A method and system for simplifying OSM map data under-length roads

Abstract

The application discloses a kind of methods and systems for simplifying OSM map data over short road, method includes: OSM map data is converted into graph data structure;Iterate line segment set, according to the length threshold value set to find the line segment needing to be simplified, and determine its search range;Collection needs to be simplified the periphery range information of line segment, calculate the geometric difference between the geometric characteristics of line segment itself and periphery road, detect and judge whether the line segment needs to be merged;Take the midpoint of the line segment to be merged to inherit the connection between two end points and other line segments, update line segment geometric information to obtain new graph data structure.The application can automatically simplify the over short road of city scale OSM map data without actual map reference, save the manpower and time cost of repeated checking road network, help to improve the accuracy of subsequent road network analysis.

Description

Technical Field

[0001] This invention relates to the field of road traffic graphic processing technology, specifically to a method and system for simplifying excessively short roads in OSM map data. Background Technology

[0002] Traffic simulation has become an effective tool for comprehensive decision-making in urban design and transportation planning. Quickly and accurately acquiring urban road data and optimizing it into directly applicable data is of great significance. In recent years, OSM (Optical Sequence Mapping) road network data has become a commonly used dataset in transportation, planning, and other fields. Compared with other spatial geographic data, OSM has advantages such as being free, timely updated, covering a wide area, and having accurate locations. However, directly downloaded OSM data contains redundant information. In particular, excessively short roads severely affect the road network topology and simplification process, reducing the efficiency of urban road network spatial analysis. Therefore, how to provide a more convenient and efficient way to simplify redundant road network information based on downloaded OSM data deserves in-depth exploration.

[0003] Traditional methods of manually verifying OSM road network data can obtain relatively accurate road information, but manual verification is tedious and time-consuming, especially at the urban scale, where its feasibility and accuracy are greatly reduced. With the continuous development of deep learning technology, it has become possible to automatically simplify OSM map data through programming. This invention patent specifically solves the problem of simplifying excessively short roads through a graph distribution algorithm. Summary of the Invention

[0004] Purpose of the invention: To address the above-mentioned technical problems, the purpose of this invention is to provide a method and system for simplifying OSM map data with excessively short roads, saving manpower and time costs associated with repeated road network verification, and helping to improve the accuracy of subsequent road network analysis.

[0005] Technical Solution: To achieve the above-mentioned objectives, this invention provides a method for simplifying excessively short roads in OSM map data, comprising the following steps:

[0006] The OSM map data is transformed into a graph data structure; the graph data treats each intersection as a node and each road segment as a line segment, and stores the line segments connected to each node, the nodes connected to each line segment, the spatial coordinate information of the nodes, and the spatial path information of the line segments.

[0007] Iterate through the set of line segments E, and find the line segments e that need to be simplified based on the set length threshold. i And determine its search scope;

[0008] set e i Surrounding area information, calculate e i Detect the geometric differences between the line segment itself and the surrounding roads, and determine whether the line segment needs to be merged.

[0009] Take the midpoint of the line segment to be merged and inherit the connection relationship between the two endpoints of the original line segment and other line segments;

[0010] Update the geometric information of the line segments and modify the connection relationships to obtain a new graph data structure.

[0011] Furthermore, the step of converting OSM map data into a graph data structure, S1, specifically includes:

[0012] The topological structure of the urban road network in the OSM map data is described by a graph data G, where G = (N, E), N = (Nid, VN, FN), and E = (Eid, VE, FE). Each intersection is considered a node, and all nodes are denoted as a set N, where n1, n2, ..., n m ∈N; each road segment is considered as a line segment, and all line segments are denoted as set E, where e1, e2, ..., e q ∈E. Where Nid and Eid represent unique codes for each node and line segment, used to retrieve information from their corresponding VN, FN, VE, and FE. V represents the graph's connectivity, and VN stores the connectivity between node n and line segment e, which can be represented as n i ={e j1 ,e j2 ,…}(i≤m;j1,j2≤q); VE stores the connection relationship between line segment e and node n, which can be represented as e i ={n j1 ,n j2 ,…}(i≤q;j1,j2≤m). F represents spatial information, FN stores the spatial coordinate information of nodes, and FE stores the spatial path of line segments, including length, coordinates of intermediate points of the path, etc.

[0013] Furthermore, the process involves traversing the set of line segments E and, based on a set length threshold, finding the line segment e that needs simplification. i And determine its search scope, specifically including:

[0014] Iterate through the set of line segments E, find all line segments with a length less than the threshold α, and denote them as the line segments e that need to be simplified. i .

[0015] With e i Starting from point t, search for all line segments within t neighborhoods (t degrees) and store them in set B.

[0016] Furthermore, the set e i Surrounding area information, calculate e i The geometric features of the line segment itself and the geometric differences between the surrounding roads are used to detect and determine whether the line segment needs to be merged. Specifically, this includes:

[0017] Let R be the value used to determine line segment e. i Whether an indicator needs to be merged can effectively help determine e. i Does it need to be merged? Where δ is a hyperparameter, e b e i Line segments within t degrees (e) b ∈B), len(B) represents the relationship with e i The number of line segments within degree t, L eb For line segment e b The length of the line segment. Through multiple experiments, it has been found that when δ = 4, the effect of determining whether line segments need to be merged is optimal. If line segment e... i Length L ei If <R, then mark the line segment as the line segment to be merged, e. i .

[0018] Furthermore, the step of taking the midpoint of the line segment to be merged, which inherits the connection relationship between the two endpoints of the original line segment and other line segments, specifically includes:

[0019] Take the line segment e to be merged i The midpoint p of the original line segment inherits the connection relationships between the two endpoints of the original line segment and other line segments. Let the original line segment e be denoted as e. i The endpoints are a and b, and the line segment e is... i The line segment connecting point b is denoted as e. i’ line segment e i’ The other endpoint is denoted as point c. If Then move the endpoint b of the line segment to point p; if Then move point b back a distance Ф to line segment e. i’ At point b', connect point b' to point p. Through multiple experiments, it is known that the value of Ф is related to the line segment e. i’ The distance from point b is related to the nearest geometric point d, when Ф=γ*L bd When the line segment fits best, L bd Let be the length between points b and d, and β and γ be preset thresholds.

[0020] Furthermore, step S5 updates the geometric information of the line segments and modifies the connection relationships to obtain a new graph data structure, specifically including:

[0021] Delete line segment e from set E. i Remove points a and b from set N, add point p, and update sets VN, VE, FN, and FE to obtain a new graph data structure.

[0022] Based on the same inventive concept, this invention provides a system for simplifying excessively short roads in OSM map data, comprising:

[0023] The data conversion module is used to convert OSM map data into a graph data structure. The graph data treats each intersection as a node and each road segment as a line segment, storing the line segments connected to each node, the nodes connected to each line segment, the spatial coordinate information of the nodes, and the spatial path information of the line segments.

[0024] The line segment merging judgment module is used to traverse the line segment set E and find the line segment e that needs to be simplified based on the set length threshold. i and determine its search scope; set e i Surrounding area information, calculate e i Detect the geometric differences between the line segment itself and the surrounding roads, and determine whether the line segment needs to be merged.

[0025] The line segment merging module is used to extract the midpoint of the line segment to be merged, inherit the connection relationship between the two endpoints of the original line segment and other line segments, update the geometric information of the line segment and modify the connection relationship to obtain a new graph data structure.

[0026] Based on the same inventive concept, the present invention provides a computer system including a memory, a processor, and a computer program / instructions stored in the memory and executable on the processor, wherein the computer program / instructions, when executed by the processor, implement the steps of the method for simplifying OSM map data for short roads.

[0027] Based on the same inventive concept, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method for simplifying OSM map data for too short roads.

[0028] Based on the same inventive concept, the present invention provides a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the method for simplifying OSM map data for excessively short roads.

[0029] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0030] 1. This method can automatically delete excessively short lines in road network data, eliminating the time cost of manual verification.

[0031] 2. This invention can automatically generate a simplified urban road network with short lines by downloading open-source OSM map data and following the method flow, without referring to real-world image maps and without being constrained by other functions.

[0032] 3. The road network generated by the method of this invention retains the original road attribute information, does not destroy the integrity of the entire road network, and has high accuracy. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a flowchart of the overall method of the present invention;

[0035] Figure 2 This is a partial road network diagram of an example of the present invention;

[0036] Figure 3 This is a schematic diagram of step 4. The midpoint of the line segment to be merged is denoted as p.

[0037] Figure 4 This is a schematic diagram of step 4, calculating the line segment difference;

[0038] Figure 5 This is a diagram from step 5, updating line segments, nodes, and their connections;

[0039] Figure 6 This is a comparison diagram of the simplified road network (a) and the OSM road network (b) processed by OSMNX according to the method of this invention. Detailed Implementation

[0040] The technical solutions provided by the present invention will be described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0041] This invention uses the urban road network of a certain city as an example for illustration. The map of this area in OpenStreetMap is as follows: Figure 2 As shown in the figure. This invention provides a method for simplifying excessively short roads in OSM map data, the process of which is as follows: Figure 1 As shown, the specific steps include:

[0042] Step 1: Download OSM map data for the specified area and convert it into a graph data structure. This includes:

[0043] Step 11: Use the OSM map API interface to download and store the OSM map data within the specified area.

[0044] Step 12: Describe the topology of the urban road network in the OSM map data by defining graph data G, where G = (N, E), N = (Nid, VN, FN), and E = (Eid, VE, FE). Treat each intersection as a node, and denote all nodes as a set N, where n1, n2, ..., n m∈N; each road segment is considered as a line segment, and all line segments are denoted as set E, where e1, e2, ..., e q ∈E. Where Nid and Eid represent unique codes for each node and line segment, used to retrieve information from their corresponding VN, FN, VE, and FE. V represents the graph's connectivity, and VN stores the connectivity between node n and line segment e, which can be represented as n i ={e j1 ,e j2 ,…}(i≤m;j1,j2≤q); VE stores the connection relationship between line segment e and node n, which can be represented as e i ={n j1 ,n j2 ,…}(i≤q;j1,j2≤m). F represents spatial information, FN stores the spatial coordinate information of nodes, and FE stores the spatial path of line segments, including length, coordinates of intermediate points of the path, etc.

[0045] Step 2: Traverse the line segment set E and find the line segment e that needs to be simplified based on the set length threshold. i And determine its search scope. Specifically, this includes:

[0046] Step 21: Traverse the set of line segments E and find all line segments whose length is less than the threshold α, denoted as the line segment e that needs to be simplified. i After multiple experiments, the optimal line segment was selected when α = 50.

[0047] Step 22, with e i Starting from point t, search for all line segments within t neighborhoods (t degrees) and store them in set B. After multiple experiments, considering model performance and computational cost, t=2 is the optimal value.

[0048] In this embodiment, a line segment e with a length of less than 50 meters is used. 153 Let's take an example and explain in detail. Searching for all line segments within 2 degrees is equivalent to finding e. 145 e 146 e 147 e 148 e 149 e 150 e 151 e 152 e 154 e 155 e 157 e 158 e 159 e 161 e 162 There are 15 line segments in total, which are stored in set B.

[0049] Step 3, set e i Surrounding area information, calculate e iThe geometric features of the line segment itself and the geometric differences between it and the surrounding roads are used to detect and determine whether the line segment needs to be merged. Specifically, R is set as the criterion for merging line segment e. i Whether an indicator needs to be merged can effectively help determine e. i Does it need to be merged? Where δ is a hyperparameter, e b For e i Line segments within t degrees (e) b ∈B), len(B) represents e i The number of line segments within degree t, L eb To call line segment e b The length of the line segment in the corresponding FE set. Multiple experiments have shown that δ = 4 is the most effective way to determine whether line segments need to be merged. If L... ei If <R, then mark the line segment as the line segment to be merged, e. i .

[0050] In this embodiment, e i There are 15 line segments within degree t, so len(B) = 15. Length measurement shows that e 147 =96m,e 148 =97m, e 152 =137m, e 154 =178m, e 149 =11m,e 150 =12m, e 145 =121m,e 146 =121m,e 151 =154m, e 155 =153m, e 161 =85m, e 162 =86m, e 157 =140m, e 159 =139m, e 158 =8m. Calculations show that L in this embodiment... eb =1538. When δ=4, R=25.63. In this embodiment, L ei =8m, L ei <R, so mark e i These are the line segments to be merged.

[0051] Step 4, select the line segment e to be merged. i The midpoint p of the original line segment inherits the connection relationships between the two endpoints of the original line segment and other line segments. Let the original line segment e be denoted as e. i The endpoints are a and b, and the line segment e is... i The line segment connecting point b is denoted as e. i’ line segment e i’ The other endpoint is denoted as point c. If Then move the endpoint b of the line segment to point p; if Then move point b back a distance Ф to line segment e. i’ At point b', connect point b' to point p. Through multiple experiments, it is known that the value of Ф is related to the line segment e. i’ The distance from point b is related to the nearest geometric point d, when Ф=γ*L bd When β = 20 and γ = 1 / 10, the line segment fits best. Generally, the model fits best when β = 20 and γ = 1 / 10.

[0052] In this embodiment, the line segment e to be merged is taken as... 153 The midpoint is denoted as p, inheriting the connection relationships between the two endpoints of the original line segment and other line segments. In step 4, a, b, and c correspond to N in this example. 457 N 458 N 463 In this embodiment, That is, line segment N 464 N 458 With line segment N 464 The difference in length of p, i.e. The endpoint N of the line segment 458 Move to point p. After multiple iterations of calculation, simplify line segment e. i .

[0053] Step 5: Update the geometric information of the line segments and modify the connection relationships to finally obtain the new graph data structure. In this embodiment, line segment e is deleted from set E. 153 Remove node N from set N 457 N 458 Add point p. Simultaneously update sets VN, VE, FN, and FE to obtain a new graph data structure.

[0054] To verify the effectiveness of this invention, the OSM road network processed by OSMNX was compared with the simplified road network of this solution. Figure 6 As shown in the illustration. Implementation examples demonstrate that the method of this invention can automatically delete excessively short lines in road network data, eliminating the time cost of manual verification. Furthermore, the road network retains its original road attribute information, without compromising the integrity of the entire road network, and exhibits high accuracy.

[0055] Based on the same inventive concept, embodiments of the present invention provide a system for simplifying excessively short roads in OSM map data, comprising: a data conversion module for converting OSM map data into a graph data structure; and a line segment merging judgment module for traversing a set of line segments E and finding the line segments e that need to be simplified according to a set length threshold. i and determine its search scope; set e i Surrounding area information, calculate e iThe system detects the geometric differences between the line segment itself and the surrounding roads, and determines whether the line segment needs to be merged. The line segment merging module is used to take the midpoint of the line segment to be merged and inherit the connection relationship between the two endpoints of the original line segment and other line segments. The system updates the geometric information of the line segment and modifies the connection relationship to obtain a new graph data structure.

[0056] Based on the same inventive concept, embodiments of the present invention provide a computer system, including a memory, a processor, and a computer program / instructions stored in the memory and executable on the processor, wherein the computer program / instructions, when executed by the processor, implement the steps of the method for simplifying OSM map data for too short roads.

[0057] Based on the same inventive concept, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method for simplifying OSM map data for excessively short roads.

[0058] Based on the same inventive concept, embodiments of the present invention provide a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the method for simplifying OSM map data with excessively short roads.

Claims

1. A method for simplifying excessively short roads in OSM map data, characterized in that, Includes the following steps: The OSM map data is transformed into a graph data structure; the graph data treats each intersection as a node and each road segment as a line segment, and stores the line segments connected to each node, the nodes connected to each line segment, the spatial coordinate information of the nodes, and the spatial path information of the line segments. Iterate through the set of line segments E, and find the line segments e that need to be simplified based on the set length threshold. i And determine its search scope; set e i Surrounding area information, calculate e i Detect the geometric differences between the line segment itself and the surrounding roads, and determine whether the line segment needs to be merged. Take the midpoint of the line segment to be merged and inherit the connection relationship between the two endpoints of the original line segment and other line segments; Update the geometric information of the line segments and modify the connection relationships to obtain a new graph data structure; The process of converting OSM map data into a graph data structure specifically includes: Define graph data G to describe the topology of the urban road network in OSM map data, where G=(N,E), N=(Nid,VN,FN), E=(Eid,VE,FE); treat each intersection as a node, and denote all nodes as a set N, where n1, n2, ..., n m ∈N, m is the number of nodes; each road segment is considered as a line segment, and all line segments are denoted as set E, where e1, e2, ..., e q ∈E, where q is the number of line segments; where Nid and Eid represent unique codes for each node and line segment, used to retrieve information from their corresponding VN, FN, VE, FE; V represents the connection relationship of the graph, and VN stores the connection relationship between node n and line segment e, represented as n i ={e j1 ,e j2 ...}, i≤m;j1,j2≤q;VE stores the connection relationship between line segment e and node n, represented as e i ={n j1 ,n j2 ...}, i≤q;j1,j2≤m; F represents spatial information, FN stores the spatial coordinate information of nodes, and FE stores the spatial path of line segments, including length and coordinates of intermediate points of the path; The process of taking the midpoint of the line segment to be merged, inheriting the connection relationship between the two endpoints of the original line segment and other line segments, specifically includes: Take the line segment e to be merged i The midpoint p of the original line segment inherits the connection relationships between the two endpoints of the original line segment and other line segments. Let the original line segment e be denoted as e. i The endpoints are a and b, and the line segment e is... i The line segment connecting point b is denoted as e. i’ line segment e i’ The other endpoint is denoted as point c; if || - If || < β, then move the endpoint b of the line segment to point p; if || - If ||≥β, then move point b back a distance Ф to line segment e. i’ At point b', connect point b' to point p, and take the value of Ф and line segment e. i’ The distance from point b is related to the geometric point d closest to point b, when Ф=γ×L bd When the line segment fits the best, L... bd Let be the length between points b and d, and β and γ be preset thresholds.

2. The method for simplifying excessively short roads in OSM map data according to claim 1, characterized in that, The line segment set E is traversed, and the line segment e that needs to be simplified is found according to the set length threshold. i And determine its search scope, specifically including: Iterate through the set of line segments E, find all line segments with a length less than the threshold α, and denote them as the line segments e that need to be simplified. i ; With e i Starting from t, search for all line segments within t neighborhoods and store them in set B.

3. The method for simplifying excessively short roads in OSM map data according to claim 1, characterized in that, The set e i Surrounding area information, calculate e i The geometric features of the line segment itself and the geometric differences between the surrounding roads are used to detect and determine whether the line segment needs to be merged. Specifically, this includes: Set R as the index for judging whether the line segment e i needs to be merged. R = , where δ is a hyperparameter, and e b is the line segment within t degrees of e i . e b ∈B, and len(B) represents the number of line segments within t degrees of e i . L eb is the length of the line segment e b . If the length L i of the line segment e ei < R, then mark this line segment as the line segment e i to be merged.

4. The method for simplifying excessively short roads in OSM map data according to claim 1, characterized in that, The process of updating the geometric information of line segments and modifying the connection relationships to obtain a new graph data structure specifically includes: Delete line segment e from the set of line segments E. i Delete line segment e from node set N i Add line segment e to the nodes a and b corresponding to the two endpoints. i The midpoint p is determined, and the set of line segments connected to the relevant nodes VN, the set of nodes connected to the line segments VE, the spatial coordinate information of the nodes FN, and the spatial path information of the line segments FE are updated simultaneously to obtain a new graph data structure.

5. A system for simplifying excessively short roads in OSM map data, characterized in that, include: The data conversion module is used to convert OSM map data into a graph data structure. The graph data treats each intersection as a node and each road segment as a line segment, and stores the line segments connected to each node, the nodes connected to each line segment, the spatial coordinate information of the nodes, and the spatial path information of the line segments. The line segment merging judgment module is used to traverse the line segment set E and find the line segment e that needs to be simplified based on the set length threshold. i and determine its search scope; set e i Surrounding area information, calculate e i Detect the geometric differences between the line segment itself and the surrounding roads, and determine whether the line segment needs to be merged. The line segment merging module is used to extract the midpoint of the line segment to be merged and inherit the connection relationship between the two endpoints of the original line segment and other line segments. Update the geometric information of the line segments and modify the connection relationships to obtain a new graph data structure; The process of converting OSM map data into a graph data structure specifically includes: Define graph data G to describe the topology of the urban road network in OSM map data, where G=(N,E), N=(Nid,VN,FN), E=(Eid,VE,FE); treat each intersection as a node, and denote all nodes as a set N, where n1, n2, ..., n m ∈N, m is the number of nodes; each road segment is considered as a line segment, and all line segments are denoted as set E, where e1, e2, ..., e q ∈E, where q is the number of line segments; where Nid and Eid represent unique codes for each node and line segment, used to retrieve information from their corresponding VN, FN, VE, FE; V represents the connection relationship of the graph, and VN stores the connection relationship between node n and line segment e, represented as n i ={e j1 ,e j2 ...}, i≤m;j1,j2≤q;VE stores the connection relationship between line segment e and node n, represented as e i ={n j1 ,n j2 ...}, i≤q;j1,j2≤m; F represents spatial information, FN stores the spatial coordinate information of nodes, and FE stores the spatial path of line segments, including length and coordinates of intermediate points of the path; The process of taking the midpoint of the line segment to be merged, inheriting the connection relationship between the two endpoints of the original line segment and other line segments, specifically includes: Take the line segment e to be merged i The midpoint p of the original line segment inherits the connection relationships between the two endpoints of the original line segment and other line segments. Let the original line segment e be denoted as e. i The endpoints are a and b, and the line segment e is... i The line segment connecting point b is denoted as e. i’ line segment e i’ The other endpoint is denoted as point c; if || - If || < β, then move the endpoint b of the line segment to point p; if || - If ||≥β, then move point b back a distance Ф to line segment e. i’ At point b', connect point b' to point p, and take the value of Ф and line segment e. i’ The distance from point b is related to the geometric point d closest to point b, when Ф=γ×L bd When the line segment fits the best, L... bd Let be the length between points b and d, and β and γ be preset thresholds.

6. A computer system comprising a memory, a processor, and computer programs / instructions stored in the memory and executable on the processor, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method for simplifying short roads in OSM map data according to any one of claims 1-4.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method for simplifying short roads in OSM map data according to any one of claims 1-4.

8. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method for simplifying short roads in OSM map data according to any one of claims 1-4.

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