CN109900338B - Method and device for measuring volume of pavement pit - Google Patents
Method and device for measuring volume of pavement pit Download PDFInfo
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Abstract
The invention discloses a method and a device for measuring the volume of a pavement pit, which are used for dividing pavement three-dimensional point cloud to obtain the three-dimensional point cloud of a pit area; projecting the three-dimensional point cloud of the pit area to a road plane area to obtain a two-dimensional plane of the pit area; performing triangulation on the two-dimensional plane of the pit area to obtain a plurality of triangular pit two-dimensional planes; back projecting the two-dimensional planes of the triangular pits into a three-dimensional space in a direction perpendicular to the road plane area to obtain a plurality of triangular prisms; calculating the volume of each triangular prism, and summing to obtain the volume of the pit area; the volume measurement method provided by the invention aims at the characteristics of non-closeness of the point cloud of the pit slot, the problem of open pit slot volume measurement is solved for the first time, the original physical form of the pit slot is accurately restored by the three-dimensional point cloud, and the error is smaller in the algorithm processing process, so that the volume measurement accuracy is higher.
Description
Technical Field
The invention relates to a method and a device for measuring a road surface pit, in particular to a method and a device for measuring the volume of the road surface pit.
Background
The road pits refer to pits formed by local aggregate loss of the road surface caused by road surface aging, rain and snow erosion and vehicle loss, and are serious road surface diseases faced by road maintenance. The road pit not only causes jolt and discomfort to driving, but also has potential safety hazard, and particularly under the condition of measuring high-speed driving on a highway, the pit may cause serious traffic accidents.
In the daily patrol management of the highway and the regular information collection process of the pavement pits, the accurate pit geometric information is obtained, which is of great help for the road maintenance construction operation. In the future, the pavement maintenance system is bound to be automated and intelligentized to improve the efficiency and reduce the maintenance cost, and the pit volume is taken as important road maintenance data and is the key point of attention of intelligent maintenance equipment. The accurate pit volume measuring method has important application value for accurately acquiring the road pit information and providing an accurate filling volume basis for intelligent road maintenance equipment.
Some existing automatic detection technologies for pavement pits in the market can only detect the area and depth information of the pits. Due to the randomness, the non-closeness and the irregularity of the pit shape, the three-dimensional volume information of the pit cannot be accurately obtained, and no good method for measuring the volume of the road pit exists in the market. The accurate acquisition of the volume of the road pit has obvious advantages in the automation of equipment maintenance and the automatic filling of roads.
Disclosure of Invention
The invention aims to provide a method and a device for measuring the volume of a pit on a road surface, which are used for solving the problem that the measuring method and the device in the prior art cannot obtain the accurate pit volume.
In order to realize the task, the invention adopts the following technical scheme:
a method for measuring the volume of a pit on a road surface, wherein the road surface comprises a road plane area and a pit area, and the method is implemented according to the following steps:
step 2, segmenting the road surface three-dimensional point cloud to obtain a pit and groove area three-dimensional point cloud;
step 3, projecting the three-dimensional point cloud of the pit area to the direction of the road plane area to obtain a two-dimensional plane of the pit area;
step 4, performing triangulation on the two-dimensional plane of the pit area to obtain a plurality of triangular pit two-dimensional planes;
step 5, back projecting the two-dimensional planes of the triangular pits into a three-dimensional space in a direction perpendicular to the road plane area to obtain a plurality of triangular prisms;
the heights of the three sides of the triangular prism are the depth values of three corresponding three-dimensional points in the three-dimensional point cloud of the pit groove area before the projection in the step 3 of the three vertexes in the triangular pit groove two-dimensional plane obtained in the step 4;
and 6, calculating the volume of each triangular prism, and summing to obtain the volume of the pit area.
Further, the step 2 specifically includes:
step 21, performing pretreatment operation on the road surface three-dimensional point cloud to obtain a pretreated three-dimensional point cloud, wherein the pretreatment operation comprises down-sampling operation and filtering operation which are sequentially executed;
step 22, deleting all three-dimensional points with the depth values smaller than a depth threshold value according to the depth value of each three-dimensional point in the preprocessed three-dimensional point cloud to obtain the three-dimensional point cloud of the non-road plane area, wherein the depth threshold value is twice of the average value of the depth values of all three-dimensional points in the preprocessed three-dimensional point cloud;
step 23, in the three-dimensional point cloud of the non-road plane area, taking the three-dimensional point with the maximum depth value as a seed point, and obtaining the three-dimensional point cloud of the initial pit and groove area by adopting an area growing method;
step 24, processing all three-dimensional points in the three-dimensional point cloud of the initial pit area by adopting an edge searching method to obtain a plurality of three-dimensional points to form the pit area edge;
and 25, collecting all three-dimensional points within the edge of the pit area to obtain the three-dimensional point cloud of the pit area.
Further, the down-sampling operation in step 21 is voxel grid filtering.
Further, in the step 22, according to the depth value of each three-dimensional point in the preprocessed three-dimensional point cloud, all three-dimensional points of which the depth values are smaller than the depth threshold are deleted by using a RANSAC algorithm, so as to obtain the three-dimensional point cloud of the non-road plane area.
Further, when all three-dimensional points in the three-dimensional point cloud of the initial pit and groove area are processed by adopting the edge searching method, one vertex of the three-dimensional point cloud of the initial pit and groove area is used as an initial three-boundary point, and a plurality of three-dimensional points are sequentially obtained by utilizing the maximum angle principle of the boundary points to form the edge of the pit and groove area.
Further, the Delaunay triangulation method is adopted to conduct triangulation on the two-dimensional plane of the pit groove area, and a plurality of triangular pit groove two-dimensional planes are obtained.
Further, after the Delaunay triangulation method is adopted to triangulate the two-dimensional plane of the pit area, a plurality of triangular two-dimensional planes are obtained, and then the triangular two-dimensional planes with three vertexes coinciding with the edges of the pit area are deleted from the plurality of triangular two-dimensional planes, so that a plurality of triangular two-dimensional pit planes are obtained.
A road surface pit volume measuring device is used for realizing the road surface pit volume measuring method and comprises a road surface three-dimensional point cloud obtaining module, a pit three-dimensional point cloud segmentation module and a pit volume calculating module;
the road surface three-dimensional point cloud acquisition module is connected with the pit slot three-dimensional point cloud segmentation module and is used for acquiring road surface three-dimensional point clouds in a direction parallel to the road plane area;
the pit three-dimensional point cloud segmentation module and the pit volume calculation module are used for segmenting the road surface three-dimensional point cloud to obtain the pit area three-dimensional point cloud;
the pit volume calculation module is used for projecting the three-dimensional point cloud of the pit area to a road plane area to obtain a two-dimensional plane of the pit area;
the triangular pit two-dimensional plane is used for carrying out triangular segmentation on the two-dimensional plane of the pit area to obtain a plurality of triangular pit two-dimensional planes;
the three-dimensional space is also used for back projecting the two-dimensional planes of the triangular pits in the direction vertical to the road plane area to obtain a plurality of triangular prisms;
and calculating the volume of each triangular prism, and summing to obtain the volume of the pit area.
Furthermore, the pit three-dimensional point cloud segmentation module and the pit volume calculation module are both intelligent mobile devices.
Furthermore, the intelligent mobile device is a mobile phone.
Compared with the prior art, the invention has the following technical effects:
1. when the pavement pit volume measuring method provided by the invention is used for dividing the pit area, the wrong and redundant point clouds are removed by methods such as filtering and downsampling, the number of three-dimensional points in the three-dimensional point cloud is reduced, and the dividing speed of the pit area is effectively improved;
2. when the pavement pit volume measuring method and the pavement pit volume measuring device are used for dividing the pit area, the road plane area is removed by using the depth threshold, the non-road plane area is reserved, the approximate area of the pit can be quickly divided, the complexity of the dividing method is reduced, and the dividing speed is increased;
3. when the pit area is divided, the method and the device for measuring the volume of the pavement pit firstly adopt the area generation method to obtain the initial pit area, and then use the edge search method to obtain the edge of the complete pit area on the basis, thereby improving the integrity and the accuracy of pit division;
4. when the pavement pit volume measuring method and the pavement pit volume measuring device are used for dividing the pit area, the boundary point maximum angle principle is utilized to sequentially obtain a plurality of three-dimensional points to form the edge of the pit area, so that the accuracy of pit division is further improved, and a good data basis is provided for accurate calculation of the pit volume;
5. when the pavement pit volume measuring method and the device provided by the invention are used for calculating the pit volume, the three-dimensional point cloud is firstly mapped on the two-dimensional plane, and the two-dimensional plane is divided and then reversely mapped back to the three-dimensional space, so that compared with the method that the three-dimensional point cloud is directly divided, the method has low complexity and high real-time performance;
6. when the pavement pit volume measuring method and the pavement pit volume measuring device are used for calculating the pit volume, the high-precision three-dimensional point cloud is used for measuring the three-dimensional volume of the pit, the three-dimensional point cloud accurately restores the original physical form of the pit, and the error is small in the algorithm processing process, so that the pavement pit volume measuring method and the device have high volume measuring accuracy;
7. the method and the device for measuring the volume of the pavement pit slot solve the problem of open pit slot volume measurement for the first time aiming at the characteristics of point cloud non-closeness of the pit slot when the volume of the pit slot is calculated.
Drawings
FIG. 1 is a flow chart of a method for measuring the volume of a pavement pit provided by the invention;
FIG. 2 is a left and right camera image for reconstructing a three-dimensional point cloud of a road surface according to an embodiment of the present invention;
FIG. 3 is a three-dimensional point cloud of a roadway collected in one embodiment of the present invention;
FIG. 4 is a three-dimensional point cloud of pit areas obtained by segmentation in an embodiment of the present invention;
fig. 5 is a two-dimensional planar image of a pit area obtained in an embodiment of the present invention;
FIG. 6 is a two-dimensional planar image of a pit area after triangulation in one embodiment of the invention;
FIG. 7 is an image of a triangular prism obtained in one embodiment of the present invention;
FIG. 8 is a simulated pit image provided in an embodiment of the invention;
fig. 9 is a structural view of a pavement pit volume measuring apparatus according to an embodiment of the present invention.
Detailed Description
Three-dimensional point cloud: the camera is composed of a plurality of three-dimensional points, each three-dimensional point has an abscissa value, an ordinate value and a depth value, the origin of a coordinate system is generally the left lens of the camera, and the abscissa value, the ordinate value and the depth value are all positive values.
Boundary point maximum angle principle: in a plurality of adjacent points of a boundary point, the boundary point and any adjacent point have included angles (the included angle does not include other adjacent points), so a plurality of included angles exist, and two adjacent points corresponding to the difference between the largest two included angles are necessarily the boundary points.
Delaunay triangulation method: if a triangulation T of the set of points V contains only Delaunay edges, which are two end points where a circle passes through the Delaunay edges, and no other points in the set of points V are contained in the circle, the set of points or the image can be divided into triangular shapes using the Delaunay triangulation method.
Example one
A method for measuring the volume of a pit on a road surface, wherein the road surface comprises a road plane area and a pit area, as shown in figure 1, the measuring method is carried out according to the following steps:
in this step, a three-dimensional point cloud of a road surface area containing a depression is obtained by using three-dimensional imaging equipment such as a binocular stereo camera, and the three-dimensional point cloud is used as an input of the measurement method provided in this embodiment.
During shooting, the imaging device is taken right opposite to the plane, and the pit recess range is completely covered.
In this embodiment, a three-dimensional point cloud of a road surface obtained by performing three-dimensional reconstruction on left and right camera images of a binocular camera as shown in fig. 2 is shown in fig. 3.
Step 2, segmenting the road surface three-dimensional point cloud to obtain the pit and groove area three-dimensional point cloud;
in the step, when the three-dimensional point cloud is segmented, the existing methods include an euclidean algorithm, a kdTree algorithm and an OcTree algorithm, but when the above algorithms face the three-dimensional point cloud of the road surface, the road surface is uneven, and the three-dimensional point cloud collected by the algorithms contains a large amount of noise.
Optionally, the step 2 specifically includes:
step 21, performing pretreatment operation on the road surface three-dimensional point cloud to obtain a pretreated three-dimensional point cloud, wherein the pretreatment operation comprises down-sampling operation and filtering operation which are sequentially executed;
because the acquired three-dimensional point cloud has large data volume and contains noise, if the three-dimensional point cloud is directly processed, the phenomena of low segmentation speed and poor segmentation effect occur, and therefore in the step, the three-dimensional point cloud is subjected to dimensionality reduction and then filtered.
Optionally, the step 21 is performed according to the following steps:
step 211, down-sampling the three-dimensional point cloud by using a voxel grid filtering method to obtain a down-sampled three-dimensional point cloud;
the method comprises the steps of firstly, conducting down-sampling on three-dimensional point cloud, conducting down-sampling on the three-dimensional point cloud by adopting a voxel grid filtering method so as to reduce redundant data quantity and improve the point cloud processing speed, and can keep details in the depth direction during filtering so as to reduce the detail loss in the depth direction.
The specific process is as follows: a three-dimensional voxel grid is created through input three-dimensional point clouds, the voxel grid is equivalent to a set of a spatial three-dimensional cube, then in each voxel, the gravity centers of all points in the voxel are used for approximately displaying other points in the voxel, therefore, all points in the voxel grid are finally represented by one gravity center point, and after all point clouds are processed according to the voxel grid, downsampling point clouds are obtained, and accurate representation of a sampling point corresponding to a curved surface is obtained.
212, performing direct filtering on the down-sampled three-dimensional point cloud to obtain a direct-filtered three-dimensional point cloud;
in the step, the down-sampled three-dimensional point cloud is filtered, and a through filtering method is adopted, specifically, by setting a depth direction data range of the three-dimensional point cloud, for example, between 0.8 m and 1.2m, the point cloud outside the range is removed as an interference point.
And 213, performing statistical filtering on the three-dimensional point cloud subjected to the direct filtering to obtain a processed three-dimensional point cloud.
In the step, a statistical filtering method is adopted for the three-dimensional point cloud after direct filtering, a statistical analysis is carried out on the neighborhood of each point, some point clouds which do not accord with the standard are removed, isolated redundant point clouds are reduced, the statistical filtering carries out a statistical analysis on the neighborhood of each point, and the points which do not accord with the set standard are trimmed. Specifically, in the present embodiment, a sparse outlier removal method is adopted, based on the calculation of the distance distribution from a point to a neighboring point in the input three-dimensional point cloud. For each three-dimensional point, calculating the average distance from the three-dimensional point to all adjacent points, and obtaining the result of Gaussian distribution, wherein the shape of the Gaussian distribution is determined by the mean value and the standard deviation, and the three-dimensional points with the average distance outside the standard range (defined by the average value and the variance of the global distances) are outliers and are removed from the three-dimensional point cloud.
According to the pavement pit volume measuring method, when the pit area is divided, the road plane area is removed by using the depth threshold, the non-road plane area is reserved, the approximate area of the pit can be quickly divided, the complexity of the dividing method is reduced, and the dividing speed is increased.
Step 22, deleting all three-dimensional points with the depth values smaller than a depth threshold value according to the depth value of each three-dimensional point in the preprocessed three-dimensional point cloud to obtain the three-dimensional point cloud of the non-road plane area, wherein the depth threshold value is twice of the average value of the depth values of all three-dimensional points in the preprocessed three-dimensional point cloud;
in this step, since the three-dimensional point cloud is obtained in parallel to the plane area when being obtained, the depth values in the three-dimensional point cloud of the plane area should be the same, and the plane three-dimensional point cloud can be found by this feature.
Preferably, according to the depth value of each three-dimensional point in the preprocessed three-dimensional point cloud, deleting all three-dimensional points of which the depth values are smaller than a depth threshold value by using a RANSAC algorithm to obtain the three-dimensional point cloud of the non-road plane area.
In this step, when the RANSAC algorithm is used to extract the road plane, a depth threshold is set, and the depth threshold is set according to the thickness of the road plane, for example, a road plane with a depth of 2mm is to be segmented, in the measurement method provided in this embodiment, all points within a depth of 2mm near the road plane will be taken as three-dimensional points of the road plane, which is equivalent to cutting the three-dimensional point cloud in the depth direction to cut the road plane.
In this step, while the planar point cloud is extracted, other non-planar part point clouds (including pit and slot point clouds) are segmented. Under normal conditions, due to noise and interference of cloud points without matching error points, complete and accurate pit slots can not be provided, and no part of point clouds need to be further processed.
Therefore, before the step 23 is executed, firstly, the three-dimensional point cloud of the non-road plane area is secondarily filtered in a statistical filtering manner to obtain the filtered three-dimensional point cloud of the non-road plane area, and the filtered three-dimensional point cloud of the non-road plane area is input to the step 23.
In the step, a statistical filtering mode is adopted again during secondary filtering, filtering parameters are set, useless isolated point clouds with small ranges are removed, the total number of three-dimensional points contained in each point cloud within a certain distance is set, if the total number of three-dimensional points is smaller than a set minimum three-dimensional point total threshold value, the point clouds are considered to be isolated point clouds, and if the total number of three-dimensional points is larger than a set maximum three-dimensional point total threshold value, the point clouds are also considered to be invalid three-dimensional point clouds. For example, counting the number of three-dimensional points within 5 centimeters around a certain three-dimensional point, if the counted result is less than 500, regarding the three-dimensional point and all the three-dimensional points within 5 centimeters around the three-dimensional point as isolated point clouds, and if the counted result is greater than 50000, regarding as an invalid point cloud cluster exceeding the theoretical pit data amount, and removing the invalid point cloud cluster, in fig. 3, there are some small pit areas beside the largest pit area, and in this step, the small pit areas are removed, and the small pit areas are the isolated point clouds.
Step 23, in the three-dimensional point cloud of the non-road plane area, taking the three-dimensional point with the maximum depth value as a seed point, and obtaining the three-dimensional point cloud of the initial pit and groove area by adopting an area growing method;
in this step, a depth threshold set in downsampling is used as a distance threshold in the region growing method, a three-dimensional point with the maximum depth value is used as a starting point, a point within the range of the distance threshold is searched, the newly searched point is iterated to be used as a starting point, searching is continued until a three-dimensional point at the edge of the divided pit area is searched, and an initial pit area three-dimensional point cloud is obtained.
In order to improve the accuracy of the segmentation, in this embodiment, the initial pit and trench area three-dimensional point cloud is subjected to an edge search again to obtain a complete pit and trench area edge.
Step 24, processing all three-dimensional points in the three-dimensional point cloud of the initial pit area by adopting an edge searching method to obtain a plurality of three-dimensional points to form the pit area edge;
in this step, the method for edge search may be a method for depth threshold detection, a method for gradient difference threshold detection, or the like, but when facing the pit area in the road surface, these methods in the prior art have a slope at the edge of the pit, and therefore none of the methods using the prior art for threshold detection can find the edge of the pit area well, resulting in inaccurate segmentation of the pit area and inaccurate calculation of the pit volume.
Therefore, in this embodiment, an iterative edge search method that is continuously approximated is provided, where a vertex of the three-dimensional point cloud of the initial pit and trench area is used as an initial boundary point, and a plurality of three-dimensional points are sequentially obtained by using a boundary point maximum angle principle to form a pit and trench area edge.
Specifically, the method comprises the following steps:
step I, clearing a boundary three-dimensional point set;
step II, finding a plurality of adjacent three-dimensional points around the initial boundary point by adopting a k-adjacent algorithm;
in this step, specifically, the initial boundary point is used as a sphere center, a distance threshold is used as a radius of the sphere, a selection sphere is established, all three-dimensional points in the selection sphere are used as adjacent three-dimensional points, a plurality of adjacent three-dimensional points are obtained, and the distance threshold is twice of an average value of depth values of all three-dimensional points in the three-dimensional point cloud after secondary filtering;
step III, calculating an included angle between each adjacent three-dimensional point and the initial boundary point to obtain a plurality of included angle values;
IV, arranging all included angle values in a descending order according to the sizes, and calculating the angle difference between two adjacent included angle values to obtain a plurality of angle differences;
v, selecting the maximum angle difference from all the angle differences, and taking two adjacent three-dimensional points corresponding to two included angle values corresponding to the maximum angle difference as two boundary three-dimensional points;
VI, if the boundary three-dimensional point set is empty, executing the VIII; otherwise, executing VII;
step VII, judging whether one of the two boundary three-dimensional points obtained in the step V is in the boundary three-dimensional point set;
if one boundary three-dimensional point is in the boundary three-dimensional point set, taking another boundary three-dimensional point which is not in the boundary three-dimensional point set as a new initial boundary point, and then putting the new boundary point into the boundary three-dimensional point set to execute the step IX;
if the two boundary three-dimensional points are in the boundary three-dimensional point set, selecting a point which is farthest away from the initial boundary point as a new initial boundary point;
otherwise, firstly putting the two boundary three-dimensional points into a boundary three-dimensional point set, then respectively calculating the angle values between the two boundary three-dimensional points and the initial boundary point, and executing the step IX after selecting the boundary three-dimensional point with the largest angle value as a new initial boundary point;
step IX, taking the new initial boundary point as input, repeating the steps II to IX until the new initial boundary point obtained at this time is one vertex of the three-dimensional point cloud of the initial pit and groove area selected when the step II is executed for the first time, and then executing the step X;
in the embodiment, the boundary point maximum angle principle is utilized to sequentially obtain a plurality of three-dimensional points to form the edge of the pit area, so that the accuracy of pit division is further improved, and a good data basis is provided for accurate calculation of the pit volume.
And step X, extracting all boundary three-dimensional points in the boundary three-dimensional point set from the initial pit area three-dimensional point cloud to obtain a plurality of three-dimensional points to form the pit area edge.
In the step X, after all boundary three-dimensional points in the boundary three-dimensional point set are extracted from the initial pit area three-dimensional point cloud, the boundary three-dimensional points are sparse boundary three-dimensional points, and if the pit area three-dimensional point cloud is directly obtained through the sparse boundary three-dimensional points, the pit area three-dimensional point cloud may have noise points, that is, the division is inaccurate, so in this embodiment, all boundary three-dimensional points are densified to obtain a pit area edge composed of a plurality of three-dimensional points.
In this step, all boundary three-dimensional points are densified by interpolation, but in this embodiment, in order to improve the accuracy of densification, the divided pit areas can be more complete and accurate, and boundary densification is to evolve sparse boundary points into dense point clouds, that is, to add boundary points on a sparse point connection to the boundary point clouds.
Specifically, in this embodiment, all the boundary three-dimensional points are densified according to the following steps:
step A, finding two adjacent boundary three-dimensional points from all boundary three-dimensional points as an end point and an end point respectively;
step B, establishing a selection sphere by taking the end point as the sphere center and the distance threshold value as the radius of the sphere, and taking all three-dimensional points in the selection sphere as adjacent boundary three-dimensional points to obtain a plurality of adjacent boundary three-dimensional points;
the distance threshold in this step is the same as the distance threshold in step II.
Step C, calculating the distance between all the adjacent boundary three-dimensional points and a straight line consisting of an end point and a terminal point to obtain the distance values of the plurality of adjacent boundary three-dimensional points;
step D, using the distance value smaller than the dense distance threshold value corresponding to the adjacent boundary three-dimensional point as a dense boundary three-dimensional point to obtain a plurality of dense boundary three-dimensional points, wherein the dense distance threshold value is the density value of the three-dimensional point cloud after secondary filtering;
e, repeating the steps A to E until all the boundary three-dimensional points are used as end points, and obtaining a plurality of dense boundary three-dimensional points;
and F, combining all the dense boundary three-dimensional points with all the boundary three-dimensional points to obtain the edge of the pit area formed by a plurality of three-dimensional points.
And 25, collecting all three-dimensional points within the edge of the pit area to obtain the three-dimensional point cloud of the pit area.
Therefore, the pit area edge is the edge composed of the dense boundary points and all the boundary three-dimensional points obtained in step F, and all the three-dimensional points within the edge are taken out, including the edge, to obtain the three-dimensional point cloud of the pit area.
In this embodiment, for the three-dimensional point cloud of the road surface shown in fig. 3, the pit-groove point cloud in the three-dimensional point cloud of the road surface in fig. 3 occupies a small part of the three-dimensional point cloud of the road surface, but it can be seen in fig. 3 that the three-dimensional point cloud data which is not processed is very huge, and by adopting the edge search and edge densification method provided in this embodiment, the pit-groove area shown in fig. 4 is obtained, and the edge of the pit-groove area is composed of dense three-dimensional boundary points and three-dimensional boundary points.
When the pavement pit volume measuring method provided by the invention is used for dividing the pit area, firstly, the area generating method is adopted to obtain the initial pit area, and on the basis, the edge searching method is used to obtain the edge of the complete pit area, so that the completeness and the accuracy of pit division are improved, and the method for densifying the sparse edge is provided to obtain a more accurate pit area.
If the three-dimensional point cloud of the pit area is directly segmented, the volumes of all the segmented parts are added, the operation speed of the measuring method is too low due to too large data volume, and the whole measuring method has no real-time performance, so in the embodiment, the three-dimensional point cloud is projected onto a two-dimensional plane, the area of the plane is calculated, and then the volume is further obtained.
Step 3, projecting the three-dimensional point cloud of the pit area to a road plane area to obtain a two-dimensional plane of the pit area;
in the step, the three-dimensional point cloud of the divided pit area is mapped to an X-Y two-dimensional plane taking a road plane as a reference, and the origin of a coordinate system is the projection of the optical center of the left camera of the binocular camera on the road plane.
In this embodiment, the coordinates of the three-dimensional point a in the space are (x1, y1, z1), the coordinates of the three-dimensional point B in the space are (x2, y2, z2), the coordinates of the three-dimensional point C in the space are (x3, y3, z3), and projecting the three-dimensional point C in the road plane area is equivalent to removing the z-axis coordinates, so that three two-dimensional points are obtained, the coordinates of the point a in the two-dimensional plane are (x1, y1), the coordinates of the vertex B in the two-dimensional plane are (x2, y2), and the coordinates of the vertex C in the two-dimensional plane are (x3, y 3).
In the present embodiment, a two-dimensional plane image of the pit area is obtained as shown in fig. 5.
Step 4, performing triangulation on the two-dimensional plane of the pit area to obtain a plurality of triangular pit two-dimensional planes;
optionally, the Delaunay triangulation method is adopted to triangulate the two-dimensional plane of the pit area, so as to obtain a plurality of triangular pit two-dimensional planes.
In this step, a Delaunay triangulation method is adopted to grid the two-dimensional plane of the pit area, so that the minimum internal angle is maximized, and it cannot be guaranteed that the finally obtained triangles are all in the pit projection. When the crater is concave, as shown in fig. 6, the fully black area is inside the crater, and there are some triangles outside the crater edge divided by the Delaunay triangulation method, which do not belong to the triangles to be calculated.
Therefore, in order to eliminate the triangle outside the pit area and ensure the accuracy of the calculation of the pit volume, after the two-dimensional plane of the pit area is triangulated by a Delaunay triangulation method, a plurality of triangular two-dimensional planes are obtained, and then the triangular two-dimensional planes with three vertexes coinciding with the edges of the pit area are deleted from the plurality of triangular two-dimensional planes, so that the plurality of triangular two-dimensional pit planes are obtained.
In the present embodiment, three vertices of a triangle all belong to boundary points; under normal conditions, at least one of three vertexes of the triangle belongs to the interior of the hollow, theoretically, all outer triangles can be excluded by the principle, but in order to prevent dense boundary points from being extracted incompletely; and if the two vertexes of the triangle belong to the boundary points and the distance exceeds ten times of the boundary points, judging that the triangle is also an outer triangle, and removing all the outer triangles to obtain a plurality of triangular pit two-dimensional planes.
Step 5, back projecting the two-dimensional planes of the triangular pits into a three-dimensional space in a direction perpendicular to the road plane area to obtain a plurality of triangular prisms;
the heights of three sides of the triangular prism are the depth values of three corresponding three-dimensional points in the three-dimensional point cloud of the pit groove area before the projection in the step 3 of three vertexes in the triangular pit groove two-dimensional plane obtained in the step 4 respectively;
in this embodiment, the three vertices of the triangle are A, B and C, where the coordinates of the vertex a in the two-dimensional plane are (x1, y1), the coordinates of the vertex B in the two-dimensional plane are (x2, y2), and the coordinates of the vertex C in the two-dimensional plane are (x3, y3), and after the three vertices are back-projected, the three vertices have spatial information, i.e., depth values, which are the depth values of the corresponding three-dimensional points when the three vertices are not projected onto the two-dimensional plane, i.e., the coordinates of the vertex a in space are (x1, y1, z1), the coordinates of the vertex B in space are (x2, y2, z2), and the coordinates of the vertex C in space are (x3, y3, z 3).
And 6, calculating the volume of each triangular prism, and summing to obtain the volume of the pit area.
In this step, as shown in fig. 7, a triangle is segmented in step 4, and a triangular prism is obtained after back projection, three vertices of the top surface of the triangular prism are A, B and C, coordinates of vertex a in space are (x1, y1, z1), coordinates of vertex B in space are (x2, y2, z2), and coordinates of vertex C in space are (x3, y3, z3), and it can be seen from the figure that the triangular prism is not a regular triangular prism, the top surface is an inclined surface, and the bottom surface is a road plane.
In this step, the height z closest to the road surface is taken as the height h of the standard triangular prism for division, and as shown by the broken line in fig. 7, in this example, the depth value of the vertex a is selected as the height h of the triangular prism, which is z 1.
Wherein the area of the triangle obtained by dividing in step 4 is:
S＝(1/2)|(x2-x1)*(y3-y1)-(x3-x1)*(y2-y1)|
volume v of standard triangular prismp＝S*h。
Secondly, calculating the volume of a tetrahedron on the standard triangular prism, in the step, knowing the three-dimensional data of three-dimensional points, and obtaining the three-dimensional data of the other two vertexes of the tetrahedron by making an auxiliary surface, namelyObtaining the area v of a tetrahedront。
The volume of a triangular prism is then: v. ofi＝vp+vt。
In order to obtain an accurate pit volume, in the present embodiment, the area of the plurality of triangles obtained in step 4 is used as the bottom, the average value of all three-dimensional points twice as high as that in step 22 is used as the height, the depth values of the plurality of standard triangular prisms are obtained again, and then the pit compensation volume is obtained by summing up the depth values of the plurality of standard triangular prisms, and the pit compensation volume obtained in the above step is calculated on the basis of the area of the plurality of triangles obtained in step 4, and obtaining the final accurate pit area volume.
The volume of the simulated pit slot shown in fig. 8 is calculated by using the volume measurement method provided in the present embodiment, where the unit of each coordinate axis is m, the validity of the volume measurement method is verified, and theoretically, the volume of the hemisphere is 2.094395102393195m3By adopting the steps 3 to 6 provided in the embodiment, the volume of the hemisphere is calculated to be 2.072184805179722m3In the embodiment, the volume calculation method adopts an internal approximation method, so that the obtained volume is smaller, but the calculation requirement on the pit volume in actual operation is met, so that the road pit volume calculation method provided by the invention has smaller error and higher accuracy.
In addition, the method for measuring the volume of the pavement pits is not only suitable for measuring the volume of the pits on the pavement, but also suitable for measuring the volume of the pits with pits recessed in all planes.
Example two
As shown in fig. 9, in the present embodiment, a road surface pit volume measuring apparatus is disclosed, which is used for implementing the road surface pit volume measuring method in the first embodiment, and the apparatus includes a road surface three-dimensional point cloud obtaining module, a pit three-dimensional point cloud dividing module, and a pit volume calculating module;
the road surface three-dimensional point cloud acquisition module is connected with the pit slot three-dimensional point cloud segmentation module and is used for acquiring road surface three-dimensional point cloud in a direction parallel to the road plane area;
the pit three-dimensional point cloud segmentation module and the pit volume calculation module are used for segmenting the road surface three-dimensional point cloud to obtain a pit area three-dimensional point cloud;
the pit volume calculation module is used for projecting the three-dimensional point cloud of the pit area to the road plane area to obtain a two-dimensional plane of the pit area;
the triangular pit two-dimensional plane dividing device is also used for carrying out triangular division on the two-dimensional plane of the pit area to obtain a plurality of triangular pit two-dimensional planes;
the three-dimensional space is also used for back projecting the two-dimensional planes of the triangular pits in the direction vertical to the road plane area into the three-dimensional space to obtain a plurality of triangular prisms;
and calculating the volume of each triangular prism, and summing to obtain the volume of the pit area.
Optionally, the pit three-dimensional point cloud segmentation module comprises a pit three-dimensional point cloud preprocessing module, a pit three-dimensional point cloud preliminary segmentation module and a pit three-dimensional point cloud re-segmentation module;
the pit three-dimensional point cloud preprocessing module is connected with the pit three-dimensional point cloud preliminary segmentation module and is used for preprocessing the road surface three-dimensional point cloud to obtain a preprocessed three-dimensional point cloud, and the preprocessing operation comprises down-sampling operation and filtering operation which are sequentially executed;
the pit three-dimensional point cloud primary segmentation module is connected with the pit three-dimensional point cloud re-segmentation module and is used for deleting all three-dimensional points with the depth values smaller than a depth threshold value according to the depth value of each three-dimensional point in the preprocessed three-dimensional point cloud to obtain the three-dimensional point cloud of the non-road plane area, and the depth threshold value is twice of the average value of the depth values of all the three-dimensional points in the preprocessed three-dimensional point cloud;
the pit three-dimensional point cloud repartitioning module is used for obtaining initial pit area three-dimensional point cloud in a non-road plane area by using a region growing method by taking a three-dimensional point with the maximum depth value as a seed point in the three-dimensional point cloud in the non-road plane area;
the method is also used for processing all three-dimensional points in the three-dimensional point cloud of the initial pit and groove area by adopting an edge searching method by taking one vertex of the three-dimensional point cloud of the initial pit and groove area as an initial three-dimensional point to obtain a plurality of three-dimensional points to form a pit and groove area edge;
and the method is also used for collecting all three-dimensional points within the edge of the pit area to obtain the three-dimensional point cloud of the pit area.
Optionally, the pit three-dimensional point cloud segmentation module and the pit volume calculation module are both intelligent mobile devices.
In this embodiment, in order to acquire the three-dimensional point cloud of the pavement pit and the pit three-dimensional point cloud in real time and process the three-dimensional point cloud of the pavement pit and the pit three-dimensional point cloud in real time to perform segmentation and volume calculation on the three-dimensional point cloud of the pavement pit and the pit three-dimensional point cloud of the pavement pit and.
Preferably, the smart mobile device is a mobile phone.
For more convenient acquisition road surface pit volume, the intelligent mobile device is the cell-phone, and road surface maintenance personnel can directly be connected with road surface three-dimensional point cloud acquisition module (equipment such as binocular camera) with its cell-phone, transmits the road surface three-dimensional point cloud that three-dimensional point cloud acquisition module gathered to the cell-phone in, utilizes cell-phone APP to handle, acquires the pit volume.
Claims (6)
1. A method for measuring the volume of a pit on a road surface is characterized in that the road surface comprises a road plane area and a pit area, and the method is implemented according to the following steps:
step 1, collecting road surface three-dimensional point cloud in a direction parallel to the road plane area;
step 2, segmenting the road surface three-dimensional point cloud to obtain a pit and groove area three-dimensional point cloud;
the step 2 specifically comprises:
step 21, performing pretreatment operation on the road surface three-dimensional point cloud to obtain a pretreated three-dimensional point cloud, wherein the pretreatment operation comprises down-sampling operation and filtering operation which are sequentially executed;
step 22, deleting all three-dimensional points with the depth values smaller than a depth threshold value according to the depth value of each three-dimensional point in the preprocessed three-dimensional point cloud to obtain the three-dimensional point cloud of the non-road plane area, wherein the depth threshold value is twice of the average value of the depth values of all three-dimensional points in the preprocessed three-dimensional point cloud;
step 23, in the three-dimensional point cloud of the non-road plane area, taking the three-dimensional point with the maximum depth value as a seed point, and obtaining the three-dimensional point cloud of the initial pit and groove area by adopting an area growing method;
step 24, processing all three-dimensional points in the three-dimensional point cloud of the initial pit area by adopting an edge searching method to obtain a plurality of three-dimensional points to form the pit area edge;
when all three-dimensional points in the three-dimensional point cloud of the initial pit and pit area are processed by adopting the edge searching method, one vertex of the three-dimensional point cloud of the initial pit and pit area is used as an initial three-boundary point, and a plurality of three-dimensional points are sequentially obtained by utilizing the maximum angle principle of the boundary points to form the pit and pit area edge;
step 25, collecting all three-dimensional points within the edge of the pit area to obtain the three-dimensional point cloud of the pit area;
step 3, projecting the three-dimensional point cloud of the pit area to the direction of the road plane area to obtain a two-dimensional plane of the pit area;
step 4, performing triangulation on the two-dimensional plane of the pit area to obtain a plurality of triangular pit two-dimensional planes;
performing triangulation on the two-dimensional plane of the pit area by adopting a Delaunay triangulation method to obtain a plurality of triangular pit two-dimensional planes;
after the two-dimensional plane of the pit slot area is subjected to triangulation by adopting a Delaunay triangulation method, obtaining a plurality of triangular two-dimensional planes, and then deleting the triangular two-dimensional planes with three vertexes coincident with the edge of the pit slot area from the plurality of triangular two-dimensional planes, so as to obtain a plurality of triangular two-dimensional pit slot planes;
step 5, back projecting the two-dimensional planes of the triangular pits into a three-dimensional space in a direction perpendicular to the road plane area to obtain a plurality of triangular prisms;
the heights of the three sides of the triangular prism are the depth values of three corresponding three-dimensional points in the three-dimensional point cloud of the pit groove area before the projection in the step 3 of the three vertexes in the triangular pit groove two-dimensional plane obtained in the step 4;
and 6, calculating the volume of each triangular prism, and summing to obtain the volume of the pit area.
2. The method according to claim 1, wherein the down-sampling operation in step 21 is voxel grid filtering.
3. The method according to claim 1, wherein in step 22, all three-dimensional points with depth values smaller than a depth threshold are deleted by using a RANSAC algorithm according to the depth value of each three-dimensional point in the preprocessed three-dimensional point cloud, so as to obtain the three-dimensional point cloud of the non-road surface area.
4. A pavement pit volume measuring device is characterized by being used for realizing the pavement pit volume measuring method of any one of claims 1 to 3, and the device comprises a pavement three-dimensional point cloud obtaining module, a pit three-dimensional point cloud segmentation module and a pit volume calculation module;
the road surface three-dimensional point cloud acquisition module is connected with the pit slot three-dimensional point cloud segmentation module and is used for acquiring road surface three-dimensional point clouds in a direction parallel to the road plane area;
the pit three-dimensional point cloud segmentation module and the pit volume calculation module are used for segmenting the road surface three-dimensional point cloud to obtain the pit area three-dimensional point cloud;
the pit volume calculation module is used for projecting the three-dimensional point cloud of the pit area to a road plane area to obtain a two-dimensional plane of the pit area;
the triangular pit two-dimensional plane is used for carrying out triangular segmentation on the two-dimensional plane of the pit area to obtain a plurality of triangular pit two-dimensional planes;
the three-dimensional space is also used for back projecting the two-dimensional planes of the triangular pits in the direction vertical to the road plane area to obtain a plurality of triangular prisms;
and calculating the volume of each triangular prism, and summing to obtain the volume of the pit area.
5. The device for measuring the volume of the pit in the road surface according to claim 4, wherein the three-dimensional point cloud segmentation module and the pit volume calculation module are both intelligent mobile devices.
6. The pavement pit volume measuring device according to claim 5, wherein the smart mobile device is a mobile phone.
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| CN113074631B (en) * | 2021-03-11 | 2023-04-25 | 中国水利水电第七工程局有限公司 | Method for measuring rock-fill dam pit volume by hand-held three-dimensional laser scanning |
| CN113362385A (en) * | 2021-06-21 | 2021-09-07 | 山东产研信息与人工智能融合研究院有限公司 | Cargo volume measuring method and device based on depth image |
| CN113888622A (en) * | 2021-10-14 | 2022-01-04 | 吉旗（成都）科技有限公司 | Method and device for determining cargo volume in carriage, electronic equipment and storage medium |
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