Automatic detection method for verticality of large batch bridge piers based on ground 3D scanning

Abstract

The present invention relates to the technical field of bridge pier verticality measurement, and discloses a method for automated detection of large-scale bridge pier verticality based on ground three-dimensional scanning, comprising the following steps: S1: arranging a three-dimensional laser scanner and a target sphere, and registering a single-site cloud collected by the three-dimensional laser scanner based on the target sphere to obtain a bridge and environment point cloud; S2: extracting the bridge point cloud; S3: segmenting the point cloud to obtain a local coordinate system; S4: extracting the bridge pier point cloud; S5: determining the cross-sectional shape of the bridge pier; and S6: detecting the verticality of the bridge pier. Thus, the method can fit a continuous, high-precision bridge pier axis by collecting a large amount of point cloud data, and uses the centroid coordinates of all fitted bridge pier point cloud slices to calculate the verticality of different bridge pier cross-sectional contours based on the angle between the axis equation and the vertical direction, thereby increasing the accuracy of the measured data. In addition, the present application realizes the automatic segmentation of bridge pier point clouds in large-scale bridges and the batch detection of bridge piers.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge pier verticality measurement, and in particular to a method for automatically detecting the verticality of large quantities of bridge piers based on three-dimensional ground scanning. Background Art

[0002] Currently, small and medium-span bridges account for a high proportion and are the primary component of high-speed bridges. Piers, as the supporting structure of the main beam, have a direct impact on bridge safety due to their condition. As a key indicator of pier health, rapid and accurate measurement of pier verticality during construction and operation is crucial.

[0003] The most commonly used methods for checking bridge pier verticality include total stations and bridge inspection vehicles. Traditional methods like total stations are inefficient and labor-intensive. They only allow for single-point measurements, requiring multiple measurements for a single pier, resulting in a significant workload for verticality testing. Furthermore, total station-based methods require measurements in two perpendicular directions, which is difficult to achieve in rugged mountainous terrain and poses challenges in verifying the verticality of piers with varying cross-sections. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a method for automated detection of the verticality of large quantities of bridge piers based on ground three-dimensional scanning. The method adopts ground laser scanning (TLS) and has the characteristics of fast speed, high precision and high reliability. For the detection of the verticality of bridge piers, it can perform batch verticality detection on bridge piers with different cross-sections and environments.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] A method for automatically detecting the verticality of large quantities of bridge piers based on ground 3D scanning comprises the following steps: S1, collecting a single-site cloud based on a 3D laser scanner and a target ball, identifying the target ball point cloud in the single-site cloud, and obtaining an overall point cloud model of the bridge and its surrounding environment by target ball point cloud registration; S2, segmenting the overall point cloud model to obtain a bridge point cloud; S3, estimating the bridge route of the bridge, slicing the bridge point cloud along the bridge route to obtain a number of first slices, obtaining peak slices among the first slices, extracting a pier area point cloud from the bridge point cloud based on the peak slices, and establishing a local coordinate system for the pier area point cloud; S4, in the local coordinates Slice along the second direction to obtain several second slices, count the point cloud density of each second slice to obtain the first pier point cloud, slice the first pier point cloud along the third direction to obtain a third slice, obtain the filtered cross-sectional size according to the third slice, and obtain the second pier point cloud through bounding box filtering, and segment and extract the third pier point cloud; S5, determine the cross-sectional profile of the pier based on the standard deviation of the bounding box size and the fitted circle; S6, for the different cross-sectional profiles of the piers determined in S5, slice the third pier point cloud along the fourth direction in the local coordinate system to obtain a fourth slice, calculate the centroid of the pier according to the point cloud of the fourth slice, and detect the verticality of the pier cross-sectional area by fitting the cross-sectional centroid.

[0007] The beneficial effects of the present invention are as follows: the method can fit a continuous and high-precision bridge pier axis by collecting a large amount of point cloud data, and adopts the centroid coordinates of all the point cloud slices of the bridge pier to fit the verticality of the bridge pier cross-sectional contours by the angle between the axis equation and the vertical direction, so that the measured data is more accurate; in addition, the present application proposes a segmentation algorithm for the bridge pier point cloud in the point cloud containing vegetation, ground and main beams, cap beams, tie beams and bridge piers of up to dozens of spans through point cloud registration, realizes the batch and automatic segmentation of the pier point cloud, realizes the automatic segmentation of the bridge pier point cloud in large-scale bridges, and realizes the batch detection of bridge piers. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a flow chart of a method for automatically detecting verticality of large quantities of bridge piers based on three-dimensional ground scanning according to an embodiment of the present application;

[0009] Figure 2 This is a flow chart showing another expression of the method for automated detection of verticality of large quantities of bridge piers based on three-dimensional ground scanning according to an embodiment of the present application. DETAILED DESCRIPTION

[0010] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0011] See Figure 1 , the present invention provides a technical solution:

[0012] Before describing in detail a method for automatically detecting verticality of large quantities of bridge piers based on three-dimensional ground scanning according to an embodiment of the present application, the following professional terms are explained:

[0013] Single-site cloud: This refers to point cloud data acquired from a fixed scanning station (i.e., the location of a laser scanner). During 3D laser scanning, the laser scanner scans an object from a specific location, acquiring point cloud data of the object's surface from that location's perspective. This forms a single-site cloud.

[0014] Bounding box: It is a minimum geometric body used to enclose an object or point cloud. The bounding box can be generated based on the geometric model of the object.

[0015] Perpendicularity calculation: Calculate the angle or offset by the difference between the slope of the axis equation and the theoretical vertical direction.

[0016] In some embodiments, combined Figure 1-Figure 2 It is understood that the automated detection method for the verticality of large quantities of bridge piers based on ground 3D scanning includes the following steps:

[0017] S1. The user places the 3D laser scanner next to the bridge pier according to the incident angle limitation of the terrestrial laser scanner, for example, maintaining a safe distance of 0.5-1.5 meters between the scanner and the pier surface; and places target balls on the pier, for example, by fixing them with a magnetic base, and placing the target balls in different areas of the pier.

[0018] Based on the arranged 3D laser scanners and target spheres, a single-site cloud is collected, and the target sphere point cloud within the single-site cloud is identified. The point cloud is then registered using the target sphere to obtain an overall point cloud model of the bridge and its surrounding environment.

[0019] S2. Segment the entire point cloud model to extract the bridge point cloud, specifically including the following steps:

[0020] S21. Segment the entire point cloud model into ground point cloud and ground point cloud using a cloth filtering algorithm.

[0021] It's worth noting that the stiffness coefficient d has a significant impact on fabric stiffness and the degree of contact between the fabric simulation results and the ground. Fabric filtering algorithms are currently primarily used to process drone-mounted point clouds to obtain digital ground models. The point spacing is typically tens of centimeters, so a larger d value is used. In this application, a terrestrial 3D laser scanner is used to collect point cloud data, with millimeter-level point spacing. Therefore, the stiffness coefficient d needs to be dynamically adjusted based on the scenario to improve ground point cloud segmentation accuracy. In some preferred examples, d = 10r, where r is the scanner resolution (i.e., the point spacing at a range of 10m). The overall point cloud is segmented into a ground point cloud and an aboveground point cloud.

[0022] S21, the ground point cloud is divided into multiple clusters using the Euclidean clustering algorithm, and the maximum distance between adjacent clusters is preset. and the minimum number of point clouds within a cluster Segment the bridge point cloud.

[0023] In some examples, The value of is 0.5m, The value is 1 / 100 of the total number of point clouds. The ground point cloud is then divided into bridge point clouds and multiple vegetation point cloud clusters. The number of point clouds in each cluster is counted, and the clusters with the largest number of point clouds are bridge point clouds, where N is the number of bridges.

[0024] S3. Estimate the bridge path of the bridge, slice the bridge point cloud along the bridge path to obtain several first slices, obtain peak slices among the several first slices, extract the pier area point cloud from the bridge point cloud based on the peak slices, and establish a local coordinate system for the pier area point cloud. This specifically includes the following steps:

[0025] S31. Project the bridge point cloud onto the XOY plane to obtain a two-dimensional bridge point cloud.

[0026] S32. Use principal component analysis to determine the bridge's forward direction, and use a quadratic parabola to fit the centroid coordinates of the point cloud data in the two-dimensional bridge point cloud. , where the subscript mi is used to distinguish parameters, thus obtaining the rough bridge route , where a, b, and c are parameters. x is the horizontal coordinate value variable of the bridge route, and y is the vertical position value variable of the bridge route.

[0027] S33, the projected bridge point cloud (i.e., the two-dimensional bridge point cloud) is sliced along the rough bridge route according to the first slice spacing D. In some examples, the value of the first slice spacing D satisfies , It is the maximum width of the cap beam along the bridge direction.

[0028] Specifically, the bridge route length I in the area where the bridge point cloud is located is divided into intervals according to the spacing D. I is calculated according to the following formula:

[0029]

[0030] Where, and Refers to the minimum and maximum values of the centroid coordinates respectively. Then, the bridge route is obtained The coordinates of each dividing point ,in The point cloud between adjacent equally divided points is divided by the straight line passing through the equally divided points. The equation of the straight line passing through the i-th equally divided point is shown as follows.

[0031]

[0032] The number of point clouds in the first slice after segmentation is counted. The position of the first slice with the largest number of point clouds in the statistical graph, which corresponds to the position of the bridge pier, is called the peak slice. The peak slice position center point is used to determine the tangent direction of the route. The point cloud in the area is used as the point cloud of the pier area at that location , to extract the pier area point cloud from the bridge point cloud .

[0033] S35, based on the local coordinate system to determine the point cloud of the pier area , establish the local coordinate system of the pier , with the center of mass in the XOY plane As the coordinate origin , take the straight line perpendicular to the rough bridge path equation through the centroid as the y-axis, and the tangent through the centroid as the x-axis. The conversion formula to the global coordinate system XOY is as follows:

[0034]

[0035] Where, is the angle between the global coordinate system and the local coordinate system, .

[0036] S4. Slicing along the second direction in the local coordinate system to obtain a plurality of second slices, calculating the point cloud density of each second slice to obtain a first pier point cloud, slicing the first pier point cloud along the third direction to obtain a third slice, and performing bounding box filtering to segment and extract the third pier point cloud; specifically comprising:

[0037] S41, slicing along the second direction in the local coordinate system of the point cloud of the pier area, where the second direction is the y-axis direction, to obtain a plurality of second slices. The spacing is preferably less than 1 / 2 of the minimum cross-sectional dimension of the pier, in order to completely extract the point cloud of the first pier. The second slice, for The maximum and minimum values in the , the number of point clouds in each second slice is , so the average number of point clouds in the second slice is .Pick The point cloud of the second slice and its adjacent slice are merged into the first pier point cloud.

[0038] S43. Slice the point cloud of the first pier along a third direction, where the third direction is the z-axis direction of the local coordinate system, to obtain a plurality of third slices, and project the point clouds of the third slices onto the XOY plane.

[0039] Use a square frame to fit the edge of the point cloud projected by the third slice, and record the size of the square frame corresponding to the point cloud of the third slice , and the centroid coordinates corresponding to the square box , the subscript ri is used to distinguish parameters, where is the average z value of all points in the third slice, are the centroid coordinates of the squares enclosed in the third slice respectively. Then, the square sizes obtained by fitting all the third slices are counted, and the square size with the largest probability is used as the filter section size of the pier column. Due to the influence of the verticality of the pier, the size of the square frame is Increase tolerance Extract the complete point cloud of the second pier, and the final filter square box size is The height direction of the square bounding box uses the fitted line of the centroid corresponding to the square size with the maximum probability. After applying bounding box filtering, the main beam point cloud still exists within the square box where the pier is located. Cluster segmentation is used to extract the filtered point cloud of the third pier. For ease of explanation, this is defined as the third pier point cloud.

[0040] S5. According to the filter section size The cross-sectional profile of the pier is determined based on the size of the bounding box and the standard deviation of the fitted circle. The cross-sectional type of the pier is determined specifically by the following formula:

[0041] Using the first condition in the formula and The relationship between the rectangular cross-section pier and the square or circular cross-section pier is distinguished. Then, according to the second condition and The relationship between the square section and the circular section pier is distinguished. Specifically, if The bridge pier is a rectangular cross-section bridge pier, if it satisfies The bridge pier is a square or circular pier, and then judge: if it satisfies , then the bridge pier is a square pier, if it satisfies , then the bridge pier is a circular bridge pier. As shown in the following formula:

[0042]

[0043] in It is the difference between the length and width of the section, used to distinguish between rectangular sections and square sections, and is generally taken as 0.1m. is the standard deviation of the maximum z-value slice point cloud circle fitting for the sub-pier point cloud sliced along the Z axis, and is the standard deviation threshold for distinguishing circular sections from square sections, which is taken as 0.1 in some examples.

[0044] In this way, according to the relevant parameters in the pier point cloud segmentation algorithm, that is, the size of the bounding box , and the fitting standard deviation, to achieve the discrimination of circular, square and rectangular bridge pier cross sections. Compared with the existing technology, which does not identify bridge piers with different cross sections, the accuracy of this application is higher.

[0045] S6. For the different pier cross-sectional profiles determined in S5, slice the third pier point cloud along a fourth direction in the local coordinate system to obtain a fourth slice, calculate the centroid of the pier based on the point cloud of the fourth slice, and fit the cross-sectional centroid to detect the verticality of the pier cross-sectional area.

[0046] It is understandable that the method of this application can fit a continuous, high-precision bridge pier axis by collecting a large amount of point cloud data, and uses the centroid coordinates of all the point cloud slices of the bridge pier to fit the verticality of the different bridge pier cross-sectional contours by the angle between the axis equation and the vertical direction, making the measured data more accurate. In addition, this application proposes a segmentation algorithm for the bridge pier point cloud in the point cloud that contains vegetation, ground, and up to dozens of spans of main beams, cap beams, tie beams, and bridge piers through point cloud registration, realizing batch and automated segmentation of pier point clouds, realizing automatic segmentation of bridge pier point clouds in large-scale bridges, and realizing batch detection of bridge piers. Compared with the existing technology, which does not perform batch extraction of pier point clouds, but targets single bridge piers, and the target type is high pier detection method, the effect is better.

[0047] Next, S6 is described in detail based on some exemplary embodiments.

[0048] First example, for a square bridge pier with a complete point cloud:

[0049] S61: Slice the point cloud of the third bridge pier along a fourth direction (in this example, the fourth direction is the z-axis slice in the local coordinate system) to obtain a plurality of fourth slices. Project the point clouds of the fourth slices onto the XOY plane to obtain a two-dimensional contour point cloud.

[0050] S62, the point cloud of the fourth slice after projection is taken as The square grid is divided and the edge lines of the piers are fitted. .

[0051] Specifically, the grid size is , Calculate according to the following formula:

[0052]

[0053] in Grid size factor, in some examples .

[0054] Then, the minimum number q of point clouds inside each grid and the standard deviation of the fitted line are used Eliminate unqualified grid point clouds in the edge point cloud, and the point cloud inside each grid The straight line fitting method uses RANSAC and records the slope of the fitted line in each grid and intercept , is the intercept on the y-axis. Where q can be 5, You can take 0.001. Then compare the intercept of each grid fitting line. The internal point cloud of the grid is merged into a point cloud of a side line, and the side line equation is fitted using RANSAC to obtain the side line equation of each pier section. .in, It is the threshold of the intercept of the grid point cloud fitting line on the same edge line on the y-axis. .

[0055] S63. Equations of multiple edges Solve the two points to get the coordinates of several intersection points , where i is a positive integer and j is also a positive integer, Indicates the i The fourth slice j intersection points, and the edge equation The intersection of two straight lines that meet the requirements is not solved. To prevent parallel lines from intersecting, the slope threshold can be set to 2.

[0056] S64, using the solved edge intersection coordinates Calculate centroid coordinates The subscript m is used to distinguish parameters. Indicates the i The centroid coordinates of the fourth slice, wherein, , The least squares fitting method is used to fit the centroid of each fourth slice of the point cloud to obtain the axis of the bridge pier. , A, B, C, and E are calculated coefficients, and x, y, and z are the coordinate values of the coordinate system corresponding to the pier axis in three directions; thus, verticality detection is achieved based on the pier axis:

[0057] S65. Calculate the pier offset angle and pier top displacement (M is the design height of the pier):

[0058] , displacement of pier top .

[0059] In the second embodiment, for a square bridge pier with missing point clouds, step S631A is performed after step S63.

[0060] S631A: The centroid coordinates of the point cloud of the pier section are used as the initial circle center coordinates , where the subscript c is used to distinguish parameters and calculate the distance from the initial center coordinate to the three edges , and The variance between Minimum is used as the objective function, which is shown in the following formula:

[0061]

[0062] in, for The mean of .

[0063] Continuously iterate to determine the centroid coordinates of the pier column section , the subscript l is used to distinguish the parameter and the corresponding inscribed circle radius ,and ,in are the coordinates of the circle center when the iteration is completed The distance to the three sides. The coordinates of the center of the inscribed circle of each fourth slice are used as the centroid coordinates of the fourth slice contour, and a straight line is fitted to calculate the verticality of the bridge pier.

[0064] As can be understood, a method for calculating the cross-sectional profile of rectangular and square piers with complete point clouds is proposed. The four side lines of the pier are obtained, and the coordinates of the pier corner points are calculated by finding the intersection points between them. The coordinates of the cross-sectional centroid are then calculated based on the average of the coordinates of the intersection points between the pier's cross-sectional side lines. Finally, the least squares method is used to fit the centroid coordinates to obtain the axis equation. Finally, the angle between the axis equation and the vertical is calculated to calculate the pier's verticality. This method, based on all slices of a pier, obtains the axis equation by fitting the centroid coordinates, and calculates the verticality using the angle between the axis equation and the vertical. This method achieves higher accuracy and reduces random errors compared to the conventional method of calculating vertical height using the two centroid coordinates of the bottom and top.

[0065] In some embodiments, for a rectangular bridge pier with missing point clouds, step S631B is performed after step S63:

[0066] First, in an ideal geometric model, let the intersection of the two diagonals of the rectangular section be A and B, and use them as the basis to draw the circumscribed circle of the rectangle. The radius of the circle is , the coordinates of the circle center are When the circle passes through the first side line of the rectangle and the third side line of the rectangle, the minimum coordinate point in the Y-axis direction of the corresponding point cloud data is When , we can establish two circumscribed circle equations, which are circle 1 and circle 3 equations. If the length of the first side is equal to the length of the third side, that is Then the coordinates of the center of the circle are With the centroid of the rectangular cross section Total overlap.

[0067] However, in practice, due to construction errors and the influence of the scanner's incident angle, The center coordinates deviate from the centroid. After research, it was found that if the circumscribed circle must pass through A, B and a point C on the third side (and C is only allowed to move in the Y-axis direction), the offset of the center coordinates is only reflected in the Y-axis direction. Therefore, The coordinates of the center of the final rectangular cross-section circumscribed circle are the centroid coordinates of the actual rectangular cross-section. Finally, the centroid coordinates of the cross-sections are extracted layer by layer along the height of the pier. The centroid coordinates of each slice are fitted to obtain the pier axis equation. The verticality of the pier can then be calculated through the verticality calculation.

[0068] In some embodiments, for a circular cross-section bridge pier, S6 specifically includes the following steps:

[0069] S61C: Slice the point cloud of the third pier along the z-axis to obtain the fifth slice, and project the fifth slice onto the XOY plane.

[0070] S62C: The three-point circle method is used to solve the center coordinates and radius of the projected two-dimensional point cloud, and the projected point clouds of all fifth slices are traversed in sequence.

[0071] S63C: Radius Perform probability statistics to obtain the radius with the maximum probability and its corresponding center coordinates Then, As the center of the circle, the outer diameter is , the inner diameter is , a torus with a height equal to the thickness of the fifth slice, and the point cloud outside the torus is deleted. In order to allow for errors and ensure the integrity of the pier point cloud, a value of 5 mm can be used.

[0072] S64C: Fit the centroid coordinates of each fifth slice to obtain the pier axis equation, thereby calculating the pier verticality.

[0073] It can be seen that the embodiment of the present application can calculate the verticality of rectangular and square piers with missing single-sided point clouds based on the method of adopting inscribed circle iteration and circumscribed circle iteration; and can also realize the verticality calculation for cylindrical piers, so that the verticality calculation of square piers with complete point clouds, missing single-sided point clouds, and cylindrical piers can be realized. Compared with the existing technology, which can only calculate the verticality of square piers with complete point clouds, the effect is better. Therefore, compared with the problem of not being able to calculate the verticality of piers when facing piers with missing point clouds, the present application can realize the verticality calculation of square piers with complete point clouds, missing single-sided point clouds, and cylindrical piers, and has wider applicability.

[0074] The foregoing description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Rather, the present invention can be used in various other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the appended claims.

Claims

1. A method for automatically detecting the verticality of large quantities of bridge piers based on ground three-dimensional scanning, characterized in that: The steps include: S1. Collecting a single-site cloud using a 3D laser scanner and a target sphere, identifying a target sphere point cloud within the single-site cloud, and obtaining an overall point cloud model of the bridge and its surrounding environment through target sphere point cloud registration; S2. Segmenting the entire point cloud model to obtain a bridge point cloud; S3. Estimating a bridge route of the bridge, slicing the bridge point cloud along the bridge route to obtain a plurality of first slices, obtaining peak slices among the plurality of first slices, extracting a pier region point cloud from the bridge point cloud based on the peak slices, and establishing a local coordinate system for the pier region point cloud; S4. Slicing the local coordinate system along the y-axis to obtain a plurality of second slices, calculating the point cloud density of each of the second slices to obtain a first pier point cloud, slicing the first pier point cloud along the z-axis of the local coordinate system to obtain a third slice, obtaining a filtered cross-sectional size based on the third slice, performing bounding box filtering to obtain a second pier point cloud, and extracting a third pier point cloud by Euclidean clustering. The S4 specifically includes the following steps: S42: Slice along the y-axis in the local coordinate system to obtain a plurality of second slices, and obtain the number of point clouds in each second slice. And the average number of point clouds in the second slice ,Pick and merging the point clouds of the second slice and its adjacent point clouds into a single point cloud of the first pier; S43, slicing the first pier point cloud along the Z-axis direction of the local coordinate system to obtain a plurality of third slices, projecting the point clouds of the third slices onto the XOY plane; fitting the edges of the point clouds projected by the third slices with a square frame, and recording the size of the square frame corresponding to the point clouds of the third slices as , and the centroid coordinates corresponding to the square box , the subscript ri is used to distinguish parameters; the square sizes of the square boxes obtained by fitting all the third slices are counted, and the square size with the largest probability is used as the filter section size of the pier column. , wherein the height direction of the bounding box adopts the fitting straight line of the centroid corresponding to the maximum probability square size; the size of the square box is respectively Increase tolerance Extract the complete point cloud of the second pier, and the final filter square box size is ; S44, after filtering by the bounding box, extracting the point cloud of the third pier by clustering segmentation; S5. Determine the cross-sectional profile of the bridge pier based on the size of the bounding box and the standard deviation of the fitted circle; The S5 specifically includes: If satisfied The bridge pier is a rectangular cross-section bridge pier, if it satisfies The bridge pier is a square or circular pier, and then judge: If satisfied , then the bridge pier is a square bridge pier, if it satisfies , then the bridge pier is a circular bridge pier; in, is the difference between the length and width of the section, is the standard deviation of the maximum z-value slice point cloud circle fitting for the third pier point cloud along the Z axis, is the standard deviation threshold for distinguishing circular and square cross sections; S6. For the different pier cross-sectional profiles determined in S5, slice the third pier point cloud along the z-axis in the local coordinate system to obtain a fourth slice, calculate the centroid of the pier based on the point cloud of the fourth slice, and fit the cross-sectional centroid to detect the verticality of the pier cross-section.

2. The method for automatically detecting verticality of large quantities of bridge piers based on three-dimensional ground scanning according to claim 1 is characterized in that: The S2 specifically includes: S21, segmenting the overall point cloud model into ground point cloud and ground point cloud using a cloth filtering algorithm; S22. Use a Euclidean clustering algorithm to segment the ground point cloud into multiple clusters, and segment the bridge point cloud according to preset parameters.

3. The method for automatically detecting verticality of large quantities of bridge piers based on three-dimensional ground scanning according to claim 2 is characterized in that: The S3 specifically includes the following steps: S31, projecting the bridge point cloud onto the XOY plane to obtain a two-dimensional bridge point cloud; S32, analyzing the forward direction of the bridge and fitting the centroid coordinates of the point cloud data in the two-dimensional bridge point cloud , the subscript mi is used to distinguish the parameters, thus obtaining the relationship describing the bridge route , where a, b, and c are all parameters, x is the independent variable coordinate value of the bridge route in the horizontal direction, and y is the position coordinate of the bridge route in the vertical direction; S33, slicing the two-dimensional bridge point cloud along the bridge route according to the set first slice spacing D. Slicing in the direction of to obtain a plurality of first slices; S34, counting the number of point clouds of the first slice after segmentation, the first slice position with the largest number of point clouds is the peak slice, and the peak slice position center point route tangent direction is used to calculate the number of point clouds of the first slice after segmentation. The point cloud in the area is used as the point cloud of the pier area ,in, The maximum width of the cap beam along the bridge direction; S35, establishing the local coordinate system of the bridge pier corresponding to the two-dimensional bridge point cloud The subscript qi is used to distinguish the parameters, with the coordinates of the center of mass in the XOY plane As the coordinate origin, the centroid point The straight line perpendicular to the bridge route is used as the y-axis, and the line passing through the centroid point The tangent line of is used as the x-axis.

4. The method for automated detection of verticality of large quantities of bridge piers based on three-dimensional ground scanning according to claim 3 is characterized by: The S6 specifically includes: S61, slicing the point cloud of the third pier along the z-axis in the local coordinate system to obtain a plurality of fourth slices, and projecting the point clouds of the fourth slices onto the XOY plane to obtain a two-dimensional contour point cloud; S62, segmenting the projected point cloud of the fourth slice using a square grid, and fitting the equations of the multiple side lines of the pier ; S63, solving the equations of the plurality of side lines in pairs to obtain the coordinates of several intersection points , where i is a positive integer and j is also a positive integer, Indicates the i The fourth slice j intersection points; S64, using the coordinates of each of the intersection points after solution Calculate centroid coordinates , using the least squares fitting method to fit the centroid coordinates of each point cloud of the fourth slice , we get the relationship between the pier axis and , A, B, C, and E are all parameters, and x, y, and z are the coordinate values of the coordinate system corresponding to the axis of the pier in three directions; S65. Calculate the pier offset angle and pier top displacement .

5. The method for automated detection of verticality of large quantities of bridge piers based on three-dimensional ground scanning according to claim 4 is characterized in that: For square bridge piers with missing point clouds, perform S631A after step S63: The centroid coordinates of the point cloud of the pier cross section is the initial center coordinate, where subscript c is used to distinguish parameters, and the distance from the initial center coordinate to any three side lines is calculated. and the three edges The variance between As the objective function, iterate the objective function to determine the centroid coordinates of the pier column section , where the subscript l Used to distinguish parameters and the radius of the inscribed circle corresponding to the pier section ,and , where are respectively the distances from the center coordinates to the three sides when the iteration is completed; the center coordinates of the inscribed circle of each fourth slice are used as the centroid coordinates of the fourth slice contour.

6. The method for automatically detecting verticality of large quantities of bridge piers based on three-dimensional ground scanning according to claim 4 is characterized in that: For rectangular bridge piers with missing point clouds, perform S631B after step S63; S631B includes: taking the intersection of the two diagonals of the rectangular cross section of the rectangular cross section of the bridge pier as a reference, making a rectangular circumscribed circle, obtaining the equations of the two corresponding circumscribed circles, and the radii of the two circumscribed circles are r l1 , r l3 The coordinates of the circle center are ,when When the center coordinates With the centroid of the rectangular cross section overlap; when When, based on The center coordinates of the circle ,Will As the coordinates of the center of the circumscribed circle of the rectangular cross section, the coordinates of the center of the circumscribed circle are the coordinates of the centroid of the actual rectangular cross section.

7. The method for automated detection of verticality of large quantities of bridge piers based on three-dimensional ground scanning according to claim 3 is characterized by: For circular cross-section bridge piers, S6 specifically includes the following steps: S61C, slicing the bridge pier point cloud along the z-axis to obtain a fifth slice, and projecting the slice onto the XOY plane; S62C, using a three-point circle method to solve the center coordinates and radius of the projected two-dimensional point cloud, and traversing all the projected point clouds of the fifth slice in sequence; S63C, perform probability statistics on the radius of the center of the circle to obtain the radius with the maximum probability and its corresponding center coordinates , then, with As the center of the circle, the outer diameter is , inner diameter is , a torus with a height equal to the thickness of the fifth slice, deleting the point cloud outside the torus; wherein is the allowable error; S64C. Fit the centroid coordinates of each of the fifth slices to obtain the pier axis equation, thereby calculating the verticality of the pier.

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