TIN algorithm-based roadway CAD center line extraction method

Abstract

The invention discloses a roadway CAD center line extraction method based on a TIN algorithm. The method comprises the following steps of S1, extracting roadway point location original data according to roadway CAD drawing data; s2, noise points in the original data of the roadway point locations are filtered out, outlier point locations are removed, and repeated point locations are removed; s3, each point location in the roadway point location original data is connected with an associated point location, and a point location topological graph is constructed; s4, interpolating point locations among the key point locations in the point location topological graph according to a preset roadway width; s5, constructing a Delaunay triangular mesh according to the point locations in the point location topological graph, and forming a plurality of triangular surfaces; s6, deleting the abnormal triangular surface according to the preset roadway width; s7, connecting lines on the triangular surfaces according to the number of adjacent triangular surfaces of the triangular surfaces, and constructing a center line point position set; and S8, connecting the point locations in the center line point location set to obtain the roadway center line.

Description

Technical Field

[0001] This invention relates to the field of mining construction, and in particular to a method for extracting the centerline of roadways in CAD based on the TIN algorithm. Background Technology

[0002] In mining and underground engineering, the centerline of a tunnel is a core baseline for design, construction, monitoring, and BIM modeling, directly affecting support design, ventilation calculations, and transportation planning. Currently, existing centerline extraction methods are based on cross-sections. The main process involves cutting cross-sections at equal or varying intervals along the tunnel's mileage direction, extracting the geometric center of each cross-section, and finally connecting the geometric center points to form the centerline. However, this method results in severe distortion of irregular cross-sections and is prone to "inward shrinkage" or "outward drift" at bends, affecting the accuracy of the centerline. Furthermore, this method is only applicable to straight sections with regular arched tunnels and cannot quickly extract centerlines from branching or abruptly changing tunnels, limiting its applicability and requiring improvement. Summary of the Invention

[0003] The purpose of this invention is to address the above-mentioned problems by providing a simple, accurate, and efficient method for extracting the centerline of a roadway based on the TIN algorithm.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows: A method for extracting the centerline of a roadway based on the TIN algorithm includes the following steps: S1. Extract the original data of tunnel locations based on the tunnel CAD drawings; S2. Filter out noise from the original data of roadway locations, remove outlier locations, and remove duplicate locations; S3. Connect related points to each point in the original data of the roadway points to construct a point topology map; S4. Interpolate points between key points in the point topology map based on the preset roadway width; S5. Construct a Delaunay triangular mesh based on the points in the point topology map to form several triangular faces; S6. Delete abnormal triangular faces according to the preset tunnel width; S7. Connect the triangles on the triangles according to the number of adjacent triangles to construct a set of midline points; S8. Connect the points in the centerline point set to obtain the roadway centerline.

[0005] Furthermore, in step S5, when constructing the Delaunay triangular mesh, the principles of minimum triangle faces and empty circles are followed.

[0006] Furthermore, in step S6, it is determined sequentially whether any side of each triangular face is greater than twice the preset tunnel width. If so, the triangular face is determined to be an abnormal triangular face and deleted; otherwise, it is retained.

[0007] Furthermore, in step S6, after deleting the abnormal triangular face, it is determined in turn whether each triangular face has an adjacent triangular face. If they do, they are retained; if they do not, the triangular face is deleted.

[0008] Furthermore, in step S7, the number of adjacent triangular faces of each triangular face is determined sequentially. If there is one adjacent triangular face, the centroid of the triangular face is connected to the midpoint of a shared edge. If there are two adjacent triangular faces, the midpoints of the two shared edges of the triangular face are connected. If there are three adjacent triangular faces, the centroid of the triangular face is connected to the midpoints of the three shared edges.

[0009] Compared with the prior art, the advantages and positive effects of this invention are: This invention constructs a point topology map from the original point data in the tunnel CAD drawing data, then builds a Delaunay triangular mesh, deletes abnormal triangular faces, and connects the triangular faces according to the number of adjacent triangular faces to obtain a set of centerline points. Finally, connecting the points in the centerline point set yields the tunnel centerline. This method can accurately and efficiently extract the tunnel centerline from the tunnel CAD drawing data, even at irregular cross-sections and turns, without exhibiting "inward shrinkage" or "outward drift" phenomena. Furthermore, the centerline extraction method of this invention can also achieve rapid extraction in complex tunnels with multiple branches and abrupt changes, making it widely applicable and possessing greater market potential. Attached Figure Description

[0010] 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, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 A diagram showing the classification of triangle types; Figure 2 This is a topological diagram of the centerline of the tunnel. Detailed Implementation

[0012] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art to all other embodiments obtained without creative effort should be included within the protection scope of the present invention.

[0013] This embodiment discloses a method for extracting the centerline of a roadway based on the TIN algorithm. The operation steps are as follows: 1. Extract the original data of roadway points based on the provided CAD drawings of the roadways; that is, extract the roadway data points based on the mining plan provided by the mine. Here, the roadway points are the points on both sides of the roadway (composed of basic line segments in the mining plan). 2. Noise filtering is performed on the original roadway point data, outlier removal is performed, and duplicate points are removed; that is, points far away from the original point cluster area are filtered out, and duplicate points are removed (two points with a distance of less than 0.01m are judged as the same point). 3. Construct point associations for the original data of roadway points, and record the associated points for each point to build a point topology map; Since the data on both sides of the tunnel in the CAD drawing consists of line segments or multiple line segments, the original data of the CAD tunnel is extracted, and the connection relationship between the line segments is determined based on whether there are any points in common between the two line segments (two points are judged to be the same point if the distance between them is less than 0.01m), and a point topology map is established. 4. The key points in the point topology map (i.e., the connection points between line segments in the topology map) are interpolated based on the preset roadway width to densify the points. 5. Based on all the points in the densified topology map, construct a Delaunay triangular mesh, following the principles of minimum triangle and empty circle, to obtain multiple triangles; 6. Delete abnormal triangular faces according to the preset roadway width; any side of a triangular face is determined to be an abnormal triangular face if it is greater than 2 * roadway width. After deleting abnormal triangular faces, check whether the triangular face has adjacent triangular faces and delete the triangular face that has no adjacent triangular faces. 7. Divide the constructed triangles into three types based on the number of adjacent triangles (e.g., ...). Figure 1 As shown in I, II, and III), there is one adjacent triangular face (i.e. Figure 1 In section I), connect the centroid of the triangular face to the midpoint of its adjacent side; for triangles with two adjacent triangular faces (i.e. Figure 1 (II) Connect the midpoints of the two shared sides; (i.e., triangles with three adjacent faces) Figure 1 (III) Connect the centroid of the triangle to the center points of the three sides to construct the set of midline points and the relationship between the center points; 8. Connecting the center points within the set of centerline points forms the tunnel centerline; the specific operation is as follows: construct a tunnel centerline topology diagram based on the tunnel centerline points (e.g., Figure 2 As shown in the diagram, the construction steps are similar to those in step 3. In the topology diagram of the roadway centerline, if there are ≥3 associated points, the points are merged. Then, the multiple line segments formed by the points between one associated point and three associated points are smoothed by Bézier curves to obtain a smooth roadway centerline.

[0014] This invention constructs a point topology map from the original point data in the tunnel CAD drawing data, then builds a Delaunay triangular mesh, deletes abnormal triangular faces, and connects the triangular faces according to the number of adjacent triangular faces to obtain a set of centerline points. Finally, connecting the points in the centerline point set yields the tunnel centerline. This method can accurately and efficiently extract the tunnel centerline from the tunnel CAD drawing data, even at irregular cross-sections and turns, without exhibiting "inward shrinkage" or "outward drift" phenomena. Furthermore, the centerline extraction method of this invention can also achieve rapid extraction in complex tunnels with multiple branches and abrupt changes, making it widely applicable and possessing greater market potential.

Claims

1. A method for line extraction in tunnel CAD based on TIN algorithm, characterized in that: The method comprises the following steps: S1, extracting roadway point original data according to roadway CAD drawing data; S2, filtering out noise points in the roadway point original data, removing outlier points, and removing duplicate points; S3, connecting associated points at each point in the roadway point original data to construct a point topology graph; S4, interpolating points between key points in the point topology graph according to a preset roadway width; S5, constructing a Delaunay triangular grid according to the points in the point topology graph to form a plurality of triangular faces; S6, deleting abnormal triangular faces according to the preset roadway width; S7, connecting lines on the triangular faces according to the number of adjacent triangular faces to construct a centerline point set; S8, connecting points in the centerline point set to obtain a roadway centerline.

2. The method for line extraction in TIN algorithm based tunnel CAD of claim 1, wherein: In the step S5, when constructing the Delaunay triangular grid, the minimum triangular face and empty circle principle are followed.

3. The method for line extraction in tunnel CAD based on TIN algorithm according to claim 2, characterized in that: In the step S6, whether any side of each triangular face is greater than twice the preset roadway width is judged in sequence, if yes, the triangular face is determined as an abnormal triangular face and is deleted, if not, the triangular face is reserved.

4. The method for line extraction in tunnel CAD based on TIN algorithm according to claim 3, characterized in that: In the step S6, after deleting the abnormal triangular face, whether each triangular face has adjacent triangular faces is judged in sequence, if yes, the triangular face is reserved, if not, the triangular face is deleted.

5. The method for line extraction in tunnel CAD based on TIN algorithm according to claim 4, characterized in that: In the step S7, the number of adjacent triangular faces of each triangular face is judged in sequence, if the number of adjacent triangular faces is one, the center of gravity point of the triangular face and the midpoint of a shared edge are connected, if the number of adjacent triangular faces is two, the midpoints of two shared edges of the triangular face are connected, if the number of adjacent triangular faces is three, the center of gravity point of the triangular face and the midpoints of three shared edges are connected.

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