A method of acquiring a power line profile

Abstract

The application provides a method for obtaining a power line section view. The method comprises: obtaining point cloud data along a power line; cutting the point cloud between adjacent power towers to obtain a point cloud set D between the adjacent power towers; establishing a vertical projection plane of the center line of the power line between the adjacent power towers, projecting the points in the point cloud set D onto the vertical projection plane to obtain a point cloud projection set E; performing polyline fitting on the points in the point cloud projection set E, and inversely calculating the nodes in the polyline to obtain the three-dimensional coordinates of the corresponding elevation feature points of the nodes; and obtaining the power line section view according to the elevation feature points. The method performs polyline fitting on the points on the vertical projection plane, can improve the fitting accuracy of the real terrain, extracts the elevation feature points according to the polyline fitted according to the real terrain, greatly reduces the number of redundant elevation points without losing the accuracy of the terrain, and is suitable for obtaining the power line section view of a non-fixed step distance.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission line survey and design, and in particular to a method for obtaining a cross-sectional view of a power line. Background Art

[0002] In the existing technology, most methods for automatically extracting longitudinal section drawings of power lines use a fixed step size to extract section elevation points in DEM (digital elevation model) data. This method has the following defects: on the one hand, the DEM production process is relatively complicated, and the process requires a lot of manpower and time. In addition, the accuracy of the DEM data produced is lower than that of the original laser point cloud data, and part of the real terrain will be lost. On the other hand, the centerline section and left and right side section automatically extracted using a fixed step size will have a large number of redundant points no matter how long the step size is. If the step size is too long, the front and back sections of the mountain where the tower is located will be distorted. The steeper the terrain, the more distorted it is, and the sag tension will be distorted, affecting the design accuracy. If the step size is too small, there will be too much redundant data that designers do not need to refer to, resulting in too large a cross-section file, which is difficult to open with the design software and time-consuming and labor-intensive manual editing in the later stage.

[0003] In summary, there is an urgent need for a method for obtaining a cross-sectional diagram of a power line to solve the problems existing in the prior art. Summary of the Invention

[0004] The present invention aims to provide a method for obtaining a cross-sectional diagram of a power line, so as to solve the problems of a complex extraction process and a large amount of redundant data in the existing power line cross-sectional diagram extraction process.

[0005] To achieve the above object, the present invention provides a method for obtaining a cross-sectional view of a power line, comprising the following steps:

[0006] Step 1: Obtain point cloud data along the power line;

[0007] Step 2: Crop the point clouds between adjacent power towers to obtain the point cloud set D between adjacent power towers;

[0008] Step 3: Establish a vertical projection plane passing through the centerline of the power line between adjacent power towers, and project the points in the point cloud set D onto the vertical projection plane to obtain the point cloud projection set E;

[0009] Step 4: Perform polyline fitting on the points in the point cloud projection set E, perform inverse calculation on the nodes in the polyline, and obtain the three-dimensional coordinates of the elevation feature points corresponding to each node;

[0010] Step 5: Obtain the cross-section diagram of the power line based on each elevation feature point.

[0011] Preferably, in step one, point cloud data along the power line is acquired by an airborne laser radar, and the point cloud data is cropped and filtered for denoising.

[0012] Preferably, in the step 2, the center line of the power line is used as the center line, and the point cloud is cropped vertically with a spacing W on both sides of the center line to obtain a three-dimensional point cloud set D of strip-shaped point clouds.

[0013] Preferably, when the voltage level of the power tower is below 500kV, 10 meters ≤ W ≤ 15 meters; when the voltage level of the power tower is greater than 500kV, W ≥ 25 meters.

[0014] Preferably, in step three, the connection line between adjacent power towers forms a direction vector, and the plane determined by the direction vector and the gravity vector is the vertical projection plane.

[0015] Preferably, in step 3, the i-th point in the point cloud set D is projected by expression 1):

[0016] p i =MP i 1);

[0017] Among them, P i is the three-dimensional coordinate of the i-th point in the point cloud set D, p i The two-dimensional coordinates of the point are obtained by projecting the point in the vertical projection plane, and M is the projection matrix.

[0018] Preferably, in step 4, the points in the point cloud projection set E are fitted by an optimal curve reconstruction algorithm, and the optimal transmission distance d in the optimal curve reconstruction algorithm is determined by expression 2):

[0019]

[0020] Among them, θ is the thickness of the ground point cloud, and ρ is the point density of the point cloud.

[0021] Preferably, in step 4, the nodes in the broken line are inversely calculated using the inverse matrix of the projection matrix M.

[0022] Preferably, in step five, the centerline longitudinal section and step size are obtained based on the three-dimensional coordinates of each elevation feature point, and the centerline of the power line is offset and copied according to the edge line distance in the plan view to obtain the left and right edge lines and the corresponding plane coordinates of the elevation points on the left and right edge lines.

[0023] Preferably, in step five, based on the plane coordinates of the elevation points corresponding to the left and right edge lines, the point cloud data within the radius of the elevation point area is searched, and a triangulated network is constructed for the data within the range to obtain a local TIN, and the elevation of the plane coordinate position of the elevation point in the triangulated network is calculated, thereby obtaining the elevation points of the cross-sectional view of the left and right edge lines.

[0024] The application of the technical solution of the present invention has the following beneficial effects:

[0025] (1) In the present invention, by acquiring point cloud data along the power line, cropping it, and filtering and denoising it, the amount of data can be greatly reduced; a vertical projection plane is established between adjacent power towers, the cropped strip point cloud is projected onto the vertical projection plane, and the points on the vertical projection plane are fitted with a broken line, which can improve the fitting precision of the real terrain. Elevation feature points are directly extracted based on the broken line fitted to the real terrain. Without losing the accuracy of the terrain, the number of redundant elevation points is greatly reduced, and it is suitable for obtaining cross-sectional diagrams of power lines with non-fixed step distances. In addition, in this application, there is no need to carry out the complicated production process of DEM, and there is no need to extract elevation points with a fixed step distance, which reduces the time of internal production.

[0026] (2) In the present invention, large-area, high-precision ground point cloud data and high-resolution digital images can be quickly acquired through the airborne laser radar, high-quality point cloud data can be acquired, and three-dimensional spatial information with high temporal and spatial resolution can be quickly acquired, which is convenient for acquiring high-quality point clouds when performing the optimal curve reconstruction algorithm operation, thereby obtaining a shorter optimal transmission distance and improving the fitting precision of the broken line to complex terrain.

[0027] (3) In the present invention, by cropping the point cloud twice, the amount of point cloud data processing in the cross-sectional view acquisition process can be reduced. At the same time, by setting a reasonable spacing W, it can be ensured that the left and right edge areas in the design scheme are included in the cropped point cloud range.

[0028] (4) In the present invention, the laser radar point cloud data is used to automatically generate a power line cross-section diagram that can reflect the topography and take into account the terrain characteristics without producing a DEM, thereby reducing the redundancy of the cross-section diagram, improving the accuracy of the cross-section diagram, and better guiding the construction of power facilities, thereby improving the economic benefits of transmission line construction and the quality of engineering design.

[0029] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 This is a flow chart of a method for obtaining a cross-sectional view of a power line in an embodiment of the present application;

[0032] Figure 2 Schematic diagram of performing line fitting through a point cloud projection set in an embodiment of the present application;

[0033] Figure 3 is a power line cross-section diagram obtained in the embodiment of the present application. DETAILED DESCRIPTION

[0034] Embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered by the claims.

[0035] Embodiments:

[0036] Referring to Figures 1 to 3 A method for obtaining a power line cross-section diagram, the embodiment is applied to site selection survey of a power line.

[0037] A method for obtaining a power line cross-section diagram, referring to Figure 1 , comprising the following steps:

[0038] Step one: obtaining point cloud data along the power line;

[0039] Step 1.1: obtaining point cloud data along the power line by an airborne laser radar, the airborne laser radar technology is an active three-dimensional ground observation technology, which integrates laser ranging technology, aerial photogrammetry technology, high dynamic carrier attitude determination technology and high-precision dynamic GNSS differential positioning technology, and can quickly obtain large-area, high-precision ground point cloud data and high-resolution digital images; in the design of transmission line survey, the line often passes through regions with large height difference, dense vegetation and complex terrain, and since the airborne laser radar technology can penetrate trees to reach the ground to a certain extent, it can obtain high-quality point cloud data and quickly obtain high-spatial and temporal resolution three-dimensional spatial information. An octree index is constructed to support loading of massive laser point cloud data.

[0040] Step 1.2: cutting the point cloud data to remove point clouds obviously located outside the power corridor, obtaining power corridor point clouds, and then removing noise points and ground filtering the point cloud data, and classifying the point cloud to obtain ground laser point cloud data.

[0041] Step two: cutting the point cloud between adjacent power towers to obtain a point cloud set D between adjacent power towers;

[0042] Taking the center line of the power line in the transmission line design scheme as the center line and taking the two adjacent power towers as the end points, the point cloud is cut by a vertical plane with a spacing W on both sides of the center line to obtain a three-dimensional point cloud set D of long strip-shaped point clouds between every two power towers.

[0043] Wherein, the distance W is the cutting distance from the center line to the left and right sides, when the voltage level of the power tower is below 500kV, 10m≤W≤15m; when the voltage level of the power tower is greater than 500kV, W≥25m, so that the left and right edge areas in the design scheme are contained in the point cloud range obtained by cutting. Specifically, when the voltage level of the power tower is 35kV, 110kV or 220kV, W is 10m; when the voltage level of the power tower is 330kV or 500kV, W is 15m; when the voltage level of the power tower is greater than 500kV, W is generally 25m.

[0044] Step three: a vertical projection plane is established through the center line of the power line between adjacent power towers, and the points in the point cloud set D are projected onto the vertical projection plane to obtain a point cloud projection set E;

[0045] Step 3.1: one of the adjacent power towers is taken as the starting power tower A and the other as the ending power tower B, and the connecting line between the adjacent power towers forms a direction vector The plane determined by the direction vector and the gravity vector is the vertical projection plane, and the center line of the power line coincides with the vertical projection plane.

[0046] Step 3.2: the points in the three-dimensional point cloud set D are projected onto the vertical projection plane to obtain a two-dimensional point cloud projection set E, and the i-th point in the point cloud set D is projected by expression 1) to obtain a two-dimensional point cloud projection set E:

[0047] p i =MP i 1);

[0048] Wherein, P i (X i , Y i , Z i ) is the three-dimensional coordinates of the i-th point in the point cloud set D; p i (x i , y i ) is the two-dimensional coordinates of the point projected in the vertical projection plane, which is arranged into the two-dimensional point cloud projection set E; M is the projection matrix.

[0049] Step four: the polyline fitting is performed on the points in the point cloud projection set E, and the three-dimensional coordinates of the elevation feature points corresponding to the nodes in the polyline are obtained by back calculation;

[0050] Step 4.1: the points in the point cloud projection set E are fitted by the optimal curve reconstruction algorithm (Optimal Transportation Curve Reconstruction) in the geometric algorithm library (Computational Geometry Algorithms Library, CGAL).

[0051] In order to reflect complex terrain, it is necessary to obtain high-quality point clouds through airborne laser radar. High-quality point clouds mean lower ground point cloud thickness and higher point cloud density. The optimal transmission distance d in the optimal curve reconstruction algorithm is determined by expression 2):

[0052]

[0053] Among them, θ is the thickness of the ground point cloud (in meters), and ρ is the point cloud density (in points / square meter). A shorter optimal transmission distance d (in meters) can be obtained through high-quality point clouds, which can improve the fitting precision of the polyline to complex terrain.

[0054] When the point cloud quality is low, the ground point cloud is thicker and the point cloud density is lower, resulting in a longer optimal transmission distance d, reduced precision of the polyline fitting, inability to reflect complex terrain, and the real terrain being fuzzily simplified.

[0055] Step 4.2: Figure 2 It is an excerpt of the polyline obtained after point cloud fitting, where the nodes in the polyline are the projection points of each elevation feature point in the vertical projection plane. The nodes in the polyline are inversely calculated through the inverse matrix of the projection matrix M to obtain the three-dimensional coordinates of each elevation feature point.

[0056] P j =M -1 p j 3);

[0057] Among them, P j is the three-dimensional coordinate of the elevation feature point corresponding to the j-th node in the point cloud set D, p j is the two-dimensional coordinate of the jth node in the polyline in the vertical projection plane, M -1 is the inverse matrix of the projection matrix M.

[0058] Step 5: Obtain the cross-section diagram of the power line based on each elevation feature point.

[0059] Step 5.1: Determine the longitudinal section and step distance of the power line centerline based on the three-dimensional coordinates of each elevation feature point obtained in step 4. In the plan view, offset and copy the power line centerline according to the edge line distance to obtain the left and right edge lines. Using the coordinates corresponding to the nodes in step 4, draw a perpendicular line to the point corresponding to each node in the plan view and intersect it with the left and right edge lines to obtain the plane coordinates of the corresponding elevation points on the left and right edge lines.

[0060] Step 5.2: Based on the plane coordinates of the elevation points corresponding to the left and right edge lines, search for point cloud data within the radius of the elevation point area, and construct a triangulated network for the data within this range to obtain a local TIN (surface data structure). Calculate the elevation of the plane coordinate position of the elevation point in the triangulated network, and thus obtain the elevation points of the cross-section of the left and right edge lines.

[0061] Step 5.3: Check and verify the power line cross-section diagram and input the attributes. The obtained power line cross-section diagram is as follows: Figure 3 shown.

[0062] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for obtaining a cross-sectional view of a power line, characterized in that: The following steps are involved: Step 1: Obtain point cloud data along the power line; Step 2: Crop the point clouds between adjacent power towers to obtain the point cloud set D between adjacent power towers; Step 3: Establish a vertical projection plane passing through the centerline of the power line between adjacent power towers, and project the points in the point cloud set D onto the vertical projection plane to obtain the point cloud projection set E; Step 4: Perform polyline fitting on the points in the point cloud projection set E, perform inverse calculation on the nodes in the polyline, and obtain the three-dimensional coordinates of the elevation feature points corresponding to each node; Step 5: Obtain the cross-section of the power line according to each elevation feature point; In step 4, the points in the point cloud projection set E are fitted using the optimal curve reconstruction algorithm. The optimal transmission distance d in the optimal curve reconstruction algorithm is determined by expression 2): Among them, θ is the thickness of the ground point cloud, ρ is the point density of the point cloud; In step 5, the centerline longitudinal section and step distance are obtained according to the three-dimensional coordinates of each elevation feature point, and the centerline of the power line is offset and copied according to the sideline distance in the plan view to obtain the left and right sidelines and the plane coordinates of the corresponding elevation points on the left and right sidelines; According to the plane coordinates of the corresponding elevation points on the left and right side lines, search for point cloud data within the radius of the elevation point area, and construct a triangulated network for the data within this range to obtain a local TIN. Calculate the elevation of the plane coordinate position of the elevation point in the triangulated network, and thus obtain the elevation points of the cross-section of the left and right side lines.

2. The method for obtaining a cross-sectional view of a power line according to claim 1, wherein: In the step 1, point cloud data along the power line is acquired by airborne laser radar, and the point cloud data is cropped and filtered to remove noise.

3. The method for obtaining a cross-sectional view of a power line according to claim 1, wherein: In the second step, the point cloud is cropped with the center line of the power line as the center line and the vertical planes with a spacing W on both sides of the center line to obtain a three-dimensional point cloud set D of strip point clouds.

4. The method for obtaining a cross-sectional view of a power line according to claim 3, wherein: When the voltage level of the power tower is below 500kV, 10 meters ≤ W ≤ 15 meters; when the voltage level of the power tower is greater than 500kV, W ≥ 25 meters.

5. The method for obtaining a cross-sectional view of a power line according to claim 1, wherein: In the step three, the lines connecting the adjacent power towers form a direction vector, and the plane determined by the direction vector and the gravity vector is the vertical projection plane.

6. The method for obtaining a cross-sectional view of a power line according to claim 1, wherein: In step 3, the i-th point in the point cloud set D is projected using expression 1): p i =MP i 1); Among them, P i is the three-dimensional coordinate of the i-th point in the point cloud set D, p i The two-dimensional coordinates of the point are obtained by projecting the point in the vertical projection plane, and M is the projection matrix.

7. The method for obtaining a cross-sectional view of a power line according to claim 6, wherein: In the step 4, the nodes in the polyline are inversely calculated using the inverse matrix of the projection matrix M.

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