Stay cable length measuring method based on three-dimensional laser point cloud

Abstract

The invention discloses a stay cable length measurement method based on a three-dimensional laser point cloud, and the method obtains a three-dimensional point cloud model of a stay cable through high-precision laser scanning, and achieves the automatic recognition and precise calculation of the length of the stay cable. The method comprises the following steps: firstly, scanning a stay cable surface of a to-be-measured cable-stayed bridge by using a three-dimensional laser scanner to obtain a point cloud model of a single stay cable; then, segmenting the point cloud model of the stay cable into a plurality of point cloud segments; thirdly, coordinate transformation is carried out on the point cloud cut sections, center coordinates of the point cloud cut sections are calculated, and the cable length of the three-dimensional laser point cloud part is obtained according to the center coordinates of all the point cloud cut sections; and finally, obtaining the anchoring length of the stay cable in the beam body and the tower body according to the design data, and calculating to obtain the cable length of the stay cable, thereby realizing the rapid and efficient measurement of the cable length of the stay cable.

Description

Technical Field

[0001] The invention relates to the field of bridge engineering measurement, and in particular to a method for measuring the length of a stay cable based on three-dimensional laser point clouds. Background Art

[0002] With the rapid development of transportation construction projects, a large number of large-span cable-stayed bridges have been built in my country. Cable-stayed bridges have several symmetrically distributed cables, which are a structural form with relatively complex stress conditions in bridge structures. Cables are responsible for transmitting loads between the towers and the main beams, and are important load-bearing components of cable-stayed bridges. Before replacing the cables of a cable-stayed bridge, it is necessary to determine the length of the cables. However, since the cables of a cable-stayed bridge are curved in normal working conditions, and due to the relaxation of the internal steel wires, changes in cable force, etc., the actual length of the cables that have been working for a long time is different from the length in the design data, which is difficult to meet the actual situation.

[0003] At present, the traditional method of measuring the length of the cable-stayed cable mainly relies on manual measurement and on-site construction data, which is not only time-consuming and labor-intensive, but also has large measurement errors. With the development of laser scanning technology, the acquisition of high-precision three-dimensional point cloud data has become more convenient and efficient. The measurement method based on the point cloud model can provide detailed structural geometry information and high-precision measurement results without contacting the structure, and has gradually become an important tool for structural health monitoring and detection of bridge engineering. Therefore, how to use three-dimensional laser scanning technology to determine the length of the cable-stayed cable, reduce the measurement error of the cable-stayed cable length, and make the measured value of the cable-stayed cable length consistent with the actual situation is of great significance. Summary of the invention

[0004] The problem to be solved by the present invention is: in view of the shortcomings of the traditional method for measuring the length of the inclined cable, the present invention provides a method for measuring the length of the inclined cable based on three-dimensional laser point cloud, which can quickly and efficiently complete the measurement of the length of the inclined cable.

[0005] The present invention adopts the following technical solution: a method for measuring the length of a stay cable based on a three-dimensional laser point cloud, comprising the following steps:

[0006] Step 1: Use a 3D laser scanner to scan the cable surface of the cable-stayed bridge to obtain a point cloud model {x, y, z} of a single cable;

[0007] Step 2: Segment the point cloud model {x, y, z} of a single cable to obtain multiple point cloud segments {x i ,y i ,z i};

[0008] Step 3: Segment the point cloud {x i ,y i ,z i} to transform the coordinates and obtain the cross-sectional point cloud {y w ,z w};

[0009] Step 4: For the cross-section point cloud {y w ,z w} Fit the coordinates of the center of the cross section and calculate the point cloud segment {x i ,y i ,z i}'s center coordinates;

[0010] Step 5: Use the center coordinates of all point cloud segments to calculate the cable length L0 of the 3D laser point cloud part, and combine the anchorage lengths L1 and L2 of the cable inside the beam and tower body in the design data to obtain the cable length L of the cable.

[0011] Preferably, step 1 specifically includes the following steps:

[0012] Step 1.1: Determine the location of the ground 3D laser scanner station according to the size and accuracy requirements of the cable to be measured on the cable-stayed bridge.

[0013] Step 1.2: Use a 3D laser scanner to scan the cable surface of the cable-stayed bridge to collect point cloud data of the cable surface. The cable scanning range is the cable between the intersection of the cable and the main beam and the intersection with the main tower;

[0014] Step 1.3: After scanning the cable surface to be measured and obtaining the cable surface point cloud data, preprocessing the cable surface point cloud data is performed;

[0015] The cable surface point cloud data is converted into a direction in which the x-axis corresponds to the length of the cable, the y-axis corresponds to the horizontal direction perpendicular to the length of the cable, and the z-axis corresponds to the height of the cable. Subsequently, the point cloud model {x, y, z} of a single cable is extracted from the cable surface point cloud data.

[0016] Preferably, in step 2, the cable point cloud data is divided into a plurality of straight line point cloud segments, and a point cloud segment {x} is cut out along the x-axis direction at a horizontal length of every ΔL in the cable point cloud data {x, y, z}. i ,y i ,z i},as follows:

[0017]

[0018] Where m is the number of point cloud segments, rounded up, i = 1, 2, ..., m; ΔL is in the range of 0.1 m to 1 m, ensuring that there are enough points when fitting the circular curve of the cross section of the point cloud segment to reduce the random error of fitting; x max is the maximum value of x in the point cloud model {x, y, z}, x minIt is the minimum value of x in the point cloud model {x, y, z}.

[0019] Preferably, step 3 specifically includes the following steps:

[0020] Step 3.1: Use a cubic polynomial to fit the point cloud model of the entire cable to obtain an approximate linear curve of the cable. The polynomial equation is as follows:

[0021] z=Ax 3 +Bx 2 +Cx+D

[0022] Where A, B, C, and D are polynomial coefficients, and x and z are x and z in {x, y, z}.

[0023] Step 3.2: Calculate the linear tangent angle α0 of the point cloud segment according to the polynomial equation as follows:

[0024] α0=arctan(3Ax A 2 +2Bx A +C)

[0025] Among them, x A Segment the point cloud {x i ,y i ,z i}The x-axis coordinate value of the point (point A) corresponding to the minimum z-axis value in .

[0026] Step 3.3: Point cloud segmentation {x i ,y i ,z i}Rotate α0 with point A as the reference point in the xz-axis plane to obtain the rotated point cloud fragment {x w ,y w ,z w}, and then project the rotated point cloud fragment onto the yz-axis plane to obtain the cross-sectional point cloud {y w ,z w}, the calculation is as follows:

[0027] y w =y i

[0028] z w =(x i -x A )sinα0+(z i -z A )cosα0+z A

[0029] Preferably, step 4 specifically includes the following steps:

[0030] Step 4.1: According to the cross-section point cloud {y w ,z w}, the least square method is used to fit the center of the cross section, and the fitting circle equation is:

[0031]

[0032] Where n is the number of points in the cross-sectional point cloud, and a, b, c, d, and e are all fitting coefficients.

[0033] Step 4.2: According to the radius r of the fitted circle and the coordinates of the center of the fitted circle (y r ,z r ), calculate the segment of the rotated point cloud {x w ,y w ,z w The coordinates of the centroid (x0, y0, z0) are calculated as follows:

[0034]

[0035] y0=y r

[0036] z0=z r

[0037] Where α0 is the linear tangent angle of the point cloud segment, x A is the x-axis coordinate value of point A.

[0038] Step 4.3: Rotate the centroid coordinates (x0, y0, y0) in the xz-axis plane back to the initial point cloud fragment {x i ,y i ,z i}, and obtain the center coordinates (x c ,y c ,z c );

[0039] The rotation takes point A as the reference point, and the rotation angle is -α0. The formula is as follows:

[0040] x c =(x0-x A )cos(-α)-(z0-z A )sin(-α)+x A

[0041] y c =y0

[0042] z c =(x0-x A )sin(-α)+(z0-z A )cos(-α)+z A

[0043] Preferably, step 5 specifically includes the following steps:

[0044] Step 5.1: Calculate the center coordinates (x c ,y c ,z c ), the center coordinates of all point cloud segments (x c ,y c ,z c ) form the precise linear coordinate points of the inclined cable {x ci ,y ci ,z ci}, the formula is as follows:

[0045]

[0046] Where m is the number of point cloud segments.

[0047] Step 5.2: According to the linear coordinate point {x ci ,y ci ,z ci}Calculate the cable length L0 of the three-dimensional laser point cloud part. The specific calculation formula is as follows:

[0048]

[0049] Step 5.3: Obtain the anchorage lengths L1 and L2 of the cable in the beam and tower body according to the design data, and calculate the cable length L of the cable as follows:

[0050] L=L0+L1+L2.

[0051] The technical solution of the present invention also provides: an electronic device, comprising:

[0052] one or more processors;

[0053] a storage device having one or more programs stored thereon;

[0054] When the one or more programs are executed by the one or more processors, the one or more processors implement any of the above-mentioned methods for measuring the length of a stayed cable based on three-dimensional laser point clouds.

[0055] The technical solution of the present invention also provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps in any of the above-mentioned methods for measuring the length of a cable based on a three-dimensional laser point cloud are implemented.

[0056] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0057] The cable length measurement method of the present invention applies the three-dimensional laser scanning technology to the cable length measurement of the cable, and utilizes the characteristics of the three-dimensional laser scanning technology such as non-contact measurement, high measurement accuracy and high measurement efficiency to realize the accurate calculation of the cable length of the cable. The point cloud model of the cable is divided into multiple point cloud segments, the center coordinates of the point cloud segments are calculated, and the cable length of the three-dimensional laser point cloud part is obtained according to the center coordinates of all the point cloud segments. Then, the anchorage length of the cable in the beam body and the tower body is obtained according to the design data, and the cable length of the cable is calculated, thereby realizing the rapid and efficient measurement of the cable length of the cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a flow chart of the steps of the method for measuring the length of a stay cable based on three-dimensional laser point cloud of the present invention;

[0059] Figure 2 It is a schematic diagram of a point cloud model of a single inclined cable of the present invention;

[0060] Figure 3 Schematic diagram of calculating the linear angle α0 of the point cloud segment according to the present invention;

[0061] Figure 4 A flow chart of the steps for calculating the cross-sectional point cloud of the present invention;

[0062] Figure 5 This is a schematic diagram of calculating the center coordinates of the point cloud segment in the present invention. DETAILED DESCRIPTION

[0063] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the application is further elaborated in detail below in conjunction with the accompanying drawings. The described embodiments are only a part of the embodiments involved in the present invention. All non-innovative embodiments of other researchers in the field on this embodiment belong to the protection scope of the present invention. At the same time, for the step numbering in the embodiment of the present invention, it is only set for the convenience of explanation, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0064] In one embodiment of the present invention, a method for measuring the length of a stay cable based on a three-dimensional laser point cloud is provided. Figure 1 As shown, the following steps are included:

[0065] Step 1: Use a 3D laser scanner to scan the cable surface of the cable-stayed bridge to obtain a point cloud model {x, y, z} of a single cable.

[0066] This embodiment applies 3D laser scanning technology to the measurement of the length of the stay cable. The specific method is as follows: Figure 2 As shown, the sub-steps are as follows:

[0067] Step 1.1: Determine the location of the ground 3D laser scanner station according to the size and accuracy requirements of the cable surface where the cable to be measured on the cable-stayed bridge is located;

[0068] Step 1.2: Use a 3D laser scanner to scan the cable surface of the cable to be measured, and collect point cloud data of the cable surface of the cable to be measured. The scanning range of the cable is the cable between the intersection of the cable with the main beam and the intersection with the main tower;

[0069] Step 1.3: After scanning the cable surface to be measured and obtaining the cable surface point cloud data, the cable surface point cloud data is preprocessed. The cable surface point cloud data is converted into a direction in which the x-axis corresponds to the length of the inclined cable, the y-axis corresponds to the horizontal direction perpendicular to the length of the inclined cable, and the z-axis corresponds to the height of the inclined cable; then, the point cloud model {x, y, z} of a single inclined cable is extracted from the cable surface point cloud data.

[0070] Step 2: Segmentation of the cable point cloud data.

[0071] Since the linear shape of the inclined cable is a curve, in order to facilitate calculation, the linear shape of the inclined cable can be fitted using multiple straight lines. Therefore, in this embodiment, the point cloud data of the inclined cable is divided into multiple straight line point cloud segments.

[0072] Specifically, the point cloud model {x, y, z} of a single cable is segmented, and a point cloud segment {x} is cut out every 1 meter along the x-axis direction in the point cloud model {x, y, z} of the cable. i ,y i ,z i}, the calculation is as follows:

[0073]

[0074] Where m is the number of point cloud segments, rounded up, i = 1, 2, ..., m; x max is the maximum value of x in the point cloud model {x, y, z}, x min It is the minimum value of x in the point cloud model {x, y, z}.

[0075] Step 3: Point cloud segment coordinate conversion, point cloud segment {x i ,y i ,z i} to transform the coordinates and obtain the cross-sectional point cloud {y w ,z w}, the specific sub-steps are as follows:

[0076] Step 3.1: Accurately calculating the linear tangent of each point cloud segment is crucial to obtaining a reliable cross-sectional point cloud. In this embodiment, a cubic polynomial is used to fit the point cloud model of the entire cable segment to obtain an approximate linear curve of the cable. The polynomial equation is as follows:

[0077] z=Ax 3 +Bx 2 +Cx+D

[0078] Among them, A, B, C, D are polynomial coefficients, and x and z are x and z in the point cloud model {x, y, z}.

[0079] Step 3.2: Calculate the linear tangent angle α0 of the point cloud segment according to the polynomial equation, such as Figure 3 As shown, the calculation is as follows:

[0080] α0=arctan(3Ax A 2 +2Bx A +C)

[0081] Among them, x A Segment the point cloud {x i ,y i ,z i}The x-axis coordinate value of the point (point A) corresponding to the minimum z-axis value in .

[0082] Step 3.3: Cross-section point cloud {y w ,z w}calculate;

[0083] like Figure 4 As shown, the point cloud segment {x i ,y i ,z i}Rotate α0 with point A as the reference point in the xz-axis plane to obtain the rotated point cloud fragment {x w ,y w ,z w}.

[0084] Then, the rotated point cloud fragment is projected onto the yz-axis plane to obtain the cross-sectional point cloud {y w ,z w}, the calculation is as follows:

[0085] y w =y i

[0086] z w =(x i -x A )sinα0+(z i -z A )cosα0+z A

[0087] Step 4: For the cross-section point cloud {y w ,z w} Fit the coordinates of the center of the cross section and calculate the point cloud segment {xi ,y i ,z i}, such as Figure 5 As shown, the specific steps include:

[0088] Step 4.1: Fitting the center of the cross-section point cloud.

[0089] According to the cross-sectional point cloud {y w ,z w}, the least square method is used to fit the center of the cross section, and the fitting circle equation is:

[0090]

[0091] Where n is the number of points in the cross-sectional point cloud, a, b, c, d, and e are all coefficients. In this embodiment, the coefficients are set as follows:

[0092]

[0093] b=n∑y w z w -∑y w ∑z w

[0094]

[0095] Step 4.2: Calculate the centroid coordinates of the point cloud segment;

[0096] According to the radius r of the fitting circle and the coordinates of the center of the fitting circle (y r ,z r ), calculate the segment of the rotated point cloud {x w ,y w ,z w}Inner center of mass coordinates (x0, y0, z0), the formula is as follows:

[0097]

[0098] y0=y r

[0099] z0=z r

[0100] Where α0 is the linear tangent angle of the point cloud segment, x A is the x-axis coordinate value of point A.

[0101] Step 4.3: Calculate the center coordinates of the point cloud segment;

[0102] Rotate the centroid coordinates (x0, y0, y0) in the xz-axis plane back to the initial point cloud fragment {x i ,y i ,zi}, and obtain the center coordinates (x c ,y c ,z c );

[0103] The rotation takes point A as the reference point, and the rotation angle is -α0. The formula is as follows:

[0104] x c =(x0-x A )cos(-α)-(z0-z A )sin(-α)+x A

[0105] y c =y0

[0106] z c =(x0-x A )sin(-α)+(z0-z A )cos(-α)+z A

[0107] Step 5: Calculate the cable length. Use the center coordinates of all point cloud segments to calculate the cable length L0 of the 3D laser point cloud. Combined with the anchorage lengths L1 and L2 of the cable in the beam and tower body in the design data, the cable length L of the cable is obtained. The specific steps include the following:

[0108] Step 5.1: Calculate the center coordinates (x c ,y c ,z c ), the center coordinates of all point cloud segments (x c ,y c ,z c ) form the precise linear coordinate points of the inclined cable {x ci ,y ci ,z ci}, the calculation formula is as follows:

[0109]

[0110] Where m is the number of point cloud segments.

[0111] Step 5.2: According to the linear coordinate point {x ci ,y ci ,z ci}, calculate the cable length L0 of the 3D laser point cloud part, the formula is as follows:

[0112]

[0113] Step 5.3: Obtain the anchorage lengths L1 and L2 of the cable in the beam and tower body according to the design data, and calculate the cable length L of the cable as follows:

[0114] L=L0+L1+L2

[0115] In the formula, {x ci ,y ci ,z ci} and {x c(i+1) ,y c(i+1) ,z c(i+1)} are the center coordinates of the i-th and i+1-th inclined cable linear coordinate points respectively.

[0116] An embodiment of the present invention also provides an electronic device, comprising: one or more processors; a storage device on which one or more programs are stored; when the one or more programs are executed by the one or more processors, the one or more processors implement the method for measuring the length of a cable based on a three-dimensional laser point cloud described in any of the above embodiments.

[0117] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the steps of any one of the methods for measuring the length of a stayed cable based on a three-dimensional laser point cloud in the above-mentioned embodiments are implemented.

[0118] In summary, the present invention applies the three-dimensional laser scanning technology to the measurement of the length of the inclined cable, and based on the three-dimensional laser point cloud model, realizes the rapid and efficient measurement of the length of the inclined cable without contacting the specific inclined cable structure.

[0119] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for measuring the length of a stay cable based on three-dimensional laser point cloud, characterized in that: The steps include: Step 1: Use a 3D laser scanner to scan the cable surface of the cable-stayed bridge to obtain a point cloud model {x, y, z} of a single cable; Step 2: Segment the point cloud model {x, y, z} of a single cable to obtain multiple point cloud segments {x i ,y i ,z i }; Step 3: Segment the point cloud {x i ,y i ,z i } to transform the coordinates and obtain the cross-sectional point cloud {y w ,z w }; Step 4: For the cross-section point cloud {y w ,z w } Fit the coordinates of the center of the cross section and calculate the point cloud segment {x i ,y i ,z i }'s center coordinates; Step 5: Use the center coordinates of all point cloud segments to calculate the cable length L0 of the 3D laser point cloud part, and combine the anchorage lengths L1 and L2 of the cable inside the beam and tower body in the design data to obtain the cable length L of the cable.

2. The method for measuring the length of a stay cable based on three-dimensional laser point cloud according to claim 1, characterized in that: Step 1 specifically includes the following steps: Step 1.1: Determine the location of the ground 3D laser scanner station according to the size and accuracy requirements of the cable to be measured on the cable-stayed bridge; Step 1.2: Use a 3D laser scanner to scan the cable surface of the cable-stayed bridge to collect point cloud data of the cable surface. The cable scanning range is the cable between the intersection of the cable and the main beam and the intersection with the main tower; Step 1.3: After scanning the cable surface to be measured and obtaining the cable surface point cloud data, preprocess the cable surface point cloud data and convert the cable surface point cloud data into a direction in which the x-axis corresponds to the length of the cable, the y-axis corresponds to the horizontal direction perpendicular to the length of the cable, and the z-axis corresponds to the height of the cable. The point cloud model {x, y, z} of a single cable is extracted from the cable surface point cloud data.

3. The method for measuring the length of a stay cable based on three-dimensional laser point cloud according to claim 1, characterized in that: In step 2, the cable shape is fitted by multiple straight lines, and the cable point cloud data is divided into multiple straight line point cloud segments. In the cable point cloud model {x, y, z}, the point cloud segment {x i ,y i ,z i },as follows: Where m is the number of point cloud segments, rounded up, i = 1, 2, ..., m; x max is the maximum value of x in the point cloud model {x, y, z}; x min It is the minimum value of x in the point cloud model {x, y, z}.

4. The method for measuring the length of a stay cable based on three-dimensional laser point cloud according to claim 3, characterized in that: Step 3 specifically includes the following steps: Step 3.1: Use a cubic polynomial to fit the point cloud model of the entire cable to obtain an approximate linear curve of the cable. The cubic polynomial equation is expressed as follows: z=Ax 3 +Bx 2 +Cx+D Where A, B, C, and D are polynomial coefficients, and x and z are x and z in {x, y, z}; Step 3.2: Calculate the linear tangent angle α0 of the point cloud segment according to the cubic polynomial equation as follows: α0=arctan(3Ax A 2 +2Bx A +C) Among them, x A Segment the point cloud {x i ,y i ,z i }The minimum value of the z-axis corresponds to the x-axis coordinate value of point A; Step 3.3: Segment the point cloud {x i ,y i ,z i }Rotate α0 with point A as the reference point in the xz-axis plane to obtain the rotated point cloud fragment {x w ,y w ,z w }, project the rotated point cloud fragment onto the yz-axis plane to obtain the cross-sectional point cloud {y w ,z w }, the calculation is as follows: and w =and i z w =(x i -x A )sinα0+(z i -z A )cosα0+z A Among them, z A Segment the point cloud {x i ,y i ,z i }The minimum z-axis value corresponds to the z-axis coordinate value of point A.

5. The method for measuring the length of a stay cable based on three-dimensional laser point cloud according to claim 4, characterized in that: Step 4 specifically includes the following steps: Step 4.1: According to the cross-section point cloud {y w ,z w }, the least square method is used to fit the cross-section circle center, the radius of the fitting circle is r, and the coordinates of the fitting circle center are (y r ,z r ); Step 4.2: Calculate the segment {x w ,y w ,z w The coordinates of the centroid (x0, y0, z0) are calculated as follows: y0=y r z0=z r Step 4.3: Rotate the centroid coordinates (x0, y0, y0) in the xz-axis plane back to the initial point cloud fragment {x i ,y i ,z i } position, obtain the center coordinates (x c ,y c ,z c ), the rotation takes point A as the reference point, the rotation angle is -α0, and the formula is as follows: x c =(x0-x A )cos(-α)-(z0-z A )sin(-a)+x A y c =y0 With c =(x0-x A )sin(-α)+(z0-z A )cos(-α)+z A 。 6. The method for measuring the length of a stay cable based on three-dimensional laser point cloud according to claim 5, characterized in that: In step 4.1, the least squares method is used to fit the center of the cross section, and the fitting circle equation is as follows: Where n is the number of points in the cross-sectional point cloud, and a, b, c, d, and e are all fitting coefficients.

7. The method for measuring the length of a stay cable based on three-dimensional laser point cloud according to claim 5, characterized in that: Step 5 specifically includes the following steps: Step 5.1: Calculate the center coordinates (x c ,y c ,z c ), the center coordinates of all point cloud segments (x c ,y c ,z c ) to form the precise linear coordinate points of the inclined cable {x ci ,y ci ,z ci }, the formula is as follows: Step 5.2: According to the linear coordinate point {x ci ,y ci ,z ci }Calculate the cable length L0 of the 3D laser point cloud part, the formula is as follows: Step 5.3: Obtain the anchorage length of the cable in the beam and tower body according to the design data, and calculate the cable length L of the cable. The formula is as follows: L=L0+L1+L2 Among them, L1 is the anchorage length of the inclined cable inside the beam body, and L2 is the anchorage length of the inclined cable inside the tower body.

8. An electronic device, characterized in that: include: one or more processors; a storage device having one or more programs stored thereon; When the one or more programs are executed by the one or more processors, the one or more processors implement the method for measuring the length of a stayed cable based on three-dimensional laser point cloud as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the program is executed by a processor, the steps in the method for measuring the length of a stay cable based on a three-dimensional laser point cloud as described in any one of claims 1 to 7 are implemented.

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