent sides, is the angle threshold, is the width threshold.

4. The method for reducing the dimension of planar artificial elements according to claim 3, characterized in that: The width threshold, the area threshold, and the length threshold are set according to the reduction scale.

5. The method for reducing the dimension of planar artificial elements according to claim 1, characterized in that: The determining of the long characteristic edge of the planar element comprises: dividing the boundary of the planar element into two parts by the short characteristic edge, and forming the long characteristic edge with line segments of the two divided parts.

6. The method for reducing the dimension of planar artificial elements according to claim 1, characterized in that: The distance threshold is 1.5 times the width threshold.

7. The method for reducing the dimension of planar artificial elements according to claim 1, characterized in that: The coordinates of the point element are the midpoint of the line element, and the direction of the point element is the azimuth of the line element.

8. A storage medium storing a computer program, characterized in that: When the computer program is running, the method for reducing the dimension of artificial surface elements as described in any one of claims 1 to 7 is executed.

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