A DLG road elevation point updating method and system based on vehicle-mounted point cloud

Abstract

The application provides a DLG road elevation point updating method and system based on a vehicle-mounted point cloud, wherein the method comprises the following steps: superimposing a laser point cloud and road terrain map elevation points to obtain a first terrain map; determining ground laser points in a target range of the first terrain map elevation points; determining a difference value between the elevation of the first terrain map elevation points and the corresponding elevation extracted from the laser point cloud as a first difference value; in the case that the difference of the elevation points in the first terrain map is less than the first difference value, subtracting the difference mean value of the elevation points extracted from the first terrain map to obtain the elevation value of the new road terrain map elevation points; otherwise, taking the ground elevation of the ground laser points in the target range of the first terrain map elevation points as the new road terrain map elevation to obtain the elevation value of the new road terrain map elevation points. The application solves the problem that the terrain change cannot be found in time, can update the elevation points on the road in the terrain map, and improves the efficiency of the overall updating of the large-scale DLG.

Description

Technical Field

[0001] This invention belongs to the field of surveying and geographic information technology, and in particular relates to a method and system for updating DLG road elevation points based on vehicle-mounted point clouds. Background Technology

[0002] In the dynamic maintenance of large-scale topographic maps, the timeliness of the maps is ensured through a process of "detecting changes to updating changes." However, controlling the scale of the "detecting changes" stage is particularly challenging. Dynamic maintenance primarily involves "grid workers" inspecting the site with paper maps, marking changes on the paper, and then dispatching surveyors to update the maps. Changes can also be detected by comparing aerial or remote sensing imagery from two different periods, but changes in point features are difficult to detect. However, both manual inspections and image comparisons have the limitation of failing to detect changes in terrain undulations. The failure to promptly detect terrain changes in the "detecting changes" stage severely impacts the overall quality of the topographic map output. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method and system for updating DLG road elevation points based on vehicle-mounted point clouds.

[0004] In a first aspect, the present invention provides a method for updating DLG road elevation points based on vehicle-mounted point clouds, comprising:

[0005] Within the area where the elevation points of the road topographic map are located, the laser point cloud is superimposed with the corresponding elevation points of the road topographic map to obtain the first topographic map;

[0006] Determine the ground laser points within the target area of ​​the elevation points on the first topographic map;

[0007] The difference between the elevation of the first topographic map elevation point and the corresponding elevation extracted from the laser point cloud is determined and used as the first difference value.

[0008] In the case of elevation points whose difference is less than the first difference value in the first topographic map, the average difference value of the elevation points extracted from the first topographic map is subtracted to obtain the elevation value of the new road topographic map elevation points.

[0009] In the case of elevation points in the first topographic map with a difference not less than the first difference value, the ground elevation of the ground laser point within the target range of the elevation point in the first topographic map is taken as the new road topographic map elevation, and the elevation value of the new road topographic map elevation point is obtained.

[0010] Further, the ground laser points used to determine the target range of the first topographic map elevation point include:

[0011] The laser point cloud in the first topographic map is divided into multiple regions;

[0012] Obtain the extreme values ​​of the planar coordinates of the LAS file corresponding to each region;

[0013] Based on the maximum and minimum values ​​of the x-axis and y-axis among all the extreme values ​​of the planar coordinates, determine the number of rows and columns of the laser point cloud region;

[0014] Fill the corresponding areas with the topographic map elevation points;

[0015] Determine the elevation values ​​of ground laser points within the target area of ​​the road topographic map elevation point in all regions.

[0016] Further, determining the number of rows and columns of the laser point cloud region based on the maximum and minimum values ​​of the x-axis and y-axis among all planar coordinate extremes includes:

[0017] Calculate the number of rows H and columns V of the laser point cloud region using the following formulas:

[0018]

[0019] Where X_MAX is the maximum value of the x-axis among all extrema of the planar coordinate system; X_MIN is the minimum value of the x-axis among all extrema of the planar coordinate system; step is the side length of a single square region; Y_MAX is the maximum value of the y-axis among all extrema of the planar coordinate system; Y_MIN is the minimum value of the y-axis among all extrema of the planar coordinate system. This is the floor operator.

[0020] Furthermore, including:

[0021] Perform a columnar search of the elevation points on the road topographic map according to the target radius;

[0022] Determine if the search result is empty;

[0023] If the target radius is doubled, the search continues until the radius is greater than the radius threshold. If the search results are still empty when the radius is greater than the set radius threshold, the elevation value of the currently searched laser point is set to -999.0.

[0024] If not empty, then determine whether the thickness of the input point cloud is less than the thickness threshold;

[0025] If the thickness is less than the threshold, the current columnar search point cloud is determined to be a ground point, sorted according to elevation value, and the lowest point after removing the bottom 2% of points is taken as the required ground point.

[0026] If the thickness threshold is not less than the required thickness, the point cloud in the columnar section will be sorted by elevation value and the lowest point will be selected.

[0027] For the lowest point, use KD_Tree to search for the landing point of the trajectory line closest to the lowest point;

[0028] Determine whether the elevation difference between the lowest point and the landing point of the trajectory line closest to the lowest point is within the preset range;

[0029] If it is within the preset range, the lowest point will be taken as the required laser point;

[0030] If it is not within the preset range, mark the elevation value of the laser point corresponding to the lowest point as -999.0.

[0031] Secondly, the present invention provides a DLG road elevation point update system based on vehicle-mounted point clouds, comprising:

[0032] The overlay module is used to overlay the laser point cloud with the corresponding road topographic map elevation points within the range of the road topographic map elevation points to obtain the first topographic map;

[0033] The first determining module is used to determine the ground laser points within the target range of the first topographic map elevation point;

[0034] The second determining module is used to determine the difference between the elevation of the elevation point on the first topographic map and the corresponding elevation extracted from the laser point cloud, and use it as the first difference.

[0035] The mean subtraction module is used to subtract the mean difference of the elevation points extracted from the first topographic map when the difference between the elevation points in the first topographic map is less than the first difference, so as to obtain the elevation values ​​of the new road topographic map elevation points.

[0036] The third determining module is used to, when the difference between the elevation points on the first topographic map and the elevation points on the target range of the elevation points on the first topographic map is not less than the first difference value, take the ground elevation of the ground laser points within the target range of the elevation points on the first topographic map as the new elevation of the road topographic map, and obtain the elevation value of the new elevation points on the road topographic map.

[0037] Furthermore, the first determining module includes:

[0038] Regional division unit, used to divide the laser point cloud in the first topographic map into multiple regions;

[0039] The extreme value acquisition unit is used to obtain the plane coordinate extreme values ​​of the LAS file corresponding to each region.

[0040] The first determining unit is used to determine the number of rows and columns of the laser point cloud region based on the maximum and minimum values ​​of the x-axis and the y-axis among all the extreme values ​​of the planar coordinates.

[0041] Fill cells are used to fill the corresponding areas with topographic map elevation points;

[0042] The second determining unit is used to determine the elevation values ​​of ground laser points within the target range of road topographic map elevation points in all areas.

[0043] Further, the first determining unit includes:

[0044] A computing device is used to calculate the number of rows H and columns V of the laser point cloud region according to the following formula:

[0045]

[0046] Where X_MAX is the maximum value of the x-axis among all extrema of the planar coordinate system; X_MIN is the minimum value of the x-axis among all extrema of the planar coordinate system; step is the side length of a single square region; Y_MAX is the maximum value of the y-axis among all extrema of the planar coordinate system; Y_MIN is the minimum value of the y-axis among all extrema of the planar coordinate system. This is the floor operator.

[0047] Further, the second determining unit includes:

[0048] The first search device is used to perform a columnar search of the elevation points on the road topographic map according to the target radius;

[0049] The first judgment device is used to determine whether the search result is empty;

[0050] The first determining device is configured to, when the first judging device determines that the search result is empty, determine to expand the target radius by two times and continue searching until the radius is greater than the radius threshold; if the search result is still empty when the radius is greater than the set radius threshold, then set the elevation value of the currently searched laser point to -999.0.

[0051] The second judgment device is used to determine whether the thickness of the input point cloud is less than the thickness threshold when the first judgment device determines that the search result is not empty.

[0052] The second determining device is used to determine the current columnar search point cloud as ground points when the second determining device determines that the input point cloud thickness is less than the thickness threshold, sort the points according to the elevation value, remove the bottom 2% of the points, and take the lowest point as the required ground point.

[0053] The sorting device is used to sort the point cloud in the column according to the elevation value and take the lowest point when the second judgment device determines that the input point cloud thickness is not less than the thickness threshold.

[0054] The second search device is used to search for the landing point of the trajectory line closest to the lowest point using KD_Tree;

[0055] The third judgment device is used to determine whether the height difference between the lowest point and the landing point of the trajectory line closest to the lowest point is within a preset range;

[0056] The third determining device is used to determine the lowest point as the required laser point when the third judging device determines that it is within a preset range.

[0057] The fourth determining device is used to determine, when the third determining device determines that the elevation value of the laser point corresponding to the lowest point is not within the preset range, to mark it as -999.0.

[0058] Thirdly, the present invention provides a computer device, including a processor and a memory; wherein, when the processor executes a computer program stored in the memory, it implements the steps of the DLG road elevation point update method based on vehicle point cloud described in the first aspect.

[0059] Fourthly, the present invention provides a computer-readable storage medium for storing a computer program; when the computer program is executed by a processor, it implements the steps of the DLG road elevation point update method based on vehicle point cloud described in the first aspect.

[0060] This invention provides a method and system for updating DLG road elevation points based on vehicle-mounted point clouds. The method includes: overlaying laser point clouds with the corresponding road topographic map elevation points within the area where the road topographic map elevation points are located to obtain a first topographic map; determining ground laser points within the target area of ​​the first topographic map elevation points; determining the difference between the elevation of the first topographic map elevation points and the corresponding elevation extracted from the laser point cloud, as a first difference; for elevation points in the first topographic map where the difference is less than the first difference, subtracting the mean difference of the extracted elevation points from the first topographic map to obtain the new elevation value of the road topographic map elevation point; for elevation points in the first topographic map where the difference is not less than the first difference, using the ground elevation of the ground laser points within the target area of ​​the first topographic map elevation point as the new road topographic map elevation, thus obtaining the new elevation value of the road topographic map elevation point. This invention solves the problem that neither manual inspection nor image comparison can promptly detect terrain changes, and can automatically update road elevation points in the topographic map, improving the efficiency and quality of large-scale DLG overall updates. Attached Figure Description

[0061] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0062] Figure 1A flowchart illustrating a DLG road elevation point update method based on vehicle-mounted point cloud provided in an embodiment of the present invention;

[0063] Figure 2 This is an elevation rendering of a vehicle-mounted laser point cloud provided in an embodiment of the present invention;

[0064] Figure 3 This is an overlay effect diagram of vehicle-mounted laser point cloud and road topographic map elevation points provided in an embodiment of the present invention;

[0065] Figure 4 This is a ground laser point result map provided by an embodiment of the present invention, showing the results of searching for road elevation points.

[0066] Figure 5 This is a schematic diagram of a DLG road elevation point update system based on vehicle-mounted point cloud, provided in an embodiment of the present invention. Detailed Implementation

[0067] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0068] In one embodiment, such as Figure 1 As shown, this embodiment of the invention provides a method for updating road elevation points based on vehicle-mounted point clouds using DLG (Digital Line Graphic), including:

[0069] Step 101: Overlay the laser point cloud with the corresponding road topographic map elevation points within the area where the road topographic map elevation points are located to obtain the first topographic map.

[0070] In this step, point cloud data from the vehicle-mounted LiDAR, scan trajectory data, topographic map elevation point data, and topographic map road surface data of the target street are collected. The point cloud is a bidirectional scan, with the two point clouds containing 562,327,649 and 477,365,783 points respectively. Figure 2 The image shown is an elevation rendering of the vehicle-mounted point cloud. The absolute and relative accuracy of the point cloud data meet the requirements for a 1:500 topographic map, with a horizontal mean square error of less than or equal to 18 cm and an elevation mean square error of less than or equal to 11 cm. All collected data meet the required accuracy standards.

[0071] The ground elevation value at the same vertical position as the laser trajectory line is called the "trajectory landing elevation value", and this calculation process is called "trajectory line elevation landing". The trajectory line elevation landing is calculated as "trajectory landing elevation value = trajectory line elevation value - instrument installation height value". For example, the instrument height is set to 1.93m during data acquisition.

[0072] Because the collected point cloud has a high density, direct processing not only places high demands on computer hardware but also reduces the algorithm's execution efficiency. To avoid these issues, a thinning operation is required before use; here, a voxel grid downsampling method is adopted. Voxel grid downsampling divides the bounding box of the point cloud into cubes at a certain step size (0.2m). When a cube contains more than one point, its centroid is used to represent all points in the current cube.

[0073] The elevation points belonging to road surfaces in the topographic map are extracted and processed based on the road surface data. This part is done using the software ArcGIS.

[0074] Since the width of a road is generally within a specific range, for example, in order to remove the influence of non-road points as much as possible, laser points with a distance greater than 60m are filtered out based on the three-dimensional distance value.

[0075] During the scanning process, some low points may be generated due to mirror reflection and other reasons. The spatial distribution of these low points is significantly lower than the ground points. In order to remove the interference of these points as much as possible, the raw data is judged and points with elevation values ​​3m lower than the scanning trajectory line are filtered out.

[0076] After the above data preprocessing operations, the overlay effect of laser point cloud and road topographic map elevation points is as follows: Figure 3 As shown.

[0077] Step 102: Determine the ground laser points within the target range of the first topographic map elevation point.

[0078] This step includes:

[0079] The laser point cloud in the first topographic map is divided into multiple regions.

[0080] Obtain the extreme values ​​of the planar coordinates of the LAS file corresponding to each region.

[0081] The number of rows and columns of the laser point cloud region is determined based on the maximum and minimum values ​​of the x-axis and y-axis among all the extreme values ​​of the planar coordinates.

[0082] For example, the number of rows H and columns V of the laser point cloud region are calculated according to the following formula:

[0083]

[0084] Where X_MAX is the maximum value of the x-axis among all extrema of the planar coordinate system; X_MIN is the minimum value of the x-axis among all extrema of the planar coordinate system; step is the side length of a single square region; Y_MAX is the maximum value of the y-axis among all extrema of the planar coordinate system; Y_MIN is the minimum value of the y-axis among all extrema of the planar coordinate system. This is the floor operator.

[0085] The specified area is divided into rectangles with a certain side length (200m). The extreme values ​​of the plane coordinates (xmin, xmax, ymin, ymax) of each .las file in the target folder are read, and the minimum value of all xmin is taken as X_MIN, the maximum value of all xmax as X_MAX, the minimum value of all ymin as Y_MIN, and the maximum value of all ymax as Y_MAX. The calculated values ​​are X_MIN = 327204.564m, X_MAX = 327391.777m, Y_MIN = 346304.513m, and Y_MAX = 346479.215m, resulting in a value of 1 for H and 1 for V.

[0086] Fill the corresponding areas with the elevation points from the topographic map.

[0087] Determine the elevation values ​​of ground laser points within the target area of ​​the road topographic map elevation point in all regions.

[0088] For example, the elevation points of the road topographic map are searched in a columnar pattern according to the target radius.

[0089] Determine if the search results are empty.

[0090] If the target radius is doubled, the search continues until the radius is greater than the radius threshold. If the search results are still empty when the radius is greater than the set radius threshold, the elevation value of the currently searched laser point is set to -999.0.

[0091] If it is not empty, then determine whether the thickness of the input point cloud is less than the thickness threshold.

[0092] If the value is less than the thickness threshold, the current columnar search point cloud is determined as a ground point, sorted according to elevation value, and the lowest point after removing the bottom 2% of points is taken as the required ground point.

[0093] When the searched point cloud contains no ground points, or contains non-ground features such as ground, vegetation, and trees, the calculated point cloud thickness is greater than or equal to the thickness threshold. To better identify ground points, if the thickness is not less than the thickness threshold, the point cloud in the column is sorted by elevation value and the lowest point is selected.

[0094] Use KD_Tree to search for the landing point of the trajectory line closest to the lowest point.

[0095] Determine whether the height difference between the lowest point and the landing point of the trajectory line closest to the lowest point is within a preset range. In this embodiment, the preset range is a thickness threshold.

[0096] If it is within the preset range, the lowest point will be used as the required laser point.

[0097] If it is not within the preset range, mark the elevation value of the laser point corresponding to the lowest point as -999.0.

[0098] The program automatically calculates the difference between the elevation of a topographic map elevation point and the corresponding elevation extracted from the laser point cloud, and outputs a result file based on the user's input settings. Here, only a threshold interval of 0.15m is input. The result file contains three txt files: [0, 0.15), [0.15, +∞), and Empty (unit: m, file format: x, y, z). If the searched laser elevation value is -999.0, the search for the ground laser point is considered unsuccessful, and the laser point needs to be output to the "Empty.txt" file. The software prompt box outputs the total number of points, the number of points less than 15cm, the number of points greater than 15cm, and the number of points not found. Statistically, there are 57 input road topographic map elevation points, 45 points within the range [0, 0.15), 12 points within the range [0.15, +∞), and 0 points stored in the Empty.txt file.

[0099] Taking one point as an example, the obtained ground laser point is as follows: Figure 4 As shown.

[0100] Step 103: Determine the difference between the elevation of the first topographic map elevation point and the corresponding elevation extracted from the laser point cloud, and use it as the first difference.

[0101] Step 104: If the elevation difference in the first topographic map is less than the first difference value, the elevation difference mean of the elevation points extracted from the first topographic map is subtracted to obtain the elevation values ​​of the new road topographic map elevation points.

[0102] Step 105: If the elevation difference on the first topographic map is not less than the first difference value, the ground elevation of the ground laser point within the target range of the elevation point on the first topographic map is taken as the new road topographic map elevation, and the elevation value of the new road topographic map elevation point is obtained.

[0103] Steps 103-105, exemplarily, involve calculating the mean difference, offset, and variance for elevation points with a difference less than 15cm, and automatically generating a report. Then, the mean difference is subtracted from the elevation points extracted from each road topographic map to obtain new road topographic map elevation points. For elevation points with a difference greater than 15cm, the ground elevation of the laser point is directly used as the new road topographic map elevation value.

[0104] This invention provides a method for updating road elevation points based on vehicle-mounted point clouds using DLG (Digital Generation Gauge) technology. This method solves the problem that neither manual inspection nor image comparison can detect terrain changes in a timely manner. It can automatically update road elevation points on the topographic map, thereby improving the efficiency and quality of large-scale DLG updates.

[0105] Based on the same inventive concept, this invention also provides a DLG road elevation point update system based on vehicle-mounted point cloud. Since the principle of this system in solving the problem is similar to the aforementioned DLG road elevation point update method based on vehicle-mounted point cloud, the implementation of this system can refer to the implementation of the DLG road elevation point update method based on vehicle-mounted point cloud, and the repeated parts will not be described again.

[0106] In another embodiment, the UAV multi-stage signal source localization system based on cognitive learning provided in this invention, such as... Figure 5 As shown, it includes:

[0107] The overlay module 10 is used to overlay the laser point cloud with the corresponding road topographic map elevation points within the range of the road topographic map elevation points to obtain the first topographic map.

[0108] The first determining module 20 is used to determine the ground laser points within the target range of the first topographic map elevation point.

[0109] The second determining module 30 is used to determine the difference between the elevation of the elevation point on the first topographic map and the corresponding elevation extracted from the laser point cloud, as the first difference.

[0110] The mean subtraction module 40 is used to subtract the mean difference of the elevation points extracted from the first topographic map when the difference in elevation points on the first topographic map is less than the first difference value, so as to obtain the elevation value of the new road topographic map elevation point.

[0111] The third determining module 50 is used to, when the difference between the elevation points in the first topographic map and the elevation points in the target range of the elevation points in the first topographic map is not less than the first difference value, take the ground elevation of the ground laser points in the target range of the elevation points in the first topographic map as the new elevation of the road topographic map, and obtain the elevation value of the new elevation points in the road topographic map.

[0112] For example, the first determining module includes:

[0113] The region division unit is used to divide the laser point cloud in the first topographic map into multiple regions.

[0114] The extreme value acquisition unit is used to obtain the plane coordinate extreme values ​​of the LAS file corresponding to each region.

[0115] The first determining unit is used to determine the number of rows and columns of the laser point cloud region based on the maximum and minimum values ​​of the x-axis and the y-axis among all the extreme values ​​of the planar coordinates.

[0116] Fill cells are used to fill the corresponding areas with topographic map elevation points.

[0117] The second determining unit is used to determine the elevation values ​​of ground laser points within the target range of road topographic map elevation points in all areas.

[0118] For example, the first determining unit includes:

[0119] A computing device is used to calculate the number of rows H and columns V of the laser point cloud region according to the following formula:

[0120]

[0121] Where X_MAX is the maximum value of the x-axis among all extrema of the planar coordinate system; X_MIN is the minimum value of the x-axis among all extrema of the planar coordinate system; step is the side length of a single square region; Y_MAX is the maximum value of the y-axis among all extrema of the planar coordinate system; Y_MIN is the minimum value of the y-axis among all extrema of the planar coordinate system. This is the floor operator.

[0122] For example, the second determining unit includes:

[0123] The first search device is used to perform a columnar search of the elevation points on the road topographic map according to the target radius.

[0124] The first judgment device is used to determine whether the search result is empty.

[0125] The first determining device is configured to, if the first judging device determines that the search result is empty, determine to expand the target radius by two times and continue searching until the radius is greater than the radius threshold; if the search result is still empty when the radius is greater than the set radius threshold, then set the elevation value of the currently searched laser point to -999.0.

[0126] The second judgment device is used to determine whether the thickness of the input point cloud is less than a thickness threshold when the first judgment device determines that the search result is not empty.

[0127] The second determining device is used to determine the current columnar search point cloud as ground points when the second determining device determines that the input point cloud thickness is less than the thickness threshold, sort the points according to the elevation value, remove the bottom 2% of points and take the lowest point as the required ground point.

[0128] The sorting device is used to sort the point cloud in the column according to the elevation value and take the lowest point when the second judgment device determines that the thickness of the input point cloud is not less than the thickness threshold.

[0129] The second search device is used to search for the landing point of the trajectory line closest to the lowest point using KD_Tree.

[0130] The third judgment device is used to determine whether the height difference between the lowest point and the landing point of the trajectory line closest to the lowest point is within a preset range.

[0131] The third determining device is used to determine the lowest point as the required laser point when the third judging device determines that it is within a preset range.

[0132] The fourth determining device is used to determine, when the third determining device determines that the elevation value of the laser point corresponding to the lowest point is not within the preset range, to mark it as -999.0.

[0133] For more detailed information on the working process of each of the above modules, please refer to the relevant content disclosed in the foregoing embodiments, which will not be repeated here.

[0134] In another embodiment, the present invention provides a computer device including a processor and a memory; wherein, when the processor executes a computer program stored in the memory, it implements the steps of the above-described DLG road elevation point update method based on vehicle point cloud.

[0135] For more detailed information on the above methods, please refer to the relevant content disclosed in the foregoing embodiments, which will not be repeated here.

[0136] In another embodiment, the present invention provides a computer-readable storage medium for storing a computer program; when the computer program is executed by a processor, it implements the steps of the above-described DLG road elevation point update method based on vehicle point cloud.

[0137] For more detailed information on the above methods, please refer to the relevant content disclosed in the foregoing embodiments, which will not be repeated here.

[0138] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The systems, devices, and storage media disclosed in the embodiments are described simply because they correspond to the methods disclosed in the embodiments; relevant details can be found in the method section.

[0139] Those skilled in the art will clearly understand that the techniques in the embodiments of the present invention can be implemented using software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or certain parts of the embodiments of the present invention.

[0140] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for updating DLG road elevation points based on vehicle-mounted point clouds, characterized in that, include: Within the area where the elevation points of the road topographic map are located, the laser point cloud is superimposed with the corresponding elevation points of the road topographic map to obtain the first topographic map; Determine the ground laser points within the target area of ​​the elevation points on the first topographic map; The difference between the elevation of the first topographic map elevation point and the corresponding elevation extracted from the laser point cloud is determined and used as the first difference value. In the case of elevation points whose difference is less than the first difference value in the first topographic map, the average difference value of the elevation points extracted from the first topographic map is subtracted to obtain the elevation value of the new road topographic map elevation points. In the case of elevation points on the first topographic map with a difference not less than the first difference value, the ground elevation of the ground laser point within the target range of the elevation point on the first topographic map is used as the new road topographic map elevation, thus obtaining the elevation value of the new road topographic map elevation point.

2. The method for updating elevation points of DLG topographic maps based on vehicle-mounted point clouds according to claim 1, characterized in that, The ground laser points used to determine the target range of the first topographic map elevation point include: The laser point cloud in the first topographic map is divided into multiple regions; Obtain the extreme values ​​of the planar coordinates of the LAS file corresponding to each region; Based on the maximum and minimum values ​​of the x-axis and y-axis among all the extreme values ​​of the planar coordinates, determine the number of rows and columns of the laser point cloud region; Fill the corresponding areas with the topographic map elevation points; Determine the elevation values ​​of ground laser points within the target area of ​​the road topographic map elevation point in all regions.

3. The method for updating elevation points of DLG topographic maps based on vehicle-mounted point clouds according to claim 2, characterized in that, The step of determining the number of rows and columns of the laser point cloud region based on the maximum and minimum values ​​of the x-axis and y-axis among all the extreme values ​​of the planar coordinates includes: Calculate the number of rows H and columns V of the laser point cloud region using the following formulas: Where X_MAX is the maximum value of the x-axis among all extrema of the planar coordinate system; X_MIN is the minimum value of the x-axis among all extrema of the planar coordinate system; step is the side length of a single square region; Y_MAX is the maximum value of the y-axis among all extrema of the planar coordinate system; Y_MIN is the minimum value of the y-axis among all extrema of the planar coordinate system. This is the floor operator.

4. The method for updating elevation points of DLG topographic maps based on vehicle-mounted point clouds according to claim 2, characterized in that, The process of determining the elevation values ​​of ground laser points within the target range of road topographic map elevation points in all areas includes: Perform a columnar search of the elevation points on the road topographic map according to the target radius; Determine if the search result is empty; If the target radius is doubled, the search continues until the radius is greater than the radius threshold. If the search results are still empty when the radius is greater than the set radius threshold, the elevation value of the currently searched laser point is set to -999.

0. If not empty, then determine whether the thickness of the input point cloud is less than the thickness threshold; If the thickness is less than the threshold, the current columnar search point cloud is determined to be a ground point, sorted according to elevation value, and the lowest point after removing the bottom 2% of points is taken as the required ground point. If the thickness threshold is not less than the required thickness, the point cloud in the columnar section will be sorted by elevation value and the lowest point will be selected. For the lowest point, use KD_Tree to search for the landing point of the trajectory line closest to the lowest point; Determine whether the elevation difference between the lowest point and the landing point of the trajectory line closest to the lowest point is within the preset range; If it is within the preset range, the lowest point will be taken as the required laser point; If it is not within the preset range, mark the elevation value of the laser point corresponding to the lowest point as -999.

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5. A DLG road elevation point update system based on vehicle-mounted point cloud, characterized in that, include: The overlay module is used to overlay the laser point cloud with the corresponding road topographic map elevation points within the range of the road topographic map elevation points to obtain the first topographic map; The first determining module is used to determine the ground laser points within the target range of the first topographic map elevation point; The second determining module is used to determine the difference between the elevation of the elevation point on the first topographic map and the corresponding elevation extracted from the laser point cloud, and use it as the first difference. The mean subtraction module is used to subtract the mean difference of the elevation points extracted from the first topographic map when the difference between the elevation points in the first topographic map is less than the first difference, so as to obtain the elevation values ​​of the new road topographic map elevation points. The third determining module is used to, when the difference between the elevation points on the first topographic map and the elevation points on the target range of the elevation points on the first topographic map is not less than the first difference value, take the ground elevation of the ground laser points within the target range of the elevation points on the first topographic map as the new elevation of the road topographic map, and obtain the elevation value of the new elevation points on the road topographic map.

6. The DLG topographic map elevation point update system based on vehicle-mounted point cloud as described in claim 5, characterized in that, The first determining module includes: Regional division unit, used to divide the laser point cloud in the first topographic map into multiple regions; The extreme value acquisition unit is used to obtain the plane coordinate extreme values ​​of the LAS file corresponding to each region. The first determining unit is used to determine the number of rows and columns of the laser point cloud region based on the maximum and minimum values ​​of the x-axis and the y-axis among all the extreme values ​​of the planar coordinates. Fill cells are used to fill the corresponding areas with topographic map elevation points; The second determining unit is used to determine the elevation values ​​of ground laser points within the target range of road topographic map elevation points in all areas.

7. The DLG topographic map elevation point update system based on vehicle-mounted point cloud as described in claim 6, characterized in that, The first determining unit includes: A computing device is used to calculate the number of rows H and columns V of the laser point cloud region according to the following formula: Where X_MAX is the maximum value of the x-axis among all extrema of the planar coordinate system; X_MIN is the minimum value of the x-axis among all extrema of the planar coordinate system; step is the side length of a single square region; Y_MAX is the maximum value of the y-axis among all extrema of the planar coordinate system; Y_MIN is the minimum value of the y-axis among all extrema of the planar coordinate system. This is the floor operator.

8. The DLG topographic map elevation point update system based on vehicle-mounted point cloud as described in claim 6, characterized in that, The second determining unit includes: The first search device is used to perform a columnar search of the elevation points on the road topographic map according to the target radius; The first judgment device is used to determine whether the search result is empty; The first determining device is configured to, when the first judging device determines that the search result is empty, determine to expand the target radius by two times and continue searching until the radius is greater than the radius threshold; if the search result is still empty when the radius is greater than the set radius threshold, then set the elevation value of the currently searched laser point to -999.

0. The second judgment device is used to determine whether the thickness of the input point cloud is less than the thickness threshold when the first judgment device determines that the search result is not empty. The second determining device is used to determine the current columnar search point cloud as ground points when the second determining device determines that the input point cloud thickness is less than the thickness threshold, sort the points according to the elevation value, remove the bottom 2% of the points, and take the lowest point as the required ground point. The sorting device is used to sort the point cloud in the column according to the elevation value and take the lowest point when the second judgment device determines that the input point cloud thickness is not less than the thickness threshold. The second search device is used to search for the landing point of the trajectory line closest to the lowest point using KD_Tree; The third judgment device is used to determine whether the height difference between the lowest point and the landing point of the trajectory line closest to the lowest point is within a preset range; The third determining device is used to determine the lowest point as the required laser point when the third judging device determines that it is within a preset range. The fourth determining device is used to determine, when the third determining device determines that the elevation value of the laser point corresponding to the lowest point is not within the preset range, to mark it as -999.

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9. A computer device, characterized in that, It includes a processor and a memory; wherein, when the processor executes the computer program stored in the memory, it implements the steps of the DLG road elevation point update method based on vehicle point cloud as described in any one of claims 1-4.

10. A computer-readable storage medium, characterized in that, Used to store computer programs; when executed by a processor, the computer programs implement the steps of the DLG road elevation point update method based on vehicle point cloud as described in any one of claims 1-4.

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