A method and device for detecting elevation accuracy of point cloud flight strip splicing

Abstract

This invention provides a method and apparatus for detecting the elevation accuracy of point cloud flight strip stitching, comprising: moving and searching within the overlapping area of ​​adjacent flight strips using a preset detection plane to obtain a first flight path detection plane and a second flight path detection plane; determining whether the difference in the average point cloud elevation between the first and second flight path detection planes is within a preset threshold range; if so, determining the first flight path detection plane as a valid detection plane for the first flight path and the second flight path detection plane as a valid detection plane with the same name for the second flight path; and calculating the point cloud flight strip stitching elevation error value within the overlapping area of ​​the flight strips based on the first and second average point cloud elevation values. By searching and moving the detection plane within the overlapping area of ​​each flight strip across the entire camera area and setting a point cloud elevation threshold, the effective detection planes for the overlapping area of ​​adjacent flight strips can be automatically found, improving the calculation accuracy and efficiency of the point cloud flight strip stitching elevation error.

Description

Technical Field

[0001] The present invention relates to the field of quality inspection of airborne laser radar point cloud data, and in particular to a method and device for detecting the elevation accuracy of point cloud flight strip splicing. Background Art

[0002] Airborne laser radar mainly relies on detection planes to check the elevation error of point cloud flight strips. The existing method for detecting the elevation error of point cloud flight strips is an internal manual detection method, which mainly involves manually selecting a suitable detection plane in the overlapping area of ​​the flight strips, counting the average point cloud elevation of the detection plane, and calculating the elevation error of the point cloud flight strips. The general operation is as follows: After the aerial photography flight, with the assistance of professional data such as digital line drawings, surface coverage classification data or remote sensing images, find flat areas at the beginning, end, and middle of the overlapping area between flight strips as the accuracy verification area of ​​the flight strip splicing elevation error; select flat feature objects (such as runways, roads, etc.) in the accuracy verification area, manually select the range, calculate the point cloud elevation mean within the frame selection range of the two adjacent flight strips, and use the difference between the point cloud elevation mean values ​​to calculate the root mean square as the basis for determining the elevation accuracy of the flight strip splicing.

[0003] However, the above-mentioned manual detection method in the industry is a sampling detection method, which must rely on the assistance of professional data such as images, and needs to find flat feature objects (such as runways, roads, etc.). Even if feature objects such as roads are found, if there are slopes, it may lead to inaccurate calculation results, and there is a possibility that the local point cloud splicing elevation error exceeds the limit. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a method and device for detecting the elevation accuracy of point cloud flight strip splicing, which can effectively alleviate the problem in the existing point cloud flight strip splicing elevation error detection method that although the overall error in the point cloud flight strip splicing elevation is qualified, there are still many error exceeding limit areas, resulting in inaccurate calculation results, thereby improving the calculation accuracy of the error in the point cloud flight strip splicing elevation.

[0005] In a first aspect, an embodiment of the present invention provides a method for detecting the elevation accuracy of point cloud flight strip stitching, comprising: performing a mobile search in an adjacent flight strip overlapping area through a preset detection plane, and obtaining a first route pending detection plane and a second route pending detection plane in the adjacent flight strip overlapping area; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name for two adjacent routes; determining whether the point cloud elevation average value difference between the first route pending detection plane and the second route pending detection plane is within a preset average value elevation difference threshold range, and if so, determining the first route pending detection plane as a first route valid detection plane, and determining the second route pending detection plane as a second route valid detection plane with the same name; obtaining a first point cloud elevation average value of the first route valid detection plane and a second point cloud elevation average value of the second route valid detection plane with the same name in all adjacent flight strip overlapping areas in the entire shooting area, and calculating the point cloud flight strip stitching elevation error value in the flight strip overlapping area based on the first point cloud elevation average value and the second point cloud elevation average value, so as to determine the point cloud flight strip stitching elevation accuracy.

[0006] Furthermore, the method also includes: determining whether the difference in point cloud elevation average values ​​between the first pending detection plane and the second pending detection plane is within a preset average elevation difference threshold range; if not, there is a point cloud elevation mutation in the pending detection plane with the same name; obtaining the vector range of the pending detection plane with the same name, and determining whether the point cloud elevation mutation is an unreasonable elevation mutation based on images or auxiliary data; if the point cloud elevation mutation is an unreasonable elevation mutation, a problem area is formed based on all pending detection planes with the same name where unreasonable elevation mutations occur, so as to re-solve the point cloud data of the adjacent flight strip where the pending detection plane with the same name is located or enable the airborne laser radar to re-acquire the point cloud data.

[0007] Furthermore, a mobile search is performed in the overlapping area of ​​adjacent air strips by means of a preset detection plane, so as to obtain a first route pending detection plane and a second route pending detection plane in the overlapping area of ​​adjacent air strips; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name of two adjacent routes, and the steps include: obtaining point cloud data in the overlapping area of ​​adjacent air strips; searching and moving with a preset step distance in the first route in the overlapping area of ​​adjacent air strips by means of a preset detection plane to determine the first route pending detection plane in the first route, and obtaining a first vector range of the first route pending detection plane; and extending the first vector range of the first route pending detection plane to the second route in the overlapping area of ​​adjacent air strips to obtain the second route pending detection plane in the second route.

[0008] Furthermore, the preset detection plane is a circular detection plane, and the preset step distance is consistent with the radius of the circular detection plane.

[0009] Furthermore, the step of searching and moving the detection plane at a preset step distance within the first route in the overlapping area of ​​adjacent flight strips to determine the first route pending detection plane within the first route and obtaining the vector range of the first route pending detection plane includes: obtaining a first maximum elevation value and a first minimum elevation value of each detection plane within the first route; judging the detection plane within the first route based on a preset elevation difference threshold; determining that the detection plane is the first route pending detection plane if the first elevation value difference between the first maximum elevation value and the first minimum elevation value of each detection plane is less than the preset elevation difference threshold; obtaining a first point cloud elevation average value of the point cloud data within the first route pending detection plane and a first vector range of the first route pending detection plane.

[0010] Furthermore, the first vector range of the first route pending detection plane is mapped to the second route in the overlapping area of ​​the adjacent air strips to determine the second route pending detection plane in the second route, including: automatically mapping the first vector range to the second route to determine the second vector range of all detection planes in the second route; judging whether the second vector range exceeds the overlapping area of ​​the adjacent air strips; if the second vector range exceeds the overlapping area of ​​the adjacent air strips, determining that the current detection plane is a non-detection plane and then deleting it; if the second vector range does not exceed the overlapping area of ​​the adjacent air strips, obtaining the second maximum elevation value and the second minimum elevation value of each detection plane in the second route; judging the detection plane in the second route based on a preset elevation difference threshold; if the second elevation value difference between the second maximum elevation value and the second minimum elevation value of each detection plane is less than the preset elevation difference threshold, determining that the detection plane is the second route pending detection plane; obtaining the second point cloud elevation average value of the point cloud data in the second route pending detection plane.

[0011] Further, the step of obtaining the first point cloud elevation average of the first route effective detection plane and the second point cloud elevation average of the second route effective detection plane with the same name in all adjacent flight strips in the whole shooting area, and calculating the point cloud flight strip splicing elevation error value in the flight strip overlapping area based on the first point cloud elevation average and the second point cloud elevation average to determine the point cloud flight strip splicing elevation accuracy includes: calculating the point cloud flight strip splicing elevation error value according to the following formula:

[0012]

[0013] Among them, Z RMSE is the elevation error of the point cloud flight strip splicing, Z i is the average elevation of the first point cloud, Z i ' is the average elevation of the second point cloud, and n is the number of valid detected planes with the same name.

[0014] In a second aspect, an embodiment of the present invention provides a method for detecting the elevation accuracy of point cloud flight strip splicing, including: a pending detection plane acquisition module, used to perform a mobile search in the overlapping area of ​​adjacent flight strips through a preset detection plane, and acquire a first route pending detection plane and a second route pending detection plane in the overlapping area of ​​adjacent flight strips; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name of two adjacent routes; an effective detection plane acquisition module, used to determine whether the difference in the average point cloud elevation between the first route pending detection plane and the second route pending detection plane is within a preset value. If the value is within the threshold range of the average value elevation difference, if so, determine that the pending detection plane of the first route is the effective detection plane of the first route, and determine that the pending detection plane of the second route is the effective detection plane of the second route with the same name; a point cloud flight strip stitching elevation error value calculation module is used to obtain the first point cloud elevation average value of the first route effective detection plane and the second point cloud elevation average value of the second route effective detection plane with the same name in all adjacent flight strips overlapping areas in the entire shooting area, and calculate the point cloud flight strip stitching elevation error value in the flight strip overlapping area based on the first point cloud elevation average value and the second point cloud elevation average value, so as to determine the point cloud flight strip stitching elevation accuracy.

[0015] In a third aspect, an embodiment of the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program executable on the processor, and the processor implements the method described above when executing the computer program.

[0016] In a fourth aspect, an embodiment of the present invention provides a computer-readable medium having a non-volatile program code executable by a processor, wherein the program code enables the processor to execute the method as described above.

[0017] An embodiment of the present invention provides a method and device for detecting the elevation accuracy of point cloud flight strip stitching, including: performing a mobile search in an adjacent flight strip overlapping area through a preset detection plane to obtain a first route pending detection plane and a second route pending detection plane in the adjacent flight strip overlapping area; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name for two adjacent routes; determining whether the point cloud elevation average value difference between the first route pending detection plane and the second route pending detection plane is within a preset average value elevation difference threshold range, and if so, determining the first route pending detection plane as a first route valid detection plane, and determining the second route pending detection plane as a second route valid detection plane with the same name; obtaining a first point cloud elevation average value of the first route valid detection plane and a second point cloud elevation average value of the second route valid detection plane with the same name in all adjacent flight strip overlapping areas in the entire shooting area, and calculating the point cloud flight strip stitching elevation error value in the flight strip overlapping area based on the first point cloud elevation average value and the second point cloud elevation average value, so as to determine the point cloud flight strip stitching elevation accuracy. In this method, by searching and moving the detection plane in the entire shooting area and the overlapping area of ​​each flight strip and setting the point cloud elevation threshold, it is possible to automatically find the effective detection plane in the overlapping area of ​​adjacent flight strips, and calculate the elevation error by taking the average point cloud elevation of multiple pairs of effective detection planes in the entire shooting area, so as to quickly determine the effective detection plane for point cloud flight strip splicing, and then determine the elevation error value of point cloud flight strip splicing to determine the elevation accuracy of point cloud flight strip splicing. Compared with the prior art, the present application can automatically find the effective detection plane without other auxiliary data, and calculate the elevation error of point cloud flight strip splicing using multiple pairs of same-name effective detection planes in the overlapping area of ​​the flight strip, which alleviates the existing method of sampling detection, where although the overall error of point cloud flight strip splicing elevation is qualified, there are still many areas where the error exceeds the limit, and improves the calculation accuracy of the error of point cloud flight strip splicing elevation.

[0018] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A flow chart of a method for detecting elevation accuracy of point cloud flight strip splicing provided in the first embodiment of the present invention;

[0022] Figure 2 A flowchart of obtaining a pending detection plane with the same name provided in the first embodiment of the present invention;

[0023] Figure 3 A flow chart of a method for determining unreasonable elevation mutations provided in the first embodiment of the present invention;

[0024] Figure 4 A flow chart of another method for detecting elevation accuracy of point cloud flight strip splicing provided in the second embodiment of the present invention;

[0025] Figure 5 A schematic diagram of a detection plane and a moving step distance of the detection plane provided in the second embodiment of the present invention;

[0026] Figure 6 Schematic diagram of a device for detecting the elevation accuracy of point cloud flight strip splicing provided in Embodiment 3 of the present invention.

[0027] Icons: 1-Undetermined detection plane acquisition module; 2-Effective detection plane acquisition module; 3-Point cloud flight strip splicing elevation error value calculation module. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The raw data obtained by airborne laser radar is ranging data, which cannot be used directly. It needs to be preprocessed to generate a set of points that meet the requirements of the specification, called "point cloud". Preprocessing usually has two steps: one is point cloud data generation. That is, the POS data and laser ranging data are combined, the system calibration data is added, and the point cloud data is solved strip by strip to generate a single-strip three-dimensional point cloud. The second is point cloud strip stitching. The point cloud data of a shooting area is composed of several strips. There is data overlap between strips. Since the system positioning and attitude measurement between different strips will inevitably produce errors, the elevation of the same point solved by different routes in adjacent strips will be different. When the elevation difference exceeds the limit index value, it will make it difficult to stitch the point clouds of the two routes, and it will also directly affect the production of DSM (digital surface model) / DEM (Digital Elevation Model). Therefore, the elevation accuracy of point cloud strip stitching is a key factor affecting the quality of DSM / DEM, and it is particularly important to check the elevation accuracy of point cloud strip stitching.

[0030] In order to standardize the inspection behavior of the elevation accuracy of point cloud flight strips, the Technical Specifications for Airborne LiDAR Data Acquisition (CH 8024-2011) provides the index requirements for the elevation error of point cloud flight strips. When calculating the elevation error of point cloud flight strips in the shooting area, it is necessary to extract the elevation values ​​of the same-name points of two adjacent flight strips, and after calculating the mean error through the root mean square, it is used as the basis for the elevation accuracy of point cloud flight strips. Therefore, it is necessary to determine the same-name points between point cloud data flight strips first. However, the method of determining the same-name points between point cloud data flight strips is completely different from that of determining the same-name points between image data flight strips. Due to the influence of the sparseness of the point cloud, it is difficult to find the point cloud at the same position on adjacent flight strips, and it is impossible to directly calculate the elevation error of point cloud flight strips.

[0031] To this end, relevant scientific research institutes and point cloud data acquisition and processing companies have conducted relevant technical research. The main solution is to rely on detection planes to check the elevation error of point cloud flight strips, that is, to convert "points with the same name" into "surfaces with the same name". The specific method is: select a certain number of "same name" planes in the overlapping area of ​​adjacent flight strips, calculate the average point cloud elevation of the planes respectively, and calculate the elevation error of the point cloud flight strips through the root mean square of multiple pairs of planes as the basis for evaluating the accuracy of point cloud flight strips. Then, how to quickly and automatically select "same name" detection planes has become the first problem to be solved in the detection of elevation errors in point cloud flight strips.

[0032] At present, the elevation error of point cloud flight strip splicing is mainly calculated through field marking and indoor manual inspection.

[0033] The field marking method aims to calculate the elevation error of the point cloud flight strip splicing by laying out signboards in the overlapping areas of the flight strips and using the average elevation of the point cloud data on the two flight strip signboards. The general operation is as follows: before the aerial photography flight, according to the route planning and design results, set the precision verification area of ​​the flight strip splicing elevation error at the beginning, end, middle and other positions of the overlapping area between the flight strips; lay out a flat wooden board of the same material in each precision verification area, and the height difference between the four corners and the center of the board does not exceed 5mm; calculate the average elevation of the point cloud falling on each board, and use the difference between the average elevation of the point cloud on the two route boards of the adjacent flight strips to calculate the root mean square as the basis for determining the elevation accuracy of the flight strip splicing.

[0034] The advantage of this method is that the average elevation value of the points falling on the plate is directly counted as the elevation value of the point cloud data, without the need for interpolation calculation, and with high accuracy. At the same time, the average point cloud elevation on the sign board can be compared with the plate elevation value measured by the fourth-order leveling, which is conducive to detecting the absolute elevation accuracy of the point cloud data. The disadvantage is that the layout planning of the sign board needs to be considered in the aerial photography design stage, and the markers need to be made and laid out before the flight, which consumes a lot of manpower and material resources.

[0035] The manual inspection method in the office mainly involves manually selecting a suitable inspection plane in the overlapping area of ​​flight strips, counting the average elevation of the inspection plane point cloud, and calculating the elevation error of the point cloud flight strip splicing. The general operation is as follows: After the aerial photography flight, with the assistance of professional data such as digital line drawings, surface cover classification data or remote sensing images, find flat areas at the beginning, end, and middle of the overlapping area between flight strips as the accuracy verification area for the elevation error of the flight strip splicing; select flat feature objects (such as runways, roads, etc.) in the accuracy verification area, manually select the range, calculate the average point cloud elevation within the frame selection range of the two routes of the adjacent flight strips, and use the difference between the point cloud elevation averages to calculate the root mean square as the basis for determining the elevation accuracy of the flight strip splicing.

[0036] The advantage of this method is that the calculation can be completed without field work. The disadvantage is that it must rely on professional data such as images, and the process of finding flat features (such as runways, roads, etc.) is time-consuming. Even if a feature such as a road is found, if there is a slope, the calculation result may be inaccurate.

[0037] In addition, both the field marking method and the indoor manual inspection method are sampling inspections, and there is still a possibility that the elevation error of the point cloud splicing may exceed the limit in some parts.

[0038] To facilitate understanding of this embodiment, the embodiment of the present invention is described in detail below.

[0039] Embodiment 1:

[0040] Figure 1 This is a flow chart of a method for detecting elevation accuracy of point cloud flight strip splicing provided in Example 1 of the present invention.

[0041] Reference Figure 1 , the detection methods of point cloud flight strip splicing elevation accuracy include:

[0042] Step S101, performing a mobile search in the overlapping area of ​​adjacent air strips through a preset detection plane, obtaining a first route pending detection plane and a second route pending detection plane in the overlapping area of ​​adjacent air strips; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name of two adjacent routes.

[0043] Here, the above steps solve the problem of fast and automatic determination of detection planes with the same name in the overlapping areas of flight strips, that is, without relying on professional data such as digital line drawings, surface cover classification data or remote sensing images, it is possible to automatically and quickly find detection planes with the same name.

[0044] In one embodiment, reference Figure 2 , step S101 can also be implemented by the following steps:

[0045] Step S201, obtaining point cloud data in the overlapping area of ​​adjacent flight strips.

[0046] Step S202 , searching and moving in a first route in an overlapping area of ​​adjacent flight strips with a preset detection plane at a preset step distance to determine a first route pending detection plane in the first route, and obtaining a first vector range of the first route pending detection plane.

[0047] Here, the preset detection plane is a circular detection plane, and the preset step distance is consistent with the radius of the circular detection plane.

[0048] In one implementation, step S202 may also be implemented by the following steps:

[0049] Obtaining a first maximum elevation value and a first minimum elevation value of each detection plane within the first route;

[0050] Based on a preset elevation difference threshold, determining the detection plane within the first route;

[0051] If the first elevation value difference between the first maximum elevation value and the first minimum elevation value of each detection plane is less than a preset elevation difference threshold, the detection plane is determined to be a first route pending detection plane;

[0052] A first point cloud elevation average value of the point cloud data in a first route pending detection plane and a first vector range of the first route pending detection plane are obtained.

[0053] Step S203 , extending the first vector range of the first pending route detection plane to the second route in the overlapping area of ​​the adjacent flight strips to obtain a second pending route detection plane in the second route.

[0054] In one implementation, step S203 may also be implemented by the following steps:

[0055] The first vector range is automatically transferred to the second route, and the second vector range of all detection planes within the second route is determined;

[0056] Determine whether the second vector range exceeds the overlapping area of ​​adjacent flight strips;

[0057] If the second vector range exceeds the overlapping area of ​​adjacent flight strips, the current detection plane is determined to be a non-detection plane and then deleted;

[0058] If the second vector range does not exceed the overlapping area of ​​adjacent flight strips, obtaining a second maximum elevation value and a second minimum elevation value of each detection plane within the second flight route;

[0059] Based on a preset elevation difference threshold, determining the detection plane within the second route;

[0060] If the difference between the second maximum elevation value and the second minimum elevation value of each detection plane is less than a preset elevation difference threshold, the detection plane is determined to be the second route pending detection plane;

[0061] Obtain a second point cloud elevation average value of the point cloud data in the second route pending detection plane.

[0062] Step S102, determine whether the point cloud elevation average difference between the first route pending detection plane and the second route pending detection plane is within a preset average elevation difference threshold range. If so, determine the first route pending detection plane as a valid detection plane for the first route, and determine the second route pending detection plane as a valid detection plane with the same name for the second route.

[0063] Here, in order to ensure that the point cloud data in each detection plane is approximately a plane, it is necessary to preset an elevation difference threshold, which is 1 / 3 of the error in the point cloud elevation. The smaller the elevation difference, the closer the detection plane is to the horizontal plane.

[0064] Step S103, obtain the first point cloud elevation average value of the first route effective detection plane and the second point cloud elevation average value of the second route effective detection plane with the same name in all adjacent flight strips overlapping areas in the entire shooting area, and calculate the point cloud flight strip stitching elevation error value in the flight strip overlapping area based on the first point cloud elevation average value and the second point cloud elevation average value to determine the point cloud flight strip stitching elevation accuracy.

[0065] Here, the above steps detect the entire photographic area of ​​the plane and move the search in each flight strip overlapping area, and use multiple pairs of detection planes with the same name (large samples) in the flight strip overlapping area to evaluate the error in the point cloud flight strip stitching elevation. This avoids the situation where the error in the point cloud flight strip stitching elevation is generally qualified in the sampling detection, but there are still many areas where the error exceeds the limit, thereby improving the calculation accuracy of the error in the point cloud flight strip stitching elevation.

[0066] In one embodiment, step S203 calculates the point cloud flight path stitching elevation error value according to the following formula (1):

[0067]

[0068] Among them, Z RMSE is the elevation error of the point cloud flight strip splicing, Z i is the average elevation of the first point cloud, Z i ' is the average elevation of the second point cloud, and n is the number of valid detected planes with the same name.

[0069] Further, see Figure 3 , the detection method of point cloud flight strip splicing elevation accuracy also includes:

[0070] Step S301, determine whether the average point cloud elevation difference between the first pending route detection plane and the second pending route detection plane is within a preset average elevation difference threshold range. If not, there is a sudden change in point cloud elevation between the pending detection planes with the same name.

[0071] Here, if there is a large difference in the average elevation of a pair of point clouds in the same pending detection plane, they can be automatically identified.

[0072] Step S302, obtaining the vector range of the pending detection plane with the same name, and determining whether the elevation mutation of the point cloud is an unreasonable elevation mutation based on the image or auxiliary data.

[0073] Here, if the error in the elevation of the point cloud flight strip splicing in a certain shooting area is acceptable, but the time span of point cloud data acquisition in different routes of adjacent flight strips at the same location in the local area is large, and the growth of ground objects and vegetation changes due to the season, resulting in large differences in the elevation values ​​of the same point cloud data, it means that there is an unreasonable elevation mutation in the shooting area. If this error cannot be detected and this problem is covered up and carried to the next process, it will directly affect the production quality of DEM / DSM.

[0074] With the help of images or other auxiliary data, through manual interpretation, the reasons for the sudden change in point cloud elevation are analyzed to determine whether the pending detection plane with the same name is an unreasonable elevation change.

[0075] Step S303, if the elevation mutation of the point cloud is an unreasonable elevation mutation, a problem area is formed based on all pending detection planes with the same name where unreasonable elevation mutations occur, so as to re-solve the point cloud data of the adjacent flight strips where the pending detection planes with the same name are located or enable the airborne laser radar to re-acquire the point cloud data.

[0076] Here, if it is an unreasonable point cloud elevation mutation range, such detection planes are merged to form a problem area, and such vector ranges can be output and merged to provide a reference range for re-solving the flight strip point cloud data or performing supplementary flight / re-fly.

[0077] An embodiment of the present invention provides a method for detecting the elevation accuracy of point cloud flight strip stitching, comprising: performing a mobile search in an adjacent flight strip overlapping area through a preset detection plane to obtain a first route pending detection plane and a second route pending detection plane in the adjacent flight strip overlapping area; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name of two adjacent routes; determining whether the point cloud elevation average value difference between the first route pending detection plane and the second route pending detection plane is within a preset average value elevation difference threshold range, and if so, determining the first route pending detection plane as a first route valid detection plane, and determining the second route pending detection plane as a second route valid detection plane with the same name; obtaining a first point cloud elevation average value of the first route valid detection plane and a second point cloud elevation average value of the second route valid detection plane with the same name in all adjacent flight strip overlapping areas in the entire shooting area, and calculating the point cloud flight strip stitching elevation error value in the flight strip overlapping area based on the first point cloud elevation average value and the second point cloud elevation average value, so as to determine the point cloud flight strip stitching elevation accuracy. This method can automatically find the effective detection plane in the overlapping area of ​​adjacent flight strips by searching and moving the detection plane in the whole shooting area and the overlapping area of ​​each flight strip and setting the point cloud elevation threshold, and calculate the elevation error by the average point cloud elevation of multiple pairs of effective detection planes in the whole shooting area, so as to quickly determine the effective detection plane for point cloud flight strip splicing, and then determine the elevation error value of point cloud flight strip splicing to determine the elevation accuracy of point cloud flight strip splicing. Compared with the existing technology, this method automatically finds the same-name effective detection plane by searching and moving the circular detection plane; by calculating the root mean square of the point cloud elevation average of a large sample of the same-name effective detection planes, the elevation accuracy of point cloud flight strip splicing can be quickly checked, thereby improving the inspection efficiency; in addition, this method can also effectively detect the sudden change of point cloud elevation at the same location on adjacent flight routes, thereby improving the overall accuracy of point cloud data.

[0078] Embodiment 2:

[0079] Figure 4 A flow chart of another method for detecting elevation accuracy of point cloud flight strip splicing provided in Embodiment 2 of the present invention.

[0080] The point cloud data acquisition technology design is carried out according to the accuracy requirements of point cloud data processing results, the reflection of objects and topographic conditions in the shooting area, the performance of the aerial camera used, etc. The aerial photography flight obtains the original scanning data and POS data of the airborne laser radar, and generates the point cloud data of each flight strip after preprocessing, and extracts the vector range of the flight strip overlapping area based on the flight strip point cloud data. Based on this:

[0081] Preset the radius of the circular detection plane and the moving step of the detection plane.

[0082] Here, in order to facilitate the search in the overlapping area of ​​the flight strip, a circular detection plane is designed. The moving step of the detection plane is consistent with the radius of the circle. Figure 5 Schematic diagram of the detection plane and the moving step of the detection plane, where r is the radius of the circular detection plane. The radius of the circular detection plane is determined according to the size of the point cloud spacing and the actual situation of the characteristic objects, as shown in Table 1. For example, the width of a flat runway, highway, etc. is about 10 meters. Combined with the size of the point cloud spacing, the radius of the circular detection plane can generally be set to twice the point cloud spacing, which is roughly equivalent to the DEM grid spacing, to ensure that the number of point clouds in each detection plane is not less than 10. It can also be adjusted according to the size of the point cloud spacing, the actual situation of the characteristic objects, etc.

[0083] Table 1 Detection plane radius and moving step value

[0084]

[0085] The detection plane searches and moves within the first route in the overlapping area of ​​adjacent flight strips, counts the first maximum elevation value and the first minimum elevation value of each detection plane within the first route, and calculates the first elevation value difference according to the first maximum elevation value and the first minimum elevation value.

[0086] Set the elevation difference threshold M in the detection plane, and determine whether the first elevation value difference exceeds the elevation difference threshold. If the first elevation value difference in the detection plane is within the range of M, the detection plane is regarded as the first route pending detection plane A, and the first point cloud elevation average of the point cloud data in the detection plane A is counted, and the first vector range in the detection plane A is recorded at the same time.

[0087] Here, in order to ensure that the point cloud data in each detection plane is approximately flat, it is necessary to set the thresholds of the maximum and minimum elevation differences of the point cloud in the detection plane. The smaller the elevation difference, the closer the detection plane is to the horizontal plane. The threshold can generally be set to 1 / 3 of the error in the point cloud elevation. The elevation difference thresholds in the detection plane are shown in Table 2.

[0088] Table 2 Detection plane elevation difference threshold

[0089] Drawing scale Terrain Type Point cloud elevation error (m) Point cloud maximum and minimum elevation difference threshold (m) 1:500 Flatland 0.15 0.05 1:1000 Flatland 0.15 0.05 1:2000 Flatland 0.25 0.08 1:5000 Flatland 0.35 0.12 1:10000 Flatland 0.35 0.12

[0090] The center coordinates of the circle in the detection plane A are automatically transferred to the second route of the adjacent flight strip, and the second vector range B is formed according to the radius of the circle. The second vector range B is checked for fit with the flight strip overlap area to determine whether B exceeds the flight strip overlap area. If so, it is considered as a non-detection plane and deleted.

[0091] The second maximum elevation value and the second minimum elevation value of the point cloud data in B are counted, and it is determined whether the maximum and minimum elevation difference of the point cloud data in B exceeds M. If it does not exceed M, B is regarded as the second route pending detection plane A' of the adjacent flight strip, and the second point cloud elevation average value of the point cloud data in A' is counted.

[0092] Set the average elevation difference threshold between A and A'. The threshold can be set according to 2 / 3 of the error in the point cloud elevation, and can also be adjusted according to the type of ground feature, etc.

[0093] If the difference between the average values ​​of the elevations of A and A' does not exceed the average value elevation difference threshold, A is determined to be a valid detection plane for the first route, and A' is determined to be a valid detection plane with the same name for the second route.

[0094] If the difference between the average values ​​of A and A' elevation exceeds the average elevation difference threshold, the vector range of the detection plane is output, and the cause of the point cloud elevation mutation is analyzed with the help of images or other auxiliary data to determine whether it is an unreasonable elevation mutation. If it is an unreasonable point cloud elevation mutation range, such detection planes are merged to form a problem area, providing a reference range for re-calculating the flight strip point cloud data or performing supplementary flight / re-flying.

[0095] The first point cloud elevation average of A and the second point cloud elevation average of A' in the overlapping area of ​​all adjacent flight strips in the entire shooting area are obtained, and based on the first point cloud elevation average and the second point cloud elevation average, the point cloud flight strip stitching elevation error value in the overlapping area of ​​the flight strip is calculated according to the above formula (1).

[0096] An embodiment of the present invention provides a method for detecting the elevation accuracy of point cloud flight strip stitching, comprising: performing a mobile search in an adjacent flight strip overlapping area through a preset detection plane to obtain a first route pending detection plane and a second route pending detection plane in the adjacent flight strip overlapping area; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name of two adjacent routes; determining whether the point cloud elevation average value difference between the first route pending detection plane and the second route pending detection plane is within a preset average value elevation difference threshold range, and if so, determining the first route pending detection plane as a first route valid detection plane, and determining the second route pending detection plane as a second route valid detection plane with the same name; obtaining a first point cloud elevation average value of the first route valid detection plane and a second point cloud elevation average value of the second route valid detection plane with the same name in all adjacent flight strip overlapping areas in the entire shooting area, and calculating the point cloud flight strip stitching elevation error value in the flight strip overlapping area based on the first point cloud elevation average value and the second point cloud elevation average value, so as to determine the point cloud flight strip stitching elevation accuracy. This method automatically detects the elevation mutation of point cloud data at the same location in adjacent flight strips by setting the average elevation difference threshold of the first route pending detection plane A and the second route pending detection plane A' of different routes in adjacent flight strips, and analyzes the cause of the elevation mutation of the point cloud with the help of image or other auxiliary data to determine whether it is an unreasonable elevation mutation. If it is an unreasonable point cloud elevation mutation range, such detection planes are merged to form a problem area, providing a reference range for re-calculating the point cloud data of the flight strip or performing supplementary flight / re-flying.

[0097] Embodiment three:

[0098] Figure 6 Schematic diagram of a device for detecting the elevation accuracy of point cloud flight strip splicing provided in Embodiment 3 of the present invention.

[0099] Reference Figure 6 , the detection device for the elevation accuracy of point cloud flight strip splicing includes:

[0100] The pending detection plane acquisition module 1 is used to perform a mobile search in the overlapping area of ​​adjacent flight strips through a preset detection plane, and acquire the first route pending detection plane and the second route pending detection plane in the overlapping area of ​​adjacent flight strips; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name of two adjacent routes;

[0101] The effective detection plane acquisition module 2 is used to determine whether the point cloud elevation average difference between the first route pending detection plane and the second route pending detection plane is within a preset average elevation difference threshold range, and if so, determine the first route pending detection plane as the first route effective detection plane, and determine the second route pending detection plane as the second route effective detection plane with the same name;

[0102] The point cloud flight strip stitching elevation error value calculation module 3 is used to obtain the first point cloud elevation average value of the first route effective detection plane in the overlapping area of ​​all adjacent flight strips in the entire shooting area and the second point cloud elevation average value of the second route effective detection plane with the same name, and calculate the point cloud flight strip stitching elevation error value in the flight strip overlapping area based on the first point cloud elevation average value and the second point cloud elevation average value to determine the point cloud flight strip stitching elevation accuracy.

[0103] An embodiment of the present invention provides a device for detecting the elevation accuracy of point cloud flight strip stitching, comprising: performing a mobile search in an adjacent flight strip overlapping area through a preset detection plane, and obtaining a first route pending detection plane and a second route pending detection plane in the adjacent flight strip overlapping area; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name of two adjacent routes; judging whether the point cloud elevation average value difference between the first route pending detection plane and the second route pending detection plane is within a preset average value elevation difference threshold range, and if so, determining the first route pending detection plane as a first route effective detection plane, and determining the second route pending detection plane as a second route effective detection plane with the same name; obtaining a first point cloud elevation average value of the first route effective detection plane and a second point cloud elevation average value of the second route effective detection plane with the same name in all adjacent flight strip overlapping areas in the entire shooting area, and calculating the point cloud flight strip stitching elevation error value in the flight strip overlapping area based on the first point cloud elevation average value and the second point cloud elevation average value, so as to determine the point cloud flight strip stitching elevation accuracy. This method can automatically find the effective detection plane in the overlapping area of ​​adjacent flight strips by searching and moving the detection plane in the whole shooting area and the overlapping area of ​​each flight strip and setting the point cloud elevation threshold, and calculate the elevation error by taking the average point cloud elevation of multiple pairs of effective detection planes in the whole shooting area, so as to quickly determine the effective detection plane for point cloud flight strip splicing, and then determine the elevation error value of point cloud flight strip splicing to determine the elevation accuracy of point cloud flight strip splicing. Compared with the prior art, this application can automatically find the effective detection plane without other auxiliary data, and calculate the elevation error of point cloud flight strip splicing using multiple pairs of detection planes with the same name in the overlapping area of ​​the flight strip, avoiding the situation that the error of point cloud flight strip splicing elevation is qualified as a whole in the sampling detection, but there are still many areas where the error exceeds the limit, and improving the calculation accuracy of the error of point cloud flight strip splicing elevation.

[0104] An embodiment of the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for detecting the elevation accuracy of point cloud flight strip splicing provided in the above embodiment are implemented.

[0105] An embodiment of the present invention also provides a computer-readable medium having a non-volatile program code executable by a processor, wherein a computer program is stored on the computer-readable medium, and when the computer program is executed by the processor, the steps of the method for detecting the elevation accuracy of point cloud flight strip splicing of the above embodiment are executed.

[0106] The computer program product provided in the embodiment of the present invention includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the method described in the previous method embodiment. The specific implementation can be found in the method embodiment and will not be repeated here.

[0107] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0108] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0109] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0110] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0111] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for detecting the elevation accuracy of point cloud flight strip splicing, characterized in that: include: By performing a mobile search in the overlapping area of ​​adjacent flight strips through a preset detection plane, a first route pending detection plane and a second route pending detection plane in the overlapping area of ​​adjacent flight strips are obtained; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name of two adjacent routes; Determine whether the point cloud elevation average difference between the first pending route detection plane and the second pending route detection plane is within a preset average elevation difference threshold range; if so, determine the first pending route detection plane as a first route valid detection plane, and determine the second pending route detection plane as a second route valid detection plane with the same name; The first point cloud average elevation value of the first route valid detection plane in all the adjacent flight strips overlapping areas in the entire shooting area and the second point cloud average elevation value of the second route valid detection plane with the same name are obtained, and based on the first point cloud average elevation value and the second point cloud average elevation value, the point cloud flight strip stitching elevation error value in the flight strip overlapping area is calculated to determine the point cloud flight strip stitching elevation accuracy.

2. The detection method according to claim 1, characterized in that: The method further comprises: Determine whether the average value difference of the point cloud elevation between the first route pending detection plane and the second route pending detection plane with the same name is within the preset average value elevation difference threshold range; if not, there is a sudden change in the point cloud elevation of the pending detection plane with the same name; Obtaining the vector range of the pending detection plane with the same name, and determining whether the elevation mutation of the point cloud is an unreasonable elevation mutation based on images or auxiliary data; If the point cloud elevation mutation is the unreasonable elevation mutation, a problem area is formed based on all the pending detection planes with the same name where the unreasonable elevation mutation occurs, so as to re-solve the point cloud data of the adjacent flight strips where the pending detection planes with the same name are located or enable the airborne laser radar to re-acquire the point cloud data.

3. The detection method according to claim 1, characterized in that: The step of performing a mobile search in the overlapping area of ​​adjacent flight strips by using a preset detection plane to obtain a first route pending detection plane and a second route pending detection plane in the overlapping area of ​​adjacent flight strips; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name of the two adjacent routes, comprises: Acquire point cloud data within the overlapping area of ​​the adjacent flight strips; Searching and moving the preset detection plane in a first route in an overlapping area of ​​adjacent flight strips with a preset step distance to determine a first route pending detection plane in the first route, and obtaining a first vector range of the first route pending detection plane; The first vector range of the first route pending detection plane is extended to the second route within the overlapping area of ​​the adjacent flight strips to obtain the second route pending detection plane within the second route.

4. The detection method according to claim 3, characterized in that: The preset detection plane is a circular detection plane, and the preset step distance is consistent with the radius of the circular detection plane.

5. The detection method according to claim 3, characterized in that: The step of searching and moving the preset detection plane in a first route in an overlapping area of ​​adjacent flight strips with a preset step distance to determine a first route pending detection plane in the first route, and obtaining a first vector range of the first route pending detection plane includes: Acquire a first maximum elevation value and a first minimum elevation value of each of the detection planes within the first route; Based on the preset elevation difference threshold, judging the detection plane within the first route; If the first elevation value difference between the first maximum elevation value and the first minimum elevation value of each of the detection planes is less than the preset elevation difference threshold, determining the detection plane as the first route pending detection plane; A first point cloud elevation average value of the point cloud data in the first route pending detection plane and a first vector range of the first route pending detection plane are obtained.

6. The detection method according to claim 3, characterized in that: The step of extending the first vector range of the first pending route detection plane to the second route in the overlapping area of ​​the adjacent flight strips to determine the second pending route detection plane in the second route includes: Automatically transfer the first vector range to the second route, and determine the second vector range of all the detection planes within the second route; Determining whether the second vector range exceeds the overlapping area of ​​the adjacent flight strips; If the second vector range exceeds the adjacent flight strip overlap area, determining that the current detection plane is a non-detection plane and then deleting it; If the second vector range does not exceed the overlapping area of ​​the adjacent flight strips, obtaining a second maximum elevation value and a second minimum elevation value of each of the detection planes within the second flight route; Based on the preset elevation difference threshold, determining the detection plane within the second route; If the second elevation value difference between the second maximum elevation value and the second minimum elevation value of each of the detection planes is less than the preset elevation difference threshold, determining the detection plane as the second route pending detection plane; Obtain a second point cloud elevation average value of the point cloud data in the second route pending detection plane.

7. The detection method according to claim 1, characterized in that: The step of obtaining the first point cloud elevation average of the first route effective detection plane and the second point cloud elevation average of the second route effective detection plane with the same name in all the adjacent flight strips overlapping areas in the full shooting area, and calculating the point cloud flight strip stitching elevation error value in the flight strip overlapping area based on the first point cloud elevation average and the second point cloud elevation average to determine the point cloud flight strip stitching elevation accuracy includes: The elevation error of the point cloud flight strip splicing is calculated according to the following formula: in, is the elevation error value of the point cloud flight strip stitching, is the average elevation of the first point cloud, is the average elevation of the second point cloud, and n is the number of valid detected planes with the same name.

8. A device for detecting the elevation accuracy of point cloud flight strip splicing, characterized in that: include: A pending detection plane acquisition module is used to perform a mobile search in the overlapping area of ​​adjacent flight strips through a preset detection plane, and acquire a first route pending detection plane and a second route pending detection plane in the overlapping area of ​​adjacent flight strips; wherein the first route pending detection plane and the second route pending detection plane are pending detection planes with the same name of two adjacent routes; an effective detection plane acquisition module, used to determine whether the point cloud elevation average difference between the first pending route detection plane and the second pending route detection plane is within a preset average elevation difference threshold range, and if so, determine the first pending route detection plane as a first route effective detection plane, and determine the second pending route detection plane as a second route effective detection plane with the same name; The point cloud flight strip stitching elevation error value calculation module is used to obtain the first point cloud elevation average value of the first route effective detection plane in the overlapping area of ​​all adjacent flight strips in the entire shooting area and the second point cloud elevation average value of the second route effective detection plane with the same name, and calculate the point cloud flight strip stitching elevation error value in the overlapping area of ​​the flight strip based on the first point cloud elevation average value and the second point cloud elevation average value to determine the point cloud flight strip stitching elevation accuracy.

9. An electronic system, characterized in that: The electronic system includes: a processing device and a storage device; The storage device stores a computer program, which, when executed by the processing device, executes the method for detecting the elevation accuracy of point cloud flight strip splicing according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processing device, the steps of the method for detecting the elevation accuracy of point cloud flight strip splicing as described in any one of claims 1 to 7 are executed.

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