Quantitative method and device for shape of ditch head overhang based on three-dimensional laser scanning point cloud

Abstract

This invention relates to a method and apparatus for quantifying the morphology of a gully head overhang based on three-dimensional laser scanning point clouds, belonging to the field of gully head measurement technology. The method includes: performing a 3D omnidirectional three-dimensional scan of the target gully head using a three-dimensional laser scanning system to acquire three-dimensional scanning point cloud data of the target gully head overhang; segmenting the three-dimensional scanning point cloud data of the target gully head overhang by rotating slices to obtain rotating slice planar data of the target gully head overhang; performing data shrinkage fitting on the rotating slice planar data of the target gully head overhang to obtain rotating slice fitted data of the target gully head overhang; extracting evaluation indicators of the target gully head overhang based on the rotating slice fitted data of the target gully head overhang; and quantifying the stability of the target gully head overhang based on the evaluation indicators, which is beneficial for refining the indicator features and obtaining more accurate stability evaluation results.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gully head measurement, and in particular to a gully head overhanging body form quantification method and device based on three-dimensional laser scanning point clouds. BACKGROUND

[0002] Soil is the core component of the terrestrial ecosystem and the most basic natural resource for human survival and development. Soil erosion is a global concern, which refers to the process of soil being detached from its parent material and transported and deposited to other locations under the action of external forces such as wind, water, gravity, and freeze-thaw. It can cause major environmental and economic problems such as land degradation, geological disasters, and water pollution. Gully erosion is the most severe type of soil erosion, and the sediment yield caused by the collapse and instability of overhanging soil on the gully head can reach 94% of the total regional sediment yield. This process is the most significant feature of gully erosion. However, the gully head form is extremely complex, making it difficult to quantify the gully head overhanging body form, hindering the evaluation of gully head structure stability, and limiting the research and management of gully erosion. Therefore, a gully head overhanging body form quantification method is needed to effectively evaluate the gully head structure stability. SUMMARY

[0003] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present application provides a gully head overhanging body form quantification method and device based on three-dimensional laser scanning point clouds, which solves the technical problem of difficulty in quantifying the gully head overhanging body form in the prior art.

[0004] In order to achieve the above-mentioned purpose, the main technical solutions adopted by the present application include:

[0005] The first aspect of the embodiment of the present application provides a gully head overhanging body form quantification method based on three-dimensional laser scanning point clouds.

[0006] The gully head overhanging body form quantification method based on three-dimensional laser scanning point clouds proposed by the embodiment of the present application includes:

[0007] The target gully head is scanned in all directions by a three-dimensional laser scanning system to obtain three-dimensional scanning point cloud data of the target gully head, and three-dimensional scanning point cloud data of the target gully head overhanging body is extracted from the three-dimensional scanning point cloud data of the target gully head;

[0008] The three-dimensional scanning point cloud data of the target gully head overhanging body is divided by rotating slicing to obtain rotating slice plane data of the target gully head overhanging body;

[0009] The rotating slice plane data of the target gully head overhanging body is subjected to data shrinkage fitting to obtain rotating slice fitting data of the target gully head overhanging body;

[0010] extracting evaluation indexes of the target overhang based on the rotation slice fitting data of the target overhang;

[0011] quantitatively evaluating the stability of the target overhang based on the evaluation indexes of the target overhang.

[0012] In some examples, the evaluation indexes include: overhang height, overhang depth and overhang area corresponding to each rotation slice;

[0013] The extracting of the evaluation indexes of the target overhang based on the rotation slice fitting data of the target overhang includes:

[0014] extracting the overhang height, the overhang depth and the overhang area corresponding to each rotation slice based on the rotation slice fitting data of the target overhang and the index extraction model.

[0015] In some examples, the index extraction model includes an overhang height extraction model, an overhang depth extraction model and an overhang area extraction model.

[0016] The extracting of the overhang height, the overhang depth and the overhang area corresponding to each rotation slice based on the rotation slice fitting data of the target overhang and the index extraction model includes:

[0017] extracting the overhang height corresponding to each rotation slice based on the rotation slice fitting data of the target overhang and the overhang height extraction model.

[0018] extracting the overhang depth corresponding to each rotation slice based on the rotation slice fitting data of the target overhang and the overhang depth extraction model.

[0019] extracting the overhang area corresponding to each rotation slice based on the rotation slice fitting data of the target overhang and the overhang area extraction model.

[0020] In some examples, the quantitatively evaluating of the stability of the target overhang based on the evaluation indexes of the target overhang includes:

[0021] establishing an overhang stability quantitative evaluation model based on the evaluation indexes of the target overhang and the distance from the original point cloud to the rotation axis in each rotation slice;

[0022] quantitatively evaluating the stability of the target overhang based on the evaluation indexes of the target overhang and the overhang stability quantitative evaluation model.

[0023] In some examples, the three-dimensional scanning point cloud data of the target gully head overhang is segmented by rotating the slices to obtain the rotating slice plane data of the target gully head overhang, including:

[0024] The overhang point cloud is rotated by taking the three-dimensional coordinate system origin as the axis and taking the z-axis as the rotating axis to obtain the rotating slice plane data of the target gully head overhang; wherein each rotating slice has a predetermined angle.

[0025] In some examples, the rotating slice plane data of the target gully head overhang is subjected to data contraction fitting to obtain the rotating slice fitting data of the target gully head overhang, including:

[0026] The rotating slice plane data of the target gully head overhang is compressed to the plane where the intermediate angle value of the predetermined angle to obtain compressed plane data;

[0027] The compressed plane data is subjected to line fitting to obtain the rotating slice fitting data of the target gully head overhang.

[0028] In some examples, the three-dimensional scanning point cloud data of the target gully head overhang is segmented by rotating the slices to obtain the rotating slice plane data of the target gully head overhang, including:

[0029] N spherical targets are arranged in the to-be-scanned region:

[0030] The regions where the N spherical targets are located are scanned multiple times from different angles to obtain multiple topographic point clouds at different angles; wherein each topographic point cloud covers at least one spherical target;

[0031] The three-dimensional scanning point cloud data of the target gully head is obtained by splicing the point clouds based on the center coordinates of the spherical targets in each topographic point cloud.

[0032] The second aspect of the embodiment of the application provides a gully head overhang form quantification device based on three-dimensional laser scanning point clouds, including:

[0033] A data acquisition unit is configured to perform omnidirectional three-dimensional scanning on a target gully head based on a three-dimensional laser scanning system, acquire three-dimensional scanning point cloud data of the target gully head, and extract three-dimensional scanning point cloud data of a target gully head overhang from the three-dimensional scanning point cloud data of the target gully head;

[0034] A data segmentation unit is configured to segment the three-dimensional scanning point cloud data of the target gully head overhang by rotating the slices to obtain the rotating slice plane data of the target gully head overhang;

[0035] a data fitting unit, configured to perform data shrinkage fitting on the rotation slice plane data of the target gully head overhang to obtain rotation slice fitting data of the target gully head overhang;

[0036] an index extraction unit, configured to extract evaluation indexes of the target gully head overhang based on the rotation slice fitting data of the target gully head overhang;

[0037] a quantitative evaluation unit, configured to quantitatively evaluate the stability of the target gully head overhang based on the evaluation indexes of the target gully head overhang.

[0038] A computer readable storage medium is provided in a third aspect of the embodiments of the present application, and the computer readable storage medium stores a gully head overhang form quantification program based on three-dimensional laser scanning point clouds. When the gully head overhang form quantification program based on three-dimensional laser scanning point clouds is executed by a processor, the gully head overhang form quantification method based on three-dimensional laser scanning point clouds in the first aspect is implemented.

[0039] An electronic device is provided in a fourth aspect of the embodiments of the present application, and the electronic device includes a memory, a processor, and a gully head overhang form quantification program based on three-dimensional laser scanning point clouds stored in the memory and executable on the processor. When the gully head overhang form quantification program based on three-dimensional laser scanning point clouds is executed by the processor, the gully head overhang form quantification method based on three-dimensional laser scanning point clouds in the first aspect is implemented.

[0040] The gully head overhang form quantification method based on three-dimensional laser scanning point clouds includes: performing omnidirectional three-dimensional scanning on a target gully head based on a three-dimensional laser scanning system, acquiring three-dimensional scanning point cloud data of the target gully head, and extracting three-dimensional scanning point cloud data of a target gully head overhang from the three-dimensional scanning point cloud data of the target gully head; performing data segmentation on the three-dimensional scanning point cloud data of the target gully head overhang in a rotation slice manner to obtain rotation slice plane data of the target gully head overhang; performing data shrinkage fitting on the rotation slice plane data of the target gully head overhang to obtain rotation slice fitting data of the target gully head overhang; extracting evaluation indexes of the target gully head overhang based on the rotation slice fitting data of the target gully head overhang; and quantitatively evaluating the stability of the target gully head overhang based on the evaluation indexes of the target gully head overhang. In the present application, the point cloud data of the gully head is acquired omnidirectionally, the point cloud data is subjected to rotation slicing, the evaluation indexes corresponding to each slice are extracted, and then the stability of the target gully head overhang is quantitatively evaluated based on the evaluation indexes corresponding to each slice, which is beneficial to more detailed index features and more accurate stability evaluation results. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1A three-dimensional laser scanning point cloud based on a ditch head suspended body form quantification method flow chart provided for an embodiment of the present application is shown in the figure.

[0042] Figure 2 A target ball arrangement schematic diagram provided for an embodiment of the present application is shown in the figure.

[0043] Figure 3 A suspended body extraction schematic diagram provided for an embodiment of the present application is shown in the figure.

[0044] Figure 4 A point cloud rotation slicing schematic diagram provided for an embodiment of the present application is shown in the figure.

[0045] Figure 5 A point cloud rotation slicing data contraction schematic diagram provided for an embodiment of the present application is shown in the figure.

[0046] Figure 6 A suspended body evaluation index schematic diagram provided for an embodiment of the present application is shown in the figure.

[0047] Figure 7 A test verification field distribution schematic diagram provided for an embodiment of the present application is shown in the figure.

[0048] Figure 8 A three-dimensional laser scanning point cloud based on a ditch head suspended body form quantification device structure schematic diagram provided for an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0049] In order to better explain the present application, in order to facilitate understanding, the present application is described in detail by specific embodiments in combination with the accompanying drawings.

[0050] The three-dimensional laser scanning point cloud based on a ditch head suspended body form quantification method provided by the embodiment of the present application is used to solve the problem of ditch head suspended body form quantification difficulty, the point cloud data of the ditch head is obtained in all directions, the point cloud data is rotated and sliced, the evaluation indexes corresponding to each slice are extracted, and then the stability of the target ditch head suspended body is quantitatively evaluated based on the evaluation indexes corresponding to each slice, which is beneficial to more detailed index characteristics and more accurate stability evaluation results.

[0051] In order to better understand the above technical solutions, the exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a clearer, more thorough understanding of the present application and to enable the scope of the present application to be fully conveyed to those skilled in the art.

[0052] Figure 1 A three-dimensional laser scanning point cloud based on a ditch head suspended body form quantification method flow chart provided for an embodiment of the present application is shown in the figure. Figure 1As shown, the method for quantifying the shape of a hanging body at a gully head based on three-dimensional laser scanning point cloud proposed in the embodiment of the application comprises the following steps:

[0053] Step 100, performing omnidirectional three-dimensional scanning on the target gully head based on a three-dimensional laser scanning system, acquiring three-dimensional scanning point cloud data of the target gully head, and extracting three-dimensional scanning point cloud data of the hanging body at the target gully head from the three-dimensional scanning point cloud data of the target gully head;

[0054] Step 110, performing data segmentation on the three-dimensional scanning point cloud data of the hanging body at the target gully head in a rotating slice manner to obtain rotating slice plane data of the hanging body at the target gully head;

[0055] Step 120, performing data shrinkage fitting on the rotating slice plane data of the hanging body at the target gully head to obtain rotating slice fitting data of the hanging body at the target gully head;

[0056] Step 130, extracting evaluation indexes of the hanging body at the target gully head based on the rotating slice fitting data of the hanging body at the target gully head;

[0057] Step 140, quantitatively evaluating the stability of the hanging body at the target gully head based on the evaluation indexes of the hanging body at the target gully head.

[0058] In the present exemplary embodiment, the three-dimensional laser scanning system can adopt a pulsed three-dimensional laser scanner. The pulsed three-dimensional laser scanner has a transmission level of 3R (IEC 60825-1) level, can emit green laser with a wavelength of 532 nm, and has a scanning distance of 300 m and 134 m at 90% and 18% reflectivity, respectively, and a scanning speed of 50,000 points / s. Within a scanning range of 0-50 m, the laser spot diameter is 4.5 mm, and the scanning point spacing is less than 1 mm. The single-point point measurement accuracy and single-scan distance accuracy of the scanner are 6 mm and 4 mm, respectively, the model surface accuracy is 2 mm, the target ball scanning accuracy is 2 mm, and the horizontal and vertical angle accuracies are both 12″. In addition, the dynamic dual-axis compensation range and accuracy are ±5′ and 1.5″, respectively, and the dynamic dual-axis compensation resolution is 1″. The parameters of the above-mentioned pulsed three-dimensional laser scanner are only examples, and other suitable pulsed three-dimensional laser scanners can also be used in the present application.

[0059] In this exemplary embodiment, the topographic point cloud obtained by a three-dimensional laser scanner deployed at a single location may have data missing due to object occlusion. Generally, the target should be scanned from multiple angles (by setting up the instrument multiple times) and then the point clouds obtained from multiple scans are stitched together to finally obtain a complete topographic point cloud. Therefore, target balls can be used to calibrate the spatial position of the target topographic point cloud. The registration device supporting this terrestrial three-dimensional laser scanner system is the target ball, with a circular base radius of 0.05 m and a target ball radius of 0.075 m. Among them, target balls with other appropriate radii can also be used.

[0060] Figure 2 FIG. is a schematic diagram of the target ball layout provided by an embodiment of the present invention. As Figure 2 shown, after selecting the gully head overhang area (hereinafter collectively referred to as the research area), 4 unchanged positions (such as firmly embedded cement piles) are arranged or found outside the upper, lower, left, and right boundaries of the research area, and 4 target balls are respectively fixed at the corresponding positions. Subsequently, the laser three-dimensional scanner is installed and arranged multiple times at a selected position in front of the research area (such as Figure 2 in (b)) to obtain the point cloud of the research area. At the same time, the height of the tripod can also be adjusted according to the actual situation to ensure that a complete point cloud of the research area is obtained. Generally, the height range for setting up the instrument can be from 0.5 m to 2 m. When scanning the research area, the 4 target balls in and around the research area need to be included in the scanning range. To improve the scanning efficiency, the scanning accuracy can be set before scanning the research area. When the scanner is less than 20 m away from the research area, general resolution or high resolution can be selected, and when it is more than 20 m away, high resolution or ultra-high resolution can be used.

[0061] In some examples, the all-round three-dimensional scanning of the target gully head based on the three-dimensional laser scanning system to obtain the three-dimensional scanning point cloud data of the target gully head includes:

[0062] Setting N spherical targets in the area to be scanned:

[0063] Scanning the area where the N spherical targets are located from different angles multiple times to obtain multiple topographic point clouds at different angles; among them, each topographic point cloud covers at least one spherical target;

[0064] Based on the central coordinates of the spherical targets in each topographic point cloud, the point clouds are stitched together to obtain the three-dimensional scanning point cloud data of the target gully head.

[0065] In this exemplary embodiment, the positions of the N spherical targets are the predetermined positions of the target gully head. The target gully head is scanned from different angles, but each scan includes at least one target. All point clouds are stitched together through the central coordinates of the targets to obtain a complete point cloud.

[0066] For example, for the The point cloud of the second scan ( ) No. The center coordinates of each target ball are numbered as follows: (Then the center coordinates of the four target spheres in the unstitched point cloud are) , , , The first scan will be... Import the point cloud data into Cyclone 6.0 software, manually select the surface points of each target sphere, and use the recognition tool to fit and calculate the coordinates of the center point of each target sphere. The operation procedure is as follows: import the scanned single point cloud data (.bin format) into Cyclone 6.0, select the surface points of the target sphere, and then select "Create Object → Fit to Cloud → Sphere Target". Enter the number in the pop-up window. The fitting process is then complete. Next, select the fitted target sphere and extract the coordinates of its center from the display interface in the lower left corner of the window. When identifying the target sphere's center coordinates, the coordinate names of each target sphere's center should match those of the point cloud. For example, if the highest target sphere is designated as number 1, then in any... The center coordinates of this target ball must be In addition, the input .bin format point cloud is converted to a common point cloud format (such as .las, .txt, .xyz) for output, at which point the various... and the corresponding target ball center coordinates , , , .

[0067] for Import the data into Cloudcompare 2.0 software to complete the stitching operation. Before stitching, you need to select the point cloud data as the reference. This application can... The operation process will be described using a benchmark example. , After importing into CloudCompare 2.0, select all, then choose "Tools→Registration→Align (Point pairspicking)". In the pop-up window, use the "Swap" button to... Switch to the "Reference" window ( After confirming in the "Aligned" window, enter the numbers sequentially at the top of the pop-up window. Coordinates of the center of the target ball , , , Enter the following commands sequentially at the bottom of the window. Target sphere coordinates , , , Select the "align" button in this window to complete the alignment. Rotate all point clouds. After rotating all point clouds, select... and all rotations Select "Edit → Merge" and confirm to complete the stitching. You will then obtain the complete point cloud of the study area. .

[0068] This application also allows for filtering of the point cloud data. Point cloud filtering is the process of removing irrelevant points acquired during scanning (such as removing vegetation points, ground feature points outside the study area, etc.), implemented in Terrasolid V15 software. This results in a complete point cloud of the study area. After importing, use the "Place Line" tool in the "Drawing" section of the "View1-Top" window to select the study area. Then, sequentially close the point cloud data, select the study area to draw, and import it again. In the import interface, select "Inside fence only" to complete the cropping of the study area data. Then, using the "Draw Vertical Section" and "Create Editable Model" tools in the right-hand toolbox, combined with expert experience, [the following was done / then / etc.]. All points were manually categorized, and the ground point categories were finally exported to form... Further processing will be carried out.

[0069] To facilitate subsequent data processing, a custom point cloud coordinate system needs to be defined first. The coordinate system is defined as the O-XYZ coordinate system. First, the top leftmost point of the trench head is defined as the origin O. The horizontal ray pointing from the top leftmost point to the top rightmost point is the X-axis, the Z-axis points vertically towards the zenith, and the Y-axis is determined by the right-hand rule of the coordinate system. The implementation method is to first calculate... The top left dot points to The horizontal ray at the top right point rotates counterclockwise to... The direction of the OX rays forms an angle with the OX rays. , The coordinates of the top left point Secondly, Points The coordinate translation is Finally, according to formula (1), the changed points are... Perform a rotation operation to obtain the final coordinates of each point. The set, named :

[0070] (1). In this way, the coordinate system can be established at a suitable position according to the point cloud shape, so as to facilitate subsequent index calculation.

[0071] The application provides a suspended body shape quantification method based on three-dimensional laser scanning point clouds of a ditch head, which comprises the following steps: performing omnidirectional three-dimensional scanning on a target ditch head based on a three-dimensional laser scanning system, acquiring three-dimensional scanning point cloud data of the target ditch head, and extracting three-dimensional scanning point cloud data of a suspended body of the target ditch head from the three-dimensional scanning point cloud data of the target ditch head; performing data segmentation on the three-dimensional scanning point cloud data of the suspended body of the target ditch head in a rotating slice manner to obtain rotating slice plane data of the suspended body of the target ditch head; performing data shrinkage fitting on the rotating slice plane data of the suspended body of the target ditch head to obtain rotating slice fitting data of the suspended body of the target ditch head; extracting evaluation indexes of the suspended body of the target ditch head based on the rotating slice fitting data of the suspended body of the target ditch head; and quantitatively evaluating the stability of the suspended body of the target ditch head based on the evaluation indexes of the suspended body of the target ditch head. In the application, the point cloud data of the ditch head is acquired omnidirectionally, the point cloud data is subjected to rotating slice, the evaluation indexes corresponding to each slice are extracted, and then the stability of the suspended body of the target ditch head is quantitatively evaluated based on the evaluation indexes corresponding to each slice, so that the index characteristics can be refined and a more accurate stability evaluation result can be obtained.

[0072] In some examples, the three-dimensional scanning point cloud data of the target ditch head is extracted to obtain the three-dimensional scanning point cloud data of the suspended body of the target ditch head, and the method comprises the following steps:

[0073] Based on the phase state of the suspended body, the rotating segmentation angle range of the target ditch head is determined.

[0074] Based on the rotating segmentation angle range, the shape of the target ditch head is segmented to obtain the suspended body.

[0075] In the example embodiment, Figure 3 a suspended body extraction schematic diagram is provided for the application embodiment. As shown in the figure, Figure 3 the bottom surface of the suspended body generally has a shape similar to a vertical variable-radius cylinder, so two vertical slice planes (slice start plane and slice end plane ) are used to extract the suspended body point cloud. First, a vertical rotation axis is selected near the center of the boundary points on both sides of the ditch head according to experience, the start plane is defined as a vertical plane passing through the vertical rotation axis and parallel to the X axis rotated counterclockwise by 10° around the Z axis, and the end plane is defined as a vertical plane passing through the vertical rotation axis and parallel to the X axis rotated clockwise by 10° around the Z axis. All points falling within the range of the two planes 160° are target gully head overhang point clouds .

[0076] A gully head overhang form quantification method based on three-dimensional laser scanning point clouds of the present application, comprising: based on a three-dimensional laser scanning system, performing omnidirectional three-dimensional scanning on a target gully head, obtaining three-dimensional scanning point cloud data of the target gully head, and extracting three-dimensional scanning point cloud data of the target gully head overhang from the three-dimensional scanning point cloud data of the target gully head; through the method of rotating slicing, performing data segmentation on the three-dimensional scanning point cloud data of the target gully head overhang, obtaining rotating slicing plane data of the target gully head overhang; based on the rotating slicing fitting data of the target gully head overhang, extracting evaluation indexes of the target gully head overhang; based on the evaluation indexes of the target gully head overhang, quantitatively evaluating the stability of the target gully head overhang. In this application, the point cloud data of the gully head is obtained omnidirectionally, the point cloud data is rotated and sliced, the evaluation indexes corresponding to each slice are extracted, and then the stability of the target gully head overhang is quantitatively evaluated based on the evaluation indexes corresponding to each slice, which is beneficial to more detailed index features and more accurate stability evaluation results.

[0077] In some examples, the evaluation indexes include: overhang height, overhang depth and overhang area corresponding to each rotating slice;

[0078] The evaluation index extraction of the target gully head overhang based on the rotating slicing fitting data of the target gully head overhang includes:

[0079] Based on the rotating slicing fitting data of the target gully head overhang and the index extraction model, the overhang height, the overhang depth and the overhang area corresponding to each rotating slice are extracted.

[0080] In some examples, the index extraction model includes an overhang height extraction model, an overhang depth extraction model and an overhang area extraction model.

[0081] The extraction of the overhang height, the overhang depth and the overhang area corresponding to each rotating slice based on the rotating slicing fitting data of the target gully head overhang and the index extraction model includes:

[0082] Based on the rotating slicing fitting data of the target gully head overhang and the overhang height extraction model, the overhang height corresponding to each rotating slice is extracted.

[0083] extracting the overhang depth corresponding to each rotation slice based on the rotation slice fitting data of the target overhang and an overhang depth extraction model;

[0084] extracting the overhang area corresponding to each rotation slice based on the rotation slice fitting data of the target overhang and an overhang area extraction model.

[0085] In the present exemplary embodiment,

[0086] Before the point cloud overhang morphology quantification, the coordinate system of the two-dimensional point cloud after the slice projection and fitting needs to be defined. The present application defines the horizontal direction consistent with the concave direction in the two-dimensional point cloud as the X axis, and the vertical upward direction as the Y axis. The morphology parameters in the present application are all obtained by relative operation, so the coordinate origin is not defined. For the first rotation slice fitting data projection and the fitted two-dimensional point cloud , the overhang depth is calculated by the overhang depth extraction model:

[0087] The overhang depth extraction model is: (2);

[0088] wherein, is the maximum X coordinate of all points in , and is the minimum X coordinate of all points in . The overhang depth can be understood as the horizontal extension length of the concave hole under the overhang;

[0089] The overhang height of is calculated by the overhang height extraction model:

[0090] The overhang height extraction model is: (3);

[0091] wherein, is the maximum Y coordinate of all points in , and is the Y coordinate of the point with the maximum X value in . The overhang height can be understood as the soil thickness of the overhang.

[0092] The overhang area of the overhang is defined as the area occupied by the overhang soil layer in the radial extension direction of the concave hole, and the area is calculated by the overhang area extraction model. The first point to the point with the maximum X value , a total of points are involved Operations, cumulative operations The areas of the trapezoids are summed, and the specific model for extracting the area of ​​the suspended body is as follows:

[0093] (4);

[0094] in, , The first Point, number The x-coordinate of the point , The first Point, number The Y-coordinate of a point. For example... Figure 4 As shown, L Ci and H Ci The area enclosed by the fitted curve is the area of ​​the suspended body. L Ci and H Ci The direction of the area enclosed by the fitted curve is the radial outward extension direction of the concave cavity. Figure 6 This is a schematic diagram illustrating the evaluation indicators for suspended bodies provided in an embodiment of the present invention. Figure 6 The diagram shows the distribution of the evaluation indicators: suspended body depth, suspended body height, and suspended body area.

[0095] In some instances, the quantitative assessment of the stability of the target gully head suspension based on the evaluation metrics of the target gully head suspension includes:

[0096] Based on the evaluation index of the target trench head suspension body and the distance from the original point cloud to the rotation axis in each rotating slice, a quantitative evaluation model for the stability of the suspension body is established.

[0097] Based on the evaluation indicators and quantitative evaluation model of the target gully head suspension, the stability of the target gully head suspension is quantitatively evaluated.

[0098] In this exemplary embodiment, for the purpose of describing trench head stability, this application is based on , , The parameters propose a gully head stability index. The longitudinal profile of the gully head... The numerical value is positively correlated with the volume of the suspended body. This indicates the thickness of the soil mass in the suspended structure. In this case... The larger the diameter, the greater the cohesion and shear strength provided by the soil throughout the suspended body, the lower the probability of instability, and the more stable the suspended body. Therefore, it can be considered that... Inversely proportional to the stability of a suspended body, and It is directly proportional to the stability of the suspended body. Indicates having the same and The degree of concavity of the trench wall, The smaller the value, the greater the inward concavity of the trench wall (i.e., the less stable the suspended body). Therefore, formula (5) yields the following result. stability index :

[0099] (5);

[0100] in, It is a dimensionless parameter.

[0101] In this application, all two-dimensional point clouds are obtained. Feature parameters , , After obtaining the DHS index, the overall suspended depth of the trench head overhang needs to be calculated. ), Overall suspension height ( ), overall suspended area ( ), and the overall stability index ( This application uses a weighted average method to obtain the above parameters, which requires first processing each two-dimensional point cloud. The weights at the gully head are used for calculation. Considering the consistent step size (2°) during the rotation slicing process, the area represented by the point cloud intercepted further from the rotation center to the gully wall is larger. Therefore, this is used as the basis for calculating each two-dimensional point cloud. Weight in the trench head This process first calculates each... The average distance of all points from the rotation axis in the original point cloud. Subsequently based on The characteristic parameters of the trench head morphology are obtained from formulas (6) to (16):

[0102] The quantitative evaluation model for the stability of suspended bodies is as follows:

[0103] (6)

[0104] (5)

[0105] (7)

[0106] (8)

[0107] (9)

[0108] (10)

[0109] (11);

[0110] wherein, is the number of the rotational slice in the gully head; is the total number of the rotational slices in the gully head; is a two-dimensional point cloud representing the average arc length of the gully wall region; is the angle step (2°) in the rotational slicing process; is the value of the circular constant, taking 3.14; is a two-dimensional point cloud , wherein all points in the two-dimensional point cloud are projected onto the rotational axis to obtain the distance mean of all points in the two-dimensional point cloud to the rotational axis; is the weight of the two-dimensional point cloud , wherein, is used to evaluate the final overall stability of the overhanging body. , , is used to describe the final form of the overhanging body. In this application, the final overall stability of the overhanging body can be associated with the pressure that the overhanging body can bear. The value corresponds to the pressure that the overhanging body can bear. The greater the value , the greater the pressure that the overhanging body can bear.

[0111] In some examples, the three-dimensional scanning point cloud data of the target gully head overhanging body is segmented by the rotational slicing method to obtain the rotational slice plane data of the target gully head overhanging body, including:

[0112] The point cloud of the overhanging body is subjected to rotational slicing with the three-dimensional coordinate system origin as the axis and the z-axis as the rotation axis to obtain the rotational slice plane data of the target gully head overhanging body; wherein each rotational slice has a predetermined angle.

[0113] In the present exemplary embodiment, Figure 4 is a point cloud rotational slicing schematic diagram provided by the embodiment of the present application. As Figure 4 shown, the point cloud is subjected to slicing differentiation with 2° as the step from the slicing starting plane , i.e. , the points falling between the acute angle between the slicing plane and the slicing plane are divided into slicing point cloud to obtain the rotational slice plane data. Subsequently, the rotational slice plane data is vertically projected onto the slicing plane to obtain the plane point cloud , the X-axis of the plane point cloud points horizontally from the outside of the soil body to the inside of the soil body, and the Y-axis is perpendicular to the X-axis and points to the zenith direction.

[0114] In some instances, the step of performing data shrinking fitting on the rotational slice planar data of the target gully head overhang to obtain the rotational slice fitted data of the target gully head overhang includes:

[0115] The rotational slice plane data of the target trench head suspension body is compressed to the plane where the median angle value of the predetermined angle is located to obtain compressed plane data;

[0116] Line fitting is performed on the compressed plane data to obtain the rotational slice fitting data of the target trench head suspension.

[0117] In this exemplary embodiment, the 3D point cloud is affected by the accuracy of the point positions and is not presented in a planar form; that is, the point cloud has a certain thickness. Therefore, the strip-like features of the sliced ​​and projected planar point cloud are more prominent than the linear features, which does not match the actual linear features of the suspended body cross-section. This application can use the Laplace operator to shrink the planar point cloud, enhance the linear features of the planar point cloud, and accurately represent the cross-sectional shape of the suspended body.

[0118] The process of shrinking a planar point cloud based on the Laplace operator is as follows:

[0119] ①Use Algorithm (K-Nearest Neighbors) for determining planar point clouds of Neighborhood, denoted as ( ), Number of midpoints It is directly proportional to the number of points in the planar point cloud (the proportionality coefficient is 0.012).

[0120] ② Perform Deloni triangulation and extract all contained points. A point is a triangular facet, and a closed polygon formed by combining triangular faces is a point. A single-ring neighborhood, the vertex and point of the single-ring neighborhood Forming a single-ring neighborhood point set ( Figure 5 (As shown). Then, the Laplace matrix of the single-ring neighborhood points based on the cotangent weight is constructed using formula (12):

[0121] (12);

[0122] in, It is the cotangent weight Laplace matrix; It is the cotangent weight; , For indexes of single-ring neighborhood points; It represents the number of points in a single-ring neighborhood. It is the set of lines (edges) connecting the points in a single ring neighborhood; , These are indexes of points. and points The two opposite corners of the line (side).

[0123] After constructing the cotangent weight Laplacian matrix, the new vertices of the point cloud triangulation after shrinkage are solved using formula (13):

[0124] (13);

[0125] in, It is the cotangent weight Laplace matrix; These are the single-ring neighborhood points before contraction; These are the points in the single-ring neighborhood after the contraction. A diagonal matrix for controlling the contraction force; A diagonal matrix to maintain the original shape and strength.

[0126] A single planar point cloud shrinkage operation usually cannot achieve the desired effect, so iteration is required. and To achieve multiple contractions of the planar point cloud, device parameters are obtained based on existing point cloud data, and the recommended number of iterations is 6-10. For the [missing information]... Points in the next iteration Single-ring neighborhood point set The calculation of new vertices in the triangulation of the shrunk point cloud and The results are obtained by formulas (14) and (15) respectively:

[0127] (14)

[0128] (15);

[0129] in, For the first The diagonal matrix that controls the contraction intensity in each iteration; This is a diagonal matrix that maintains the original shape and strength during the first iteration; and They are respectively the first iteration and the second iteration. Before the next iteration The area of ​​the single-ring neighborhood; These are the iteration parameters. During the iterative shrinkage of the planar point cloud described above, The threshold is 3; The threshold is the identity matrix; The threshold is a diagonal matrix, and the diagonal values ​​are... S is the average area of ​​the single-ring neighborhood of all points in the initial planar point cloud. Figure 5 This is a schematic diagram of point cloud rotation and slicing data shrinkage provided in an embodiment of the present invention. Figure 5 As shown, the outer point cloud is shrunk to point cloud positions 2, 3, 4, 5, 6, and 7. Then, curve fitting is performed.

[0130] Since the planar point cloud obtained after iterative shrinkage is strip-shaped, but the number of points is clustered and disordered, which is not conducive to feature value extraction, cubic B-spline fitting is required for the shrunken planar point cloud. Point cloud sorting is a necessary condition for the implementation of the planar point cloud fitting algorithm. In this application, a greedy algorithm can be used to sort the planar point cloud. The highest point of the slice is defined as the starting point of the greedy algorithm, and the lower end point of the slice is defined as the ending point of the algorithm. The greedy algorithm constructs an ordered path by continuously selecting the nearest point to the current point, thereby sorting the planar point cloud. After sorting, the planar point cloud is fitted by cubic B-spline method using formula (16):

[0131] (16);

[0132] in, ; ; , , , These are four consecutive points. Thus, the shrinking point cloud rotated slice data can be fitted using the cubic B-spline method.

[0133] Figure 7 This is a schematic diagram illustrating the distribution of test verification sessions provided in an embodiment of the present invention. Figure 7 As shown, to verify the reliability of the practical significance of the morphological parameters of the gully head suspended bodies extracted in this application, a field water discharge and scouring experiment can be used to simulate the complex morphology of three gully heads, and then the parameters of each gully head can be extracted. The temporal distribution results of index and gravity erosion are presented. The data indicate that gravity erosion consistently occurs at the head of each runoff plot. When the index is relatively low, all landslides except for the gravity erosion in phases C6 and C7 of sub-area C occurred at the gully head. When the index is less than a certain fixed value, this value is 0.21, 0.17, and 0.28 in cell A, cell B, and cell C, respectively. This application considers this value to describe the stability of the ditch head cantilever. The safety line value of the index, i.e., the ditch head. When the index is greater than this value, the gully head overhang can be considered relatively stable and less prone to gravity erosion. The above results indicate that the proposed solution... The safety line of the index can be used to predict partial gravity erosion, wherein the safety line can be obtained by continuously monitoring the gravity erosion of a certain area and the corresponding index. Although inaccurate prediction results may occur in some cases due to the group occurrence characteristics of gravity erosion (such as C6 and C7), this may be the best solution under the current unclear mechanism of gravity erosion.

[0134] Figure 6 The head stability index (HDI) is the ratio of the safety line to the maximum gravity erosion of the field. The head stability index (HDI) is the ratio of the safety line to the maximum gravity erosion of the field. The index range.

[0135] The embodiment of the present application provides a device for quantifying the form of a head overhang based on a three-dimensional laser scanning point cloud. Figure 8 The device for quantifying the form of a head overhang based on a three-dimensional laser scanning point cloud provided by the embodiment of the present application is shown in the structure schematic diagram. Figure 8 As shown in the figure, it comprises:

[0136] The data acquisition unit 80 is used for acquiring three-dimensional scanning point cloud data of the target head by performing omnidirectional three-dimensional scanning on the target head based on a three-dimensional laser scanning system, and extracting three-dimensional scanning point cloud data of the head overhang of the target head in the three-dimensional scanning point cloud data of the target head.

[0137] The data segmentation unit 81 is used for performing data segmentation on the three-dimensional scanning point cloud data of the head overhang of the target head by means of rotating slicing, so as to obtain rotating slicing plane data of the head overhang of the target head.

[0138] The data fitting unit 82 is used for performing data contraction fitting on the rotating slicing plane data of the head overhang of the target head, so as to obtain rotating slicing fitting data of the head overhang of the target head.

[0139] The index extraction unit 83 is used for extracting evaluation indexes of the head overhang of the target head based on the rotating slicing fitting data of the head overhang of the target head.

[0140] The quantitative evaluation unit 84 is used for quantitatively evaluating the stability of the head overhang of the target head based on the evaluation indexes of the head overhang of the target head.

[0141] In the present exemplary embodiment, the target trench head is scanned in all directions by a three-dimensional laser scanning system to obtain three-dimensional scanning point cloud data of the target trench head, and three-dimensional scanning point cloud data of the overhanging body of the target trench head is extracted from the three-dimensional scanning point cloud data of the target trench head; the three-dimensional scanning point cloud data of the overhanging body of the target trench head is segmented by rotating slicing to obtain rotating slice plane data of the overhanging body of the target trench head; the rotating slice plane data of the overhanging body of the target trench head is contracted and fitted to obtain rotating slice fitting data of the overhanging body of the target trench head; evaluation indexes of the overhanging body of the target trench head are extracted based on the rotating slice fitting data of the overhanging body of the target trench head; and the stability of the overhanging body of the target trench head is quantitatively evaluated based on the evaluation indexes of the overhanging body of the target trench head. In the present application, the point cloud data of the trench head is obtained in all directions, the point cloud data is rotated and sliced, the evaluation indexes corresponding to each slice are extracted, and then the stability of the overhanging body of the target trench head is quantitatively evaluated based on the evaluation indexes corresponding to each slice, which is beneficial to more detailed index features and more accurate stability evaluation results.

[0142] Since the system / device described in the above-mentioned embodiments of the present application is used for the method of the above-mentioned embodiments of the present application, the specific structure and modification of the system / device can be understood by those skilled in the art based on the method described in the above-mentioned embodiments of the present application, and thus will not be described here. Any system / device used in the method of the above-mentioned embodiments of the present application belongs to the scope of the present application.

[0143] The embodiment of the present application provides a computer readable storage medium, which stores a three-dimensional laser scanning point cloud based trench head overhanging body form quantitative program. When the three-dimensional laser scanning point cloud based trench head overhanging body form quantitative program is executed by a processor, the three-dimensional laser scanning point cloud based trench head overhanging body form quantitative method described in each of the above-mentioned embodiments is realized.

[0144] The embodiment of the present application provides an electronic device, which includes a memory, a processor, and a three-dimensional laser scanning point cloud based trench head overhanging body form quantitative program stored in the memory and executable on the processor. When the three-dimensional laser scanning point cloud based trench head overhanging body form quantitative program is executed by the processor, the three-dimensional laser scanning point cloud based trench head overhanging body form quantitative method described in each of the above-mentioned embodiments is realized.

[0145] In the description of the present application, it should be understood that the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0146] In the present application, unless specifically defined otherwise, the terms "mounting", "connected", "connecting", "fixed", "fixedly connected" and the like should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrated; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected via an intermediate medium; can be internal communication of two elements, or interaction between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0147] In the present application, unless specifically defined otherwise, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature is "above", "over" and "on" the second feature, which can be directly above or obliquely above the second feature, or only indicates that the first feature is higher than the second feature in horizontal height. The first feature is "below", "under" and "under" the second feature, which can be directly below or obliquely below the second feature, or only indicates that the first feature is lower than the second feature in horizontal height.

[0148] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples, without contradiction.

[0149] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can modify, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for quantifying the shape of a head-ditch overhang based on a three-dimensional laser scanning point cloud, characterized in that, The method comprises the following steps: comprehensive three-dimensional scanning of a target ridge head by a three-dimensional laser scanning system to obtain three-dimensional scanning point cloud data of the target ridge head, and extracting three-dimensional scanning point cloud data of a suspended body of the target ridge head from the three-dimensional scanning point cloud data of the target ridge head; data segmentation of the three-dimensional scanning point cloud data of the suspended body of the target ridge head by means of rotational slicing to obtain rotational slice plane data of the suspended body of the target ridge head; data shrinkage fitting of the rotational slice plane data of the suspended body of the target ridge head to obtain rotational slice fitting data of the suspended body of the target ridge head; evaluation index extraction of the suspended body of the target ridge head based on the rotational slice fitting data of the suspended body of the target ridge head; quantitative evaluation of the stability of the suspended body of the target ridge head based on the evaluation index of the suspended body of the target ridge head; wherein the evaluation index comprises a suspended body height, a suspended body depth and a suspended body area corresponding to each rotational slice. The evaluation index extraction of the suspended body of the target ridge head based on the rotational slice fitting data of the suspended body of the target ridge head comprises: extracting the suspended body height, the suspended body depth and the suspended body area corresponding to each rotational slice based on the rotational slice fitting data of the suspended body of the target ridge head and an index extraction model; wherein the index extraction model comprises a suspended body height extraction model, a suspended body depth extraction model and a suspended body area extraction model. The extraction of the suspended body height, the suspended body depth and the suspended body area corresponding to each rotational slice based on the rotational slice fitting data of the suspended body of the target ridge head and the index extraction model comprises: extracting the suspended body height corresponding to each rotational slice based on the rotational slice fitting data of the suspended body of the target ridge head and the suspended body height extraction model; extracting the suspended body depth corresponding to each rotational slice based on the rotational slice fitting data of the suspended body of the target ridge head and the suspended body depth extraction model; extracting the suspended body area corresponding to each rotational slice based on the rotational slice fitting data of the suspended body of the target ridge head and the suspended body area extraction model.

2. The method for quantifying the shape of a hanging head according to claim 1, wherein, The quantitative evaluation of the stability of the suspended body of the target ridge head based on the evaluation index of the suspended body of the target ridge head comprises: establishing a suspended body stability quantitative evaluation model based on the evaluation index of the suspended body of the target ridge head and the distance from the original point cloud to the rotation axis in each rotational slice; quantitative evaluation of the stability of the suspended body of the target ridge head based on the evaluation index of the suspended body of the target ridge head and the suspended body stability quantitative evaluation model. 3.The method of quantifying the shape of a hanging head according to the three-dimensional laser scanning point cloud of claim 1, wherein, The data segmentation of the three-dimensional scanning point cloud data of the suspended body of the target ridge head by means of rotational slicing to obtain the rotational slice plane data of the suspended body of the target ridge head comprises: rotational slicing of the suspended body point cloud with the three-dimensional coordinate system origin as the axis and the z-axis as the rotation axis to obtain the rotational slice plane data of the suspended body of the target ridge head; wherein each rotational slice has a predetermined angle.

4. The method for quantifying the shape of a hanging head according to claim 3, wherein, The data shrinkage fitting of the rotational slice plane data of the suspended body of the target ridge head to obtain the rotational slice fitting data of the suspended body of the target ridge head comprises: The rotation slice plane data of the target gully head overhang is compressed to a plane where an intermediate angle value of the predetermined angle is located, to obtain compressed plane data; Line fitting is performed on the compressed plane data to obtain rotation slice fitting data of the target gully head overhang.

5. The method for quantifying the shape of a overhang at a gully head based on a three-dimensional laser scanning point cloud according to claim 1, wherein, The three-dimensional laser scanning system is used to perform all-around three-dimensional scanning on the target gully head to obtain three-dimensional scanning point cloud data of the target gully head, including: N spherical targets are arranged in a scanning area; The area where the N spherical targets are located is scanned multiple times from different angles to obtain multiple topographic point clouds at different angles; each topographic point cloud covers at least one spherical target; Point cloud splicing is performed based on the center coordinates of the spherical targets in each topographic point cloud to obtain three-dimensional scanning point cloud data of the target gully head.

6. A device for quantifying the shape of a headcut overhang based on a three-dimensional laser scanning point cloud, characterized in that, It includes: A data acquisition unit is configured to perform all-around three-dimensional scanning on the target gully head based on a three-dimensional laser scanning system, to obtain three-dimensional scanning point cloud data of the target gully head, and to extract three-dimensional scanning point cloud data of a target gully head overhang from the three-dimensional scanning point cloud data of the target gully head; A data segmentation unit is configured to perform data segmentation on the three-dimensional scanning point cloud data of the target gully head overhang by means of rotation slicing to obtain rotation slice plane data of the target gully head overhang; A data fitting unit is configured to perform data contraction fitting on the rotation slice plane data of the target gully head overhang to obtain rotation slice fitting data of the target gully head overhang; An index extraction unit is configured to extract evaluation indexes of the target gully head overhang based on the rotation slice fitting data of the target gully head overhang; A quantitative evaluation unit is configured to quantitatively evaluate the stability of the target gully head overhang based on evaluation indexes of the target gully head overhang; the evaluation indexes include the overhang height, overhang depth and overhang area corresponding to each rotation slice; The evaluation index extraction of the target gully head overhang based on the rotation slice fitting data of the target gully head overhang includes: The overhang height, overhang depth and overhang area corresponding to each rotation slice are extracted based on the rotation slice fitting data of the target gully head overhang and an index extraction model; the index extraction model includes an overhang height extraction model, an overhang depth extraction model and an overhang area extraction model; The overhang height, overhang depth and overhang area corresponding to each rotation slice are extracted based on the rotation slice fitting data of the target gully head overhang and an index extraction model, including: The overhang height corresponding to each rotation slice is extracted based on the rotation slice fitting data of the target gully head overhang and the overhang height extraction model; The overhang depth corresponding to each rotation slice is extracted based on the rotation slice fitting data of the target gully head overhang and the overhang depth extraction model; The overhang area corresponding to each rotation slice is extracted based on the rotation slice fitting data of the target gully head overhang and the overhang area extraction model.

7. A computer-readable storage medium, characterized in that, A computer readable storage medium having stored thereon a three-dimensional laser scanning point cloud based gully head overhang form quantification program, which, when executed by a processor, implements the three-dimensional laser scanning point cloud based gully head overhang form quantification method of any one of claims 1-5.

8. An electronic device, comprising: A computer readable storage medium having stored thereon a three-dimensional laser scanning point cloud based gully head overhang form quantification program, which, when executed by a processor, implements the three-dimensional laser scanning point cloud based gully head overhang form quantification method of any one of claims 1-5.

Images