A method of describing a network of underground pipelines having cracks

Abstract

This invention discloses a method for describing network cracks in underground pipelines, comprising the following steps: Step 1) Obtaining a three-dimensional point cloud of the crack surface using a depth camera, and extracting the three-dimensional coordinates of each point on the crack in the measurement coordinate system as sampling points; Step 2) Centrifuging the three-dimensional coordinates of the crack points; Step 3) Fitting a spatial plane using the centrifuged points; Step 4) Calculating the angle between the plane containing the crack point and the horizontal plane XOY, and projecting the crack point onto the horizontal plane XOY using Rodriguez rotation based on the angle; Step 5) Calculating the minimum bounding rectangle area of ​​the crack point on the horizontal plane XOY to describe the network cracks in underground pipelines. This method projects three-dimensional points on an arbitrary orientation spatial plane onto a two-dimensional plane, thereby solving for the minimum bounding rectangle area on the two-dimensional plane to describe the network cracks in underground pipelines.

Description

Technical Field

[0001] This invention belongs to the field of underground pipeline network crack measurement, and particularly relates to a method for describing underground pipeline network cracks. Background Technology

[0002] The network of cracks in underground pipelines consists of numerous intersecting cracks. It is generally described by the area of ​​its minimum bounding rectangle. To accurately calculate the area of ​​the minimum bounding rectangle, the spatial positions of its four vertices must first be determined. Because a depth camera cannot be perfectly perpendicular to the plane containing the cracks, the image it acquires is a plane in three-dimensional space.

[0003] Existing methods for calculating the minimum bounding rectangle are generally suitable for situations where the target is located on a horizontal or vertical plane. However, these methods fail when the angle between the plane containing the target and the horizontal plane is not 0° or 90°. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for describing network cracks in underground pipelines, thereby solving the aforementioned technical problems. Specifically, this method is implemented through the following technical solution:

[0005] The method for describing the network of cracks in the underground pipeline includes the following steps:

[0006] Step 1) Obtain the three-dimensional point cloud of the crack surface using a depth camera, and extract the three-dimensional coordinates of each sampling point on the crack in the measurement coordinate system;

[0007] Step 2) Centroidify the three-dimensional coordinates of the crack points;

[0008] Step 3) Fit the spatial plane using the centroid-normalized points;

[0009] Step 4) Calculate the angle θ between the plane where the crack point is located and the horizontal plane XOY, and project the crack point onto the horizontal plane XOY by Rodriguez rotation based on the angle θ.

[0010] Step 5) Calculate the minimum bounding rectangle area of ​​the crack points in the horizontal plane XOY to describe the network cracks of underground pipelines.

[0011] A further design of the method for describing the network of cracks in underground pipelines is that, in step 1), the three-dimensional coordinates of the sampling points are set as (X... i ,Y i Z i (i = 1, 2, ..., n), where n is the number of sampling points.

[0012] A further design of the method for describing the network of cracks in underground pipelines is that, in step 2), the centroid of all crack points is calculated according to equation (1). Then subtract the centroid value from the coordinates of each point to obtain the centroid-normalized crack point coordinates (x). i ,y i ,z i (i = 1, 2, ..., n).

[0013]

[0014]

[0015] A further design of the method for describing the network cracks in underground pipelines is that, in step 3), the equation of the spatial plane is set as ax + by + cz = 0, where (a, b, c) is the unit normal vector of the plane where the crack point is located, and the unit normal vector (a, b, c) of the plane is obtained by singular value decomposition.

[0016] A further design of the method for describing the network of cracks in underground pipelines is that, in step 4), the included angle θ is calculated according to equation (1).

[0017]

[0018] In equation (2), Let (a, b, c) be the unit normal vector of the plane containing the crack point. Let (0,0,1) be the unit normal vector of the horizontal plane XOY.

[0019] A further design of the method for describing the network of cracks in underground pipelines is that the projection process in step 4) is as follows: for all centroided crack points P i =(x i ,y i ,z i ) T After performing the Rodriguez rotation according to equation (2), the corresponding point on the horizontal plane XOY is P. i ′=(x i ′,y i ′,z i ′) T ,

[0020] P i ′=P i cos(θ)+(k×P i sin(θ) + k < k, P i >(1-cos(θ)) (3)

[0021] In equation (3), <> represents the dot product of vectors, and × represents the cross product of vectors.

[0022] A further design of the method for describing the network of cracks in underground pipelines is that, in step 5), discrete points P are calculated according to the corresponding algorithm. i Find the minimum bounding rectangle of the region (i = 1, 2, ..., n), and find the four vertices P of the rectangle. j ′=(x′ j ,y′ j ,z′ j ) T (j=a,b,c,d), and at the same time obtain the area of ​​the smallest bounding rectangle.

[0023] A further design of the method for describing the network cracks in underground pipelines is that, in step 5), according to equation (3), the vertices of the minimum circumscribed rectangle are restored to three-dimensional space by Rodriguez rotation, and the four vertices P of the rectangle are... j ′=(x′ j ,y′ j ,z′ j ) T (j = a, b, c, d) is rotated by Rodrigues to transform to the plane where the crack point was originally located in order to further describe the crack;

[0024] P j =P j cos(θ)+(l×P) j ′)sin(θ)+l<l,P j ′>(1-cos(θ))+ΔX (4)

[0025] In equation (4), P j =(x j ,y j ,z j ) T These are the four vertices of the smallest bounding rectangle on the plane where the crack point is located.

[0026] The present invention also provides an electronic device, including a memory, a processor, and a computer program, wherein the computer program is stored in the memory and configured to be executed by the processor to implement the method for describing the underground pipeline network cracks.

[0027] The present invention also provides a computer-readable storage medium storing a computer program that is executed by a processor to implement a method for describing the network of cracks in the underground pipeline.

[0028] The beneficial effects of this invention are:

[0029] The method for describing underground pipeline network cracks in this invention utilizes Rodriguez rotation to project three-dimensional points on an arbitrary orientation space plane onto a two-dimensional plane. This enables the calculation of the minimum bounding rectangle area on the two-dimensional plane to describe the underground pipeline network cracks. Furthermore, Rodriguez rotation is used again to restore the vertices obtained in the previous step to the plane in three-dimensional space to further describe the underground pipeline network cracks. This solves the problem that existing minimum bounding rectangle calculation methods are not applicable when the angle between the plane where the observation target is located and the horizontal plane is not 0° or 90°. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the 3D point cloud in step 1). Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0032] The method for describing underground pipeline network cracks in this embodiment includes the following steps:

[0033] Step 1) Obtain the three-dimensional point cloud of the crack surface using a depth camera, and extract the three-dimensional coordinates of each sampling point on the crack in the measurement coordinate system.

[0034] Step 2) Centroidify the three-dimensional coordinates of the crack points.

[0035] Step 3) Fit the spatial plane using the centroid-normalized points.

[0036] Step 4) Calculate the angle θ between the plane containing the crack point and the horizontal plane XOY, and project the crack point onto the horizontal plane XOY by Rodriguez rotation based on the angle θ.

[0037] Step 5) Calculate the minimum bounding rectangle area of ​​the crack points in the horizontal plane XOY to describe the network cracks of underground pipelines.

[0038] Furthermore, in step 1), the three-dimensional coordinates of the sampling point are set as (X... i ,Y i Z i (i = 1, 2, ..., n), where n is the number of sampling points.

[0039] Furthermore, in step 2), the centroids of all crack points are calculated according to equation (1). Then subtract the centroid value from the coordinates of each point to obtain the centroid-normalized crack point coordinates (x). i ,y i ,z i (i = 1, 2, ..., n).

[0040]

[0041] Furthermore, in step 3), the equation of the spatial plane is set as ax + by + cz = 0, where (a, b, c) is the unit normal vector of the plane where the crack point is located, and the unit normal vector (a, b, c) of the plane is obtained by singular value decomposition.

[0042] Furthermore, in step 4), the included angle θ is calculated according to equation (1).

[0043]

[0044] in, Let (a, b, c) be the unit normal vector of the plane containing the crack point. Let (0,0,1) be the unit normal vector of the horizontal plane XOY.

[0045] In step 4) of this embodiment, the projection process is as follows: For all centroid-centered crack points P... i =(x i ,y i ,z i ) T After performing the Rodriguez rotation according to equation (2), the corresponding point on the horizontal plane XOY is P. i ′=(x i ′,y i ′,z i ′) T ,

[0046] P i ′=P i cos(θ)+(k×P i sin(θ) + k < k, P i >(1-cos(θ)) (2)

[0047] In the formula <> represents the dot product of vectors, and × represents the cross product of vectors. Through this step, point P... i The Z-coordinate values ​​of all points are 0, i.e., z = 0. i ′=0.

[0048] In step 5), the discrete point P is calculated according to the corresponding algorithm. i Find the minimum bounding rectangle of the region (i = 1, 2, ..., n), and find the four vertices P of the rectangle. j ′=(x′ j ,y′ j ,z′ j ) T (j = a, b, c, d), and simultaneously obtain the area of ​​the minimum bounding rectangle. In this embodiment, the corresponding algorithm described above can be a principal axis finding method or a method combining vertex chain codes and discrete Green's algorithm.

[0049] Further step 5) According to equation (3), restore the vertices of the minimum bounding rectangle to three-dimensional space through Rodrigues rotation, and set the four vertices P of the rectangle to... j ′=(x′ j ,y′ j ,z′ j ) T Perform a Rodrigues rotation on (j = a, b, c, d) to transform it to the plane where the crack point was originally located, in order to further describe the crack's more detailed morphology.

[0050] P j =P j cos(θ)+(l×P) j ′)sin(θ)+l<l,P j ′>(1-cos(θ))+ΔX (3)

[0051] In equation (3), P j =(x j ,y j ,z j ) T These are the four vertices of the smallest bounding rectangle on the plane where the crack point is located.

[0052] This embodiment also provides an electronic device, including a memory, a processor, and a computer program, wherein the computer program is stored in the memory and configured to be executed by the processor to implement the method for describing the underground pipeline network cracks.

[0053] This embodiment also provides a computer-readable storage medium storing a computer program that is executed by a processor to implement the method for describing the network of cracks in the underground pipeline.

[0054] The method for describing underground pipeline network cracks in this embodiment utilizes Rodriguez rotation to project three-dimensional points on an arbitrary orientation space plane onto a two-dimensional plane. This enables the calculation of the minimum bounding rectangle area on the two-dimensional plane to describe the underground pipeline network cracks. Furthermore, Rodriguez rotation is used again to restore the vertices obtained in the previous step to the plane in three-dimensional space to further describe the underground pipeline network cracks. This solves the problem that existing minimum bounding rectangle calculation methods are not applicable when the angle between the plane where the observation target is located and the horizontal plane is not 0° or 90°.

[0055] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

Claims

1. A method for describing network cracks in underground pipelines, characterized in that... Includes the following steps: Step 1) Obtain the three-dimensional point cloud of the crack surface using a depth camera, and extract the three-dimensional coordinates of each sampling point on the crack in the measurement coordinate system; Step 2) Centroidify the three-dimensional coordinates of the crack points; Step 3) Fit the spatial plane using the centroid-normalized points; Step 4) Calculate the angle θ between the plane where the crack point is located and the horizontal plane XOY, and project the crack point onto the horizontal plane XOY by Rodriguez rotation based on the angle θ. Step 5) Calculate the minimum bounding rectangle area of ​​the crack points in the horizontal plane XOY to describe the network cracks of underground pipelines; In step 1), the three-dimensional coordinates of the sampling point are set as (X... i ,Y i Z i (i = 1, 2, ..., n), where n is the number of sampling points; In step 2), the centroid of all crack points is calculated according to equation (1). Then subtract the centroid value from the coordinates of each point to obtain the centroid-normalized crack point coordinates (x). i ,y i ,z i (i = 1, 2, ..., n); In step 3), the equation of the spatial plane is set as ax + by + cz = 0, where (a, b, c) is the unit normal vector of the plane where the crack point is located, and the unit normal vector (a, b, c) of the plane is obtained by singular value decomposition. In step 4), the included angle θ is calculated according to equation (2). in, Let (a, b, c) be the unit normal vector of the plane containing the crack point. Let (0,0,1) be the unit normal vector of the horizontal plane XOY. The projection process in step 4) is as follows: For all centroided crack points P i =(x i ,y i ,z i ) T After performing the Rodriguez rotation according to equation (3), the corresponding point on the horizontal plane XOY is P. i ′=(x′ i ,y′ i ,z′ i ) T , P i ′=P i cos(θ)+(k×P i )sin(θ)+k<k,P i >(1-cos(θ)) (3) In the formula <> represents the dot product of vectors, and × represents the cross product of vectors; Step 5) specifically involves calculating the discrete point P. i Find the minimum bounding rectangle of the rectangle (i = 1, 2, ..., n), and find the four vertices P' of the rectangle. j =(x′) j ,y′ j ,z′ j ) T (j=a,b,c,d), and at the same time obtain the area of ​​the smallest bounding rectangle; According to equation (3), the vertices of the minimum bounding rectangle are restored to three-dimensional space by Rodriguez rotation, and the four vertices P′ of the rectangle are... j =(x′) j ,y′ j ,z′ j ) T (j = a, b, c, d) is rotated by Rodrigues to transform to the plane where the crack point was originally located in order to further describe the crack; P j =P′ j cos(θ)+(l×P′ j )sin(θ)+l<l,P′ j >(1-cos(θ))+ΔX (4) In equation (4), P j =(x j ,y j ,z j ) T These are the four vertices of the smallest bounding rectangle on the plane where the crack point is located.

2. An electronic device, characterized in that, It includes a memory, a processor, and a computer program, wherein the computer program is stored in the memory and configured to be executed by the processor to implement the method for describing underground pipeline network cracks as described in claim 1.

3. A computer-readable storage medium, characterized in that... The storage medium stores a computer program that is executed by a processor to implement the method for describing underground pipeline network cracks as described in claim 1.

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