A lidar detection point setting device and a method for extracting the coordinates of its detection points

Abstract

The present invention relates to the field of lidar scanning measurement, in particular to a lidar detection point setting device and a method for extracting the coordinates of its detection points. A lidar detection point setting device includes a cylinder, an open container, and a leveling device. The cylinder is vertically centered inside the open container, and the top surface of the cylinder is above the top surface of the open container. The leveling device is used to level the open container. The cross-sectional shape of the open container is a regular polygon or a circle, and there is a liquid storage area for storing water between the cylinder and the open container. With the lidar ground detection point setting device of the present invention, the side surface of the cylinder will not be affected during lidar scanning. By storing water in the liquid storage area, the search range for extracting coordinates during lidar scanning can be reduced, and the detection points are easier to locate when extracting point cloud coordinates, minimizing the errors caused by mispositioning as much as possible.

Description

Technical Field

[0001] The present invention relates to the field of lidar scanning measurement, and in particular to a lidar detection point setting device and a method for extracting the coordinates of the detection point thereof. Background Art

[0002] With the progress and development of technology, ground scanning using lidar has been increasingly widely applied.

[0003] When using lidar to scan the ground, point clouds will be obtained, and the point clouds need to be processed. However, before further processing the point clouds, it is necessary to detect the accuracy of the point clouds to ensure the subsequent quality. The commonly used method is to find feature points on the ground, such as the corners of buildings, etc., as the detection points. After selecting the detection points, the actual three-dimensional coordinates of the detection points are measured by using a total station or a real-time kinematic carrier phase differential technology method. Then, the point clouds are checked to find the three-dimensional coordinates of the point closest to the detection point, and compared with the actual three-dimensional coordinates of the detection point. The larger the difference, the worse the accuracy; the smaller the difference, the higher the accuracy.

[0004] However, this method for detecting accuracy has great limitations: when extracting the coordinates of the detection points from the point clouds, only based on the differences in the point cloud density, distribution, and height, the positions of the detection points are identified by the naked eye. It is not easy to locate the detection points during extraction, and large errors are likely to occur. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problem in the prior art that it is not easy to locate the detection points when extracting the detection points from the point clouds, which easily causes large errors in the extraction of the detection point coordinates, and provides a lidar detection point setting device and a method for extracting the coordinates of the detection point thereof.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] A lidar detection point setting device includes a cylinder, an open container, and a leveling device. The cylinder is vertically and centrally arranged inside the open container, the top surface of the cylinder is above the top surface of the open container, the leveling device is used to level the open container, the cross-sectional shape of the open container is a regular polygon or a circle, and there is a liquid storage area for storing water between the cylinder and the open container.

[0008] When the lidar scans, the detection points are positioned on the top surface of the cylinder. There is a liquid storage area between the cylinder and the open container for holding water. Since there is no echo or very few echoes on the water surface during lidar scanning, there is a relatively dense point cloud on the top of the cylinder, while there is no point cloud in the liquid storage area. Compared with the prior art, the search range for extracting coordinates is reduced, and it is easier to locate the cylinder when extracting the point cloud coordinates. The leveling device is used to level the open container to ensure the leveling of the entire lidar ground detection point setting device, which can reduce the errors caused by the lidar ground detection point setting device not being in a horizontal state during scanning. To ensure that the side of the cylinder is not affected during laser scanning, the top surface of the cylinder is above the top surface of the open container. The cross-section of the open container is a regular polygon or a circle, and it is easier to position the cylinder at the center of the open container during installation and easier to level. The materials and dimensions of this lidar ground detection point setting device depend on specific circumstances.

[0009] When using this lidar ground detection point setting device, water is stored in the liquid storage area. Since there is no echo or very few echoes on the water surface during lidar scanning, there is a relatively dense point cloud on the top of the cylinder, and at the same time, there is no point cloud in the liquid storage area. This can make the lidar reduce the search range for extracting coordinates compared with the prior art during scanning. When extracting the point cloud coordinates, the detection points are narrowed down to the top surface of the cylinder, making the detection points easier to locate and minimizing the error in accuracy judgment caused by mispositioning as much as possible.

[0010] Preferably, the cross-sectional shape of the open container is a circle.

[0011] Setting the cross-sectional shape of the open container as a circle ensures that the distance between the open container and the cylinder is equal everywhere. At the same time, the circle also ensures that it is more convenient to set the leveling device and easier to level.

[0012] Preferably, the leveling device includes leveling bolts.

[0013] The number and distribution of the leveling bolts depend on specific circumstances. The leveling bolts can make the adjustment more subtle when leveling this lidar ground detection point setting device, and because the threads on the bolts are also stable after leveling, the leveling is simplified.

[0014] Preferably, a spirit level is provided on the top surface of the cylinder, and the top surface of the spirit level is flush with the top surface of the cylinder.

[0015] There is a spirit bubble inside the spirit level, which can intuitively judge whether the entire lidar ground detection point setting device is in a balanced state. The balanced state is convenient for the lidar to scan the top surface of the cylinder intuitively and accurately, reducing errors.

[0016] Preferably, there is a crosshair-shaped positioning point at the center of the top of the cylinder.

[0017] During lidar scanning, the detection point is positioned at the positioning point. The detection point adopts the form of a crosshair, which is more obvious when marking the detection point. Therefore, it is easier to extract the point cloud coordinates of the detection point. In addition, when the device is used to obtain the measured coordinates of the detection point, the crosshair also makes the positioning more definite during the actual measurement of the detection point.

[0018] A method for extracting the coordinates of a detection point, using the above-mentioned lidar detection point setting device, includes the following steps:

[0019] S1. Define the area: Define a preset area around the open container, and the preset area completely covers the open container;

[0020] S2. Divide the cells: Divide the preset area into several cells, and the cells are in the shape of regular polygons. The side length d of the cell is:

[0021]

[0022] In the formula, L B represents the minimum value of the perpendicular from the center of the cylinder to the side length of the open container or the radius of the open container, R A represents the radius of the cylinder, and n is a constant. The value of n is determined according to the shape of the cell. The selection of the constant n can divide the liquid storage area into 1 or 2 cells;

[0023] S3. Determine the preliminary point cloud coordinates of the detection point

[0024] Set up a Cartesian rectangular coordinate system in the area with the vertical direction as the Z-axis. Take the cell with the number of internal point clouds equal to 0 as the first cell and extract the central plane coordinates of the first cell. Take the average value of the maximum and minimum values of the coordinate values in the X-axis direction of the first cell as Then take the average value of the maximum and minimum values of the coordinate values in the Y-axis direction of the first cell as Thus, determine the preliminary point cloud coordinates of the detection point

[0025] S4. Determine the coordinate set (X k , Y k , Z k ) located on the cylinder:

[0026] Calculate the horizontal distance R from each point inside the area to the preliminary point cloud coordinates j of the detection point. Determine the coordinate set (X j , Y k , Z k , Z k ) located on the cylinder from R

[0027] S5. Determine the point cloud coordinates (X0, Y0, Z0) of the detection point:

[0028] First, extract the set of coordinate points (X H , Y H , Z H ) on the side surface of the cylinder. Then, according to the analytical formula of the circle and the least square principle, calculate the planar point cloud coordinates (X0, Y0) of the detection point. After that, based on the distance from the points on the cylinder to the planar point cloud coordinates (X0, Y0) of the detection point, obtain the set of coordinates (X V , Y V , Z V ) of the top surface of the cylinder. Finally, based on the set of coordinates of the top surface of the cylinder, calculate the Z-axis coordinate Z0 of the detection point, and finally determine the point cloud coordinates (X0, Y0, Z0) of the detection point.

[0029] When the lidar scans, set the center of the top surface of the cylinder as the detection point. After determining the point cloud coordinates (X0, Y0, Z0) of the detection point, compare them with the measured coordinates of the detection point to judge the scanning accuracy of the lidar.

[0030] Ensure that the open container is located inside the demarcated area, that is, ensure that the entire lidar ground detection point setting device is located inside the demarcated area.

[0031] Determine that the constant n in the cell size calculation formula depends on the size of the lidar ground detection point setting device. When the cells cannot cover the entire preset area, the remaining edge part is directly discarded.

[0032] The coordinate axes used in this center coordinate extraction method are the Cartesian rectangular coordinate system. Determine the vertical direction as the Z-axis, and the directions of the X-axis and Y-axis are determined according to the specific situation.

[0033] Adopting this detection point coordinate extraction method saves more time compared to directly extracting the detection point coordinates from the point cloud. In addition, due to the resolution of the point cloud, there is no guarantee that there is a point cloud at the detection point during lidar scanning, so only the coordinates of the nearest point cloud can be extracted. By adopting this detection point coordinate extraction method, the error caused by the point cloud resolution is effectively reduced, the coordinate extraction of the detection point is more accurate, and the impact on the accuracy evaluation of the lidar is also smaller.

[0034] Preferably, in step S1, demarcate a preset area with the measured coordinates (X1, Y1, Z1) of the detection point as the center.

[0035] The measured coordinates (X1, Y1, Z1) of the detection point are measured by using a total station or a real-time kinematic carrier phase differential technology method. With the measured coordinates (X1, Y1, Z1) of the detection point as the center, it is possible to ensure that the lidar ground detection point setting device is as close as possible to the center of the delimited area range and is as much as possible within the delimited area range, so as to ensure the accuracy during the extraction of the point cloud coordinates.

[0036] Preferably, the cell is a square grid, and the side length of the square grid is:

[0037]

[0038] In the formula, L B represents the minimum value of the perpendicular line from the center of the circle of the cylinder to the side length of the open container or the radius of the open container, and R A represents the radius of the cylinder.

[0039] The constant n is selected as 3, so that the number of square grids in the liquid storage area between the cylinder and the open container is 1 or 2, ensuring that the preliminary point cloud coordinates of the detection point will not deviate too much, so as to ensure that the error of the finally calculated point cloud coordinates (X0, Y0, Z0) of the detection point is not too large and reduce the error of accuracy judgment.

[0040] Using square grids can not only ensure that the entire lidar ground detection point setting device is covered, but also relatively easily determine the coordinates of the center point. It speeds up the extraction speed of the center point coordinates while ensuring the accuracy of the extraction of the center point coordinates and reduces the error of accuracy judgment.

[0041] Preferably, when determining the coordinate set (X k , Y k , Z k ) on the cylinder, the horizontal distance R from each point inside the area to the preliminary point cloud coordinates j needs to satisfy the following formula:

[0042] R j < R A + d

[0043] In the formula, R A represents the radius of the cylinder, and d represents the side length of the cell.

[0044] By making R A + d, the range located on the cylinder is appropriately expanded, and it is ensured that each square grid located on the cylinder is included as much as possible, ensuring that the side coordinates of the cylinder are all extracted. Then, during the calculation process of the analytical formula of the circle later, it can be ensured that the calculation results of X0 and Y0 are as accurate as possible, and the point cloud coordinates (X0, Y0, Z0) are as accurate as possible.

[0045] Preferably, step S5 includes the following steps:

[0046] S51. Extract the set of coordinate points (X H , Y H , Z H ) on the side surface of the cylinder: Extract the set of coordinate points (X k , Y k , Z k ) on the side surface of the cylinder from the coordinate set (X H , Y H , Z H ) on the cylinder. The judgment criterion is as follows:

[0047] Z H < Z max -m

[0048] In the formula, Z H is the Z coordinate value on the cylinder, Z max is the maximum value of the Z coordinate values on the cylinder, and m is the error rejection number. The error rejection number m is determined according to the size of the lidar detection point setting device. Through this, the set of coordinate points (X H , Y H , Z H ) on the side surface of the cylinder is extracted;

[0049] S52. Determine the planar point cloud coordinates (X0, Y0) of the detection point:

[0050] The analytical formula of the circle on the top surface of the cylinder is:

[0051]

[0052] Calculate X0 and Y0 by the least squares method to determine the planar point cloud coordinates (X0, Y0) of the detection point;

[0053] S53. Determine the set of coordinate points (X V , Y V , Z V ) on the top surface of the cylinder: Calculate the horizontal distance R k from the set of points on the cylinder to (X0, Y0):

[0054]

[0055] In the formula, X k is the X coordinate value on the cylinder, and Y k is the Y coordinate value on the cylinder;

[0056] The judgment formula for the coordinate points located on the top surface of the cylinder is as follows:

[0057] RK <R A -m

[0058] The set of coordinate points (X V , Y V , Z V ) of the top surface of the cylinder is determined by this formula;

[0059] S54. Determine the point cloud coordinates (X0, Y0, Z0) of the detection point: Z0 is obtained by the following formula:

[0060]

[0061] In the formula, p is the number of points on the top surface of the cylinder, and Z V is the Z coordinate of the coordinate point on the top surface of the cylinder. Finally, the point cloud coordinates (X0, Y0, Z0) of the detection point can be determined by this formula.

[0062] The value of the error rejection number m is determined according to the size of the ground detection point setting device of the lidar. By setting the error rejection number m in this center coordinate extraction method, it can be ensured as much as possible that (X H , Y H , Z H ) is on the side surface of the cylinder and (X V , Y V , Z V ) is on the top surface of the cylinder. The value of Z0 is determined by the average value of the Z values of all coordinates on the top surface of the cylinder, which can reduce the error of Z0 as much as possible and ensure the accuracy of the point cloud coordinates of the detection point.

[0063] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0064] 1. By using the above-mentioned lidar detection point setting device, the side surface of the cylinder will not be affected during lidar scanning. When water is filled in the liquid storage area, the lidar can reduce the search range for extracting coordinates compared with the prior art during scanning. When extracting point cloud coordinates, the detection point is easier to locate, and the error of accuracy judgment caused by mispositioning is reduced as much as possible;

[0065] 2. By using the above-mentioned coordinate extraction method for the detection point, it saves more time compared with directly extracting the detection point coordinates from the point cloud. In addition, due to the resolution of the point cloud, there is no guarantee that there is a point cloud on the detection point during lidar scanning, and only the coordinates of the nearest point cloud can be extracted. By using this center coordinate extraction method, the error caused by the point cloud resolution is effectively reduced, the coordinate extraction of the detection point is more accurate, and the impact on the accuracy evaluation of the lidar is also smaller. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1Schematic structural diagram of a lidar detection point setting device in Embodiment 1;

[0067] Figure 2 Top view of the structure of a lidar detection point setting device in Embodiment 1;

[0068] Figure 3 Schematic diagram of the defined range in Embodiment 2;

[0069] Figure 4 Flowchart of a method for extracting the coordinates of a detection point in Embodiment 2.

[0070] Markings in the figure: 1 - level, 2 - positioning point, 3 - leveling device, 4 - cylinder, 5 - open container, 6 - liquid storage area. Detailed implementation manners

[0071] The present invention will be further described in detail below in conjunction with test examples and specific implementation manners. However, it should not be understood that the scope of the above - mentioned subject matter of the present invention is limited to the following embodiments. All technologies implemented based on the content of the present invention belong to the scope of the present invention.

[0072] Embodiment 1

[0073] As Figure 1-2 shown, a lidar detection point setting device includes a cylinder 4, an open container 5, and a leveling device 3. The cylinder 4 is vertically centered inside the open container 5, and the top surface of the cylinder 4 is above the top surface of the open container 5. The leveling device 3 is used to level the open container 5. The cross - sectional shape of the open container 5 is a regular polygon or a circle. There is a liquid storage area 6 for holding water between the cylinder 4 and the open container 5. The sizes and materials of the cylinder 4 and the open container 5 are determined according to specific circumstances. In this embodiment, the cross - sectional shape of the open container 5 is a circle. The radius difference between the open container 5 and the cylinder 4 is determined according to the actual situation.

[0074] The leveling device 3 includes leveling bolts. The number and arrangement of the leveling bolts are determined according to specific circumstances. In this embodiment, three leveling bolts are evenly distributed under the side surface of the open container 5, as Figure 2 shown.

[0075] A level 1 is provided on the top surface of the cylinder 4, and the top surface of the level 1 is flush with the top surface of the cylinder 4. There is a positioning point 2 in the form of a crosshair at the center of the top of the cylinder 4.

[0076] Embodiment 2

[0077] As Figure 4 shown, a method for extracting the coordinates of a detection point, using a lidar detection point setting device in Embodiment 1, includes the following steps:

[0078] S1. Designated area: Designate a preset area around the open container 5, and the preset area completely covers the open container 5;

[0079] S2. Divide into cells: Divide the preset area into several cells, and the cells are in the shape of regular polygons. The side length d of the cells is:

[0080]

[0081] In the formula, L B represents the minimum value of the perpendicular line from the center of the cylinder 4 to the side length of the open container 5 or the radius of the open container 5, R A represents the radius of the cylinder 4, and n is a constant. The value of n is determined according to the shape of the cell. The selection of the constant n can divide the liquid storage area into 1 or 2 cells;

[0082] S3. Determine the initial point cloud coordinates of the detection point

[0083] Set up a Cartesian rectangular coordinate system in the area with the vertical direction as the Z-axis. Take the cell with the internal point cloud number of 0 as the first cell and extract the central plane coordinates of the first cell. Take the average value of the maximum and minimum values of the X-axis direction coordinate values of the first cell as Then take the average value of the maximum and minimum values of the Y-axis direction coordinate values of the first cell as Thus, determine the initial point cloud coordinates of the detection point

[0084] S4. Determine the coordinate set (X k , Y k , Z k ) located on the cylinder 4:

[0085] Calculate the horizontal distance R from each point inside the area to the initial point cloud coordinates of the detection point , and determine the coordinate set (X j from R j , Y k , Z k , Z k ) located on the cylinder 4;

[0086] S5. Determine the point cloud coordinates (X0, Y0, Z0) of the detection point:

[0087] First, extract the coordinate point set (X H , Y H , Z H), and then, according to the analytic formula of the circle and the least square principle, the planar point cloud coordinates (X0, Y0) of the detection point are obtained. After that, according to the distances from the points on the cylinder 4 to the planar point cloud coordinates (X0, Y0) of the detection point, the coordinate set (X V , Y V , Z V ) of the top surface of the cylinder 4 is obtained. Finally, according to the coordinate set of the top surface of the cylinder 4, the Z-axis coordinate Z0 of the detection point is obtained, and finally the point cloud coordinates (X0, Y0, Z0) of the detection point are determined.

[0088] In step S1, a preset area is delimited with the measured coordinates (X1, Y1, Z1) of the detection point as the center. In this embodiment, a square with a side length of 5 m is selected, the value range of X is X1 - 2.5 to X1 + 2.5, and the value range of Y is Y1 - 2.5 to Y1 + 2.5, as Figure 3 shown.

[0089] The cells are squares, and the side length of the square is:

[0090]

[0091] In the formula, L B represents the minimum value of the perpendicular line from the center of the cylinder 4 to the side length of the open container 5 or the radius of the open container 5, and R A represents the radius of the cylinder 4.

[0092] When determining the coordinate set (X k , Y k , Z k ) on the cylinder 4, the horizontal distance R from each point inside the preset area to the preliminary point cloud coordinates j of the detection point needs to satisfy the following formula:

[0093] R j < R A + d

[0094] In the formula, R A represents the radius of the cylinder 4, and d represents the side length of the cell.

[0095] Step S5 includes the following steps:

[0096] S51. Extract the coordinate point set (X H , Y H , Z H ) of the side surface of the cylinder 4: Extract the coordinate point set (X k , Y k , Z k ) of the side surface of the cylinder 4 from the coordinate set (X H , Y H , ZH ), the judgment criteria are as follows:

[0097] Z H <Z max -m

[0098] where Z H is the Z coordinate value on the cylinder 4, and Z max is the maximum value of the Z coordinate value on the cylinder 4, and m is the error rejection number. The error rejection number m is determined according to the size of the lidar detection point setting device. Through this, the set of coordinate points (X H , Y H , Z H ) on the side of the cylinder 4 is extracted;

[0099] S52. Determine the plane point cloud coordinates (X0, Y0) of the detection point:

[0100] The analytical formula of the circle on the top surface of the cylinder 4 is:

[0101]

[0102] Calculate X0 and Y0 by the least squares method to determine the plane point cloud coordinates (X0, Y0) of the detection point;

[0103] S53. Determine the set of coordinate points (X V , Y V , Z V ) on the top surface of the cylinder 4:

[0104] Calculate the horizontal distance R from the set of points on the cylinder 4 to (X0, Y0) k :

[0105]

[0106] where X k is the X coordinate value on the cylinder 4, and Y k is the Y coordinate value on the cylinder 4;

[0107] The judgment formula for the coordinate points located on the top surface of the cylinder 4 is as follows:

[0108] R K <R A -m

[0109] Determine the set of coordinate points (X V , Y V , Z V ) on the top surface of the cylinder 4 through this formula;

[0110] S54. Determine the point cloud coordinates (X0, Y0, Z0) of the detection point: Z0 is obtained by the following formula:

[0111]

[0112] Where p is the number of points on the top surface of the cylinder 4, and Z V is the Z coordinate of the coordinate point on the top surface of the cylinder 4. Through this formula, the point cloud coordinates (X0, Y0, Z0) of the detection point can be finally determined.

[0113] m is the number of error rejection numbers, which is determined according to the size of the lidar detection point setting device. In this embodiment, m = 0.05, and the unit is meter.

[0114] When the lidar performs scanning, the center of the top surface of the cylinder 4 is set as the detection point. After determining the point cloud coordinates (X0, Y0, Z0) of the detection point, compare them with the measured coordinates (X1, Y1, Z1) of the detection point to detect the scanning accuracy of the lidar.

[0115] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A lidar detection point setting device, characterized in that It includes a cylinder (4), an open container (5) and a leveling device (3). The cylinder (4) is vertically centered inside the open container (5), the top surface of the cylinder (4) is above the top surface of the open container (5), the leveling device (3) is used to level the open container (5), the cross-sectional shape of the open container (5) is a regular polygon or a circle, and there is a liquid storage area (6) for holding water between the cylinder (4) and the open container (5); There is a positioning point (2) in the shape of a crosshair at the center of the top surface of the cylinder (4). When the lidar scans, the detection point is positioned at the positioning point.

2. The laser radar detection point setting device according to claim 1, characterized in that The cross-sectional shape of the open container (5) is a circle.

3. The laser radar detection point setting device according to claim 1, wherein, The leveling device (3) includes leveling bolts.

4. The laser radar detection point setting device according to claim 1, characterized in that, A level (1) is provided on the top surface of the cylinder (4), and the top surface of the level (1) is flush with the top surface of the cylinder (4).

5. A method for extracting the coordinates of detection points, which uses a lidar detection point setting device as described in any one of claims 1-4, characterized in that, It includes the following steps: S1. Designated area: Designate a preset area around the open container (5), and the preset area completely covers the open container (5). Designate the preset area with the measured coordinates of the detection point as the center; S2. Divide cells: Divide the preset area into a number of cells, where the cells are regular polygon shapes, and the side length of the cells is as follows: wherein represents the minimum value of the perpendicular distance from the center of the cylinder (4) to the side length of the open container (5) or the radius of the open container (5), represents the radius of the cylinder (4), is a constant determined according to the shape of the cell for the value of, the constant is selected such that at least one cell can be radially divided in the liquid storage area; S3. Determine the preliminary point cloud coordinates of the detection points :[[-]] Set up a Cartesian rectangular coordinate system in the preset area with the vertical direction as axis, and take several cells with the number of internal point clouds being 0 as the first cells. The first cells are located in the liquid storage area (6), and extract the central plane coordinates of the first cells. Take the average value of the maximum and minimum values of the coordinate values in the axis direction of the first cells as , and then take the average value of the maximum and minimum values of the coordinate values in the axis direction of the first cells as , thereby determining the preliminary point cloud coordinates of the detection point ; S4. Determine the set of coordinates located on the cylinder (4) :[[-END]] Calculate the preliminary point cloud coordinates of each point inside the preset area to the detection point Horizontal distance , determined by Determine the coordinate set located on the cylinder (4) ; S5. Determine the point cloud coordinates of the detection point : First, extract the set of coordinate points on the side surface of the cylinder (4). , and then calculate the planar point cloud coordinates of the detection point according to the analytical formula of the circle and the least square principle. , and then, according to the distance between the points on the cylinder (4) and the planar point cloud coordinates of the detection point , obtain the set of coordinates of the top surface of the cylinder (4). , and finally, according to the set of coordinates of the top surface of the cylinder (4), calculate the axial coordinate , and finally determine the point cloud coordinates of the detection point .

6. The coordinate extraction method of a detection point according to claim 5, wherein, The cell is a square grid, and the side length of the square grid is: wherein represents the minimum value of the perpendicular distance from the center of the cylinder (4) to the side length of the open container (5) or the radius of the open container (5), represents the radius of the cylinder (4).

7. The coordinate extraction method of a detection point according to claim 6, characterized in that, Determine the set of coordinates located on the cylinder (4) When the initial point cloud coordinates of each point inside the preset area to the detection point Horizontal distance Must satisfy the following formula: wherein represents the radius of the cylinder (4), represents the side length of the unit cell.

8. The coordinate extraction method of a detection point according to claim 5, wherein Step S5 includes the following steps: S51. Extract the set of coordinate points on the side surface of the cylinder (4). : From the coordinate set on the cylinder (4) Extract the set of coordinate points on the side surface of the cylinder (4). , and the judgment criteria are as follows: In the formula is the coordinate value on the said cylinder (4), is the maximum value of the coordinate value on the said cylinder (4), is the error rejection number, and the error rejection number is determined according to the size of the said lidar detection point setting device, and the coordinate point set on the side surface of the said cylinder (4) is extracted through this ; S52. Determine the planar point cloud coordinates of the detection point : The analytical formula of the circle on the top surface of the cylinder (4) is: Calculated by the least squares method , , and determine the planar point cloud coordinates of the detection point ; S53. Determine the set of coordinate points of the top surface of the cylinder (4) :[[-END]] Calculate the horizontal distance from the set of points on the cylinder (4) to the horizontal distance : wherein is the coordinate value on the said cylinder (4), is the coordinate value on the said cylinder (4); The coordinate point judgment formula located on the top surface of the cylinder (4) is as follows: Determine the set of coordinate points of the top surface of the cylinder (4) through this formula ; S54. Determine the point cloud coordinates of the detection point : Obtained by the following formula: wherein is the number of points on the top surface of the cylinder (4), is the coordinate of the coordinate point on the top surface of the cylinder (4), and finally the point cloud coordinate of the detection point can be determined by this formula .

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