CN113776504B - High-precision photographing and quality control method for water engineering unmanned aerial vehicle with complex structure - Google Patents
High-precision photographing and quality control method for water engineering unmanned aerial vehicle with complex structure Download PDFInfo
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Abstract
The invention discloses a high-precision photographing and quality control method for a water engineering unmanned aerial vehicle with a complex structure. It comprises the following steps: step 1: shooting by an unmanned aerial vehicle at four points; step 2: extracting the geographic coordinates of four corner points from the EXIF information of the four images obtained in the step 1; and step 3: calculating the attitude of the construction surface and planning a flight path based on the construction surface; and 4, step 4: automatic shooting by an unmanned aerial vehicle; and 5: aerial triangulation processing and aerial triangulation result intelligent analysis; step 6: complementary shooting flight path planning based on the analysis of the overlapping degree of the connecting points; and 7: automatic supplementary shooting by the unmanned aerial vehicle; and 8: and (4) carrying out precise geometric positioning and precise dense matching according to the high-resolution images obtained in the step (4) and the step (7) to obtain a precise and high-precision water engineering geographic information product. The invention has the advantages of fast obtaining high-resolution images and automatically controlling the quality.
Description
Technical Field
The invention relates to the field of water engineering data acquisition, in particular to a high-precision photographing and quality control method for a water engineering unmanned aerial vehicle with a complex structure;
the water engineering which can be fitted by one surface is simple-structure water engineering, such as regular dams along the shore and the like; the complex structure water engineering refers to water engineering which needs a plurality of surfaces to be completely fitted, such as large hydropower stations and the like.
Background
Water engineering is an important engineering facility for regulating and controlling the time-space distribution of water resources and optimizing the allocation of the water resources. China is one of the most huge countries of the world in water works construction scale, and water works are spread all over the country, thereby playing great benefits in flood control, irrigation, power generation, water supply and other aspects; however, most of water projects are built in complex hydrogeology and engineering geological environments, and are influenced by river impact and temperature load in the actual operation process, and some water projects are more likely to be subjected to strong impact of earthquakes to deform. Most of water projects in China are built decades ago, and due to the fact that the flood control standard is low and the construction quality is poor, ageing and deformation of different degrees exist after decades of use; once the engineering deformation exceeds the allowable limit, the risk of cracks, leakage and dam break can be caused; therefore, the high-precision and fine spatial data acquisition is carried out on the water project, and the method is in accordance with the important requirements of the national civilization;
in order to obtain a high-resolution and high-quality image of a scene target, the existing method generally adopts oblique photogrammetry or close-range photogrammetry to acquire data; oblique photogrammetry usually uses a multi-lens camera to shoot data, and a multi-view image of a target scene can be obtained by one-time exposure, so that the data acquisition efficiency of the large-range target scene is high; however, the oblique photogrammetry is carried out from top to bottom, and the photographic angle is fixed, so that the oblique photogrammetry cannot adapt to the complex structure of the water project, and the problems of loss and more serious deformation of textures in an oblique image are caused when the oblique photogrammetry is close to the bottom of the water project;
the close-range photogrammetry is ground photogrammetry with a photographic distance within 100 meters, although the theory and the method thereof are greatly developed in recent years, the problems of small photographic flexibility, low efficiency and high cost caused by the fact that a frequently moving photographing base station is required and even a scaffold is built to complete photographing still exist in engineering application;
both of the two existing methods have deficiencies; in addition, in the shooting process, some complicated regions (such as large space fluctuation, complex structure and the like) exist, and a situation that a fine and complete modeling effect cannot be obtained in one-time shooting may exist; from the viewpoint of quality control, the supplement flight is required; however, in the existing flying compensation mode, an operator manually operates the unmanned aerial vehicle to shoot one flying compensation area, so that the efficiency is low, and the requirement on the operator is high;
therefore, it is necessary to develop a high-precision photographing and quality control method for a water engineering unmanned aerial vehicle with a complex structure.
Disclosure of Invention
The invention aims to provide a high-precision photographing and quality control method for a water engineering unmanned aerial vehicle with a complex structure, which can acquire a high-resolution image and automatically perform quality control (namely automatic flying compensation), ensures the fineness and the integrity of a modeling effect, can automatically operate, is simple and convenient to operate and has very high overall efficiency.
In order to achieve the purpose, the technical scheme of the invention is as follows: a high-precision shooting and quality control method for a water engineering unmanned aerial vehicle with a complex structure is characterized by comprising the following steps: comprises the following steps of (a) carrying out,
step 1: shooting by an unmanned aerial vehicle at four points;
operating a rotor unmanned aerial vehicle with RTK (carrier phase differential technology), and respectively carrying out conventional shooting at four angular points in a water engineering range to obtain four angular point images with high-precision positioning coordinates;
step 2: extracting geographic coordinates (including longitude, latitude, elevation and the like) of four corner points from the EXIF information of the four images obtained in the step 1; EXIF information is an abbreviation of exchangeable image files, is specially set for photos of a digital camera, and can record attribute information and shooting data of the digital photos;
and step 3: calculating the attitude of the construction surface and planning a flight path based on the construction surface;
according to the geographical coordinates of the four angular points of the water project obtained in the step (2), fitting the water project target by using a space construction surface to obtain a fitted construction surface, and then automatically calculating according to the normal vector angle of the surface and the set shooting parameters (such as shooting distance, overlapping degree and the like) to obtain the shooting attitude of the unmanned aerial vehicle and the three-dimensional track of the rotor unmanned aerial vehicle;
and 4, step 4: automatic shooting by an unmanned aerial vehicle;
importing the three-dimensional flight path information obtained in the step (3) into a flight control system of the unmanned aerial vehicle, taking off the unmanned aerial vehicle, and automatically carrying out veneering photography according to the imported three-dimensional flight path information to obtain a high-resolution water engineering target image;
and 5: aerial triangulation processing and aerial triangulation result intelligent analysis;
and (3) aerial triangulation processing: performing aerial triangulation processing according to the high-resolution water engineering target image obtained in the step 4 to obtain an initial point cloud;
the aerial triangulation result intelligent analysis comprises a complementary shooting flight path planning based on sparse point analysis and a complementary shooting flight path planning based on connection point overlapping degree analysis;
complementary shooting flight path planning based on sparse point analysis: automatically analyzing the initial point cloud, and checking whether an area with few abnormal points exists;
if the unmanned aerial vehicle three-dimensional flight path exists, the area is taken out, and a structural surface is automatically fitted and the three-dimensional flight path of the unmanned aerial vehicle is calculated;
if not, jumping to step 6;
step 6: complementary shooting flight path planning based on the analysis of the overlapping degree of the connecting points;
calculating the overlapping degree of each connecting point according to the aerial triangulation result obtained in the step 5; automatically analyzing the overlapping degrees of all the connecting points, and checking whether an area with abnormally small overlapping degree exists;
if the unmanned aerial vehicle three-dimensional flight path exists, the area is taken out, and a structural surface is automatically fitted and the three-dimensional flight path of the unmanned aerial vehicle is calculated; skipping to step 7;
if not, jumping to step 8;
and 7: automatic supplementary shooting by the unmanned aerial vehicle;
importing the three-dimensional flight path information obtained in the step 5 and the step 6 into a flight control system of the unmanned aerial vehicle, automatically performing secondary flight path planning on the area needing to be compensated and shooting to obtain a high-resolution image corresponding to the compensated flight;
and 8: and (4) carrying out precise geometric positioning and precise dense matching according to the high-resolution images obtained in the step (4) and the step (7) to obtain a precise and high-precision water engineering geographic information product.
In the technical scheme, the direction and the range of the fitted structural surface are determined according to the geographic coordinates obtained by the four corners corresponding to the four images shot by the unmanned aerial vehicle in the water project target range in the step 1.
In the above technical solution, in step 5, the automatic analysis of the booming area is performed according to the initial point cloud obtained by aerial triangulation, and the specific method is as follows:
dividing a fitting structural surface into regular grids, projecting all points of the initial point cloud onto an equivalent fitting structural surface, and then counting the number of points in each grid in the grids;
the grid distance is determined according to the shooting distance, the focal length, the image width and the pixel size:
wherein
Respectively are equivalent fitting structural surfaces
The pitch of the grid in the direction is,
which is the distance of the photograph to be taken,
is the focal length of the lens, and is,
is the width of the image, and is,
is the pixel size of the image;
the formula for projecting the point cloud onto the fitted structured surface is:
wherein
In order to fit the parameters of the construction surface equivalently,
as the coordinates of each point in the point cloud,
the coordinates after projection are obtained;
taking the maximum value P of the points of all gridsmaxThe threshold value is set to 1/3PmaxIf the number of the points is less than the threshold value, the grid is the area to be compensated;
fitting a structural surface by using points in the grid and automatically calculating a three-dimensional flight path of the area to be compensated;
the foregoing indicates the multiplication number.
In the above technical solution, in step 6, the automatic analysis of the booming area is performed according to the overlapping degrees of all the connection points obtained by the aerial triangulation, and the specific method is as follows:
according to the method in the step 5, dividing the fitting construction surface into regular grids, then projecting all the connection points to the equivalent fitting construction surface, and then counting the average overlapping degree of the connection points in each grid;
taking the value with the maximum average overlapping degree in all grids as OmaxThe threshold value is set to 1/3OmaxAnd the grid with the average overlapping degree value smaller than the threshold value is the area to be compensated.
Compared with the prior art, the invention has the following advantages:
1) the invention can obtain high-resolution images (the image resolution is millimeter level) and carry out high-precision three-dimensional reconstruction, and the method has the advantages of automatic operation, simple and convenient operation and very high overall efficiency (the unmanned aerial vehicle automatically shoots according to air routes and does not need people to carry out a large amount of operations in the shooting process); in addition, the invention carries out the flight path planning by shooting four corner points, does not need to prepare initial terrain information in advance or carry out coarse flight modeling, has higher efficiency, reduces the operation time and has more flexible mode; the three-dimensional track is shot over the surface of the water project, so that the problems of texture compression and geometric deformation are avoided;
2) according to the method, the area needing to be compensated is obtained through automatic analysis and calculation by utilizing the sparse distribution of the initial point cloud obtained through aerial triangulation of the shot images and the overlapping degree of all the connecting points, and the corresponding three-dimensional flight path is automatically generated for compensation, so that the flight quality and the operation efficiency are more comprehensively ensured, the problem of rework of the aviation industry is avoided, and the high-resolution images can be quickly obtained and the quality control (namely automatic compensation) is automatically carried out;
according to the invention, by fitting the structural surface of the water project, the unmanned aerial vehicle shoots perpendicular to the structural surface, and does not shoot from top to bottom, so that the bottom of the water project can be shot accurately and clearly;
when the unmanned aerial vehicle is used for shooting, the shooting distance is generally less than 30 meters, and the effect of close-range photogrammetry can be achieved or even exceeded.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a schematic diagram of four-point shooting of a water project target in an embodiment of the present invention;
FIG. 3 is a three-dimensional track chart of a unmanned aerial vehicle and a camera pose of a human machine in an embodiment of the invention;
FIG. 4 is a to-be-compensated-shot area diagram detected from the initial point cloud after aerial triangulation in the embodiment of the present invention;
FIG. 5 is a diagram of a region to be subjected to complementary shooting detected by the connection point overlapping degree after aerial triangulation in the embodiment of the present invention;
FIG. 6 is a three-dimensional track map of an area to be subjected to complementary shooting, which is automatically generated according to an embodiment of the present invention;
FIG. 7 is a result diagram of three-dimensional modeling of a region that needs to be compensated for flying when a control group does not perform compensation flying in the embodiment of the present invention;
fig. 8 is a result diagram of three-dimensional modeling of a region that needs to be subjected to compensation flight when an experimental group performs compensation flight in the embodiment of the present invention.
Detailed Description
The embodiments of the present invention will be described in detail with reference to the accompanying drawings, which are not intended to limit the present invention, but are merely exemplary. While the advantages of the invention will be clear and readily understood by the description.
With reference to the accompanying drawings: a high-precision shooting and quality control method for a water engineering unmanned aerial vehicle with a complex structure comprises the following steps:
step 1: shooting by an unmanned aerial vehicle at four points;
operating a rotor unmanned aerial vehicle with RTK, and respectively carrying out conventional shooting at four angular points in a water engineering range to obtain four angular point images with high-precision positioning coordinates; the invention uses the geographic coordinates of the four angular point images in the step 1 to fit a space structure surface;
step 2: extracting geographic coordinates (including longitude, latitude, elevation and other geographic coordinates) of four corner points from the EXIF information of the four images obtained in the step 1;
and step 3: calculating the attitude of the construction surface and planning a flight path based on the construction surface;
performing structural surface fitting on the water project target according to the geographical coordinates of the four angular points of the water project obtained in the step 2 to obtain a fitted surface, and automatically calculating according to the normal vector angle of the surface and the set shooting parameters (shooting distance, overlapping degree and the like) to obtain the shooting attitude of the unmanned aerial vehicle and the three-dimensional track of the rotor unmanned aerial vehicle; according to the invention, the structural surface is rapidly obtained according to four angular points shot by the unmanned aerial vehicle, and the initial terrain information is not needed;
and 4, step 4: automatic shooting by an unmanned aerial vehicle;
importing the three-dimensional flight path information obtained in the step 3 into a flight control system of the unmanned aerial vehicle, taking off the unmanned aerial vehicle, and automatically carrying out veneering photography according to the three-dimensional flight path information imported in the step 3 to obtain a high-resolution water project target image;
and 5: aerial triangulation processing and aerial triangulation result intelligent analysis;
and (3) aerial triangulation processing: performing aerial triangulation processing according to the high-resolution water engineering target image obtained in the step 4 to obtain an initial point cloud;
the aerial triangulation result intelligent analysis comprises a complementary shooting flight path planning based on sparse point analysis and a complementary shooting flight path planning based on connection point overlapping degree analysis;
complementary shooting flight path planning based on sparse point analysis: automatically analyzing the initial point cloud, and checking whether an area with few abnormal points exists; if the unmanned aerial vehicle three-dimensional flight path exists, taking out the area (the area with few point anomalies), automatically fitting a space construction surface and calculating the three-dimensional flight path of the unmanned aerial vehicle; if not, jumping to step 6;
step 6: complementary shooting flight path planning based on the analysis of the overlapping degree of the connecting points;
calculating the overlapping degree of each connecting point according to the aerial triangulation result obtained in the step 5; automatically analyzing the overlapping degrees of all the connecting points, and checking whether an area with abnormally small overlapping degree exists;
if the area exists, taking out the area (the area with the abnormally small overlapping degree), automatically fitting a structural surface and calculating the unmanned aerial vehicle fly-by three-dimensional flight path; skipping to step 7;
if not, jumping to step 8;
and 7: automatic supplementary shooting by the unmanned aerial vehicle;
importing the three-dimensional flight path information obtained in the step 5 and the step 6 into a flight control system of the unmanned aerial vehicle, automatically performing secondary flight path planning and shooting on the area needing flying compensation, and obtaining a corresponding high-resolution water engineering target image for flying compensation;
and 8: and (4) performing accurate geometric positioning and fine dense matching according to the high-resolution water project target images obtained in the steps (4) and (7) to obtain a fine high-precision water project geographic information product (as shown in figure 1).
In the step 1, determining the direction and the range of a fitted structural surface according to geographic coordinates obtained by four corner points corresponding to four images of an unmanned aerial vehicle in a water project target range, and determining a shot surface and range without initial geographic information data or performing data processing after coarse flight of the unmanned aerial vehicle to obtain initial three-dimensional initial topographic information; initial geographic information data are not needed, the unmanned aerial vehicle does not need to fly roughly in a large range and perform data processing to obtain initial three-dimensional initial terrain information, the shot surface and range can be determined, and therefore operation efficiency is greatly improved.
And step 3, calculating according to the angle of the slope to obtain the shooting attitude of the unmanned aerial vehicle and the three-dimensional track of the rotor unmanned aerial vehicle.
For areas which are possibly complex or have large fluctuation of a water engineering target, if global shooting is carried out only once, the effect of final modeling is deficient, from the perspective of global quality control of three-dimensional reconstruction, close-distance supplementary shooting needs to be carried out on the areas, and the supplementary shooting route is automatically generated;
and (4) carrying out aerial triangulation processing on the high-resolution water engineering target image shot in the step (4) to obtain initial point cloud. If the measured area has areas with complexity or large fluctuation, when the images of the areas are subjected to same-name point matching, the number of matched points is very small, so that the points of the areas in the initial point cloud are very rare;
in step 5, automatic analysis of the flying area is performed according to the initial point cloud obtained by aerial triangulation, and the specific method is as follows:
dividing a fitting structural surface into regular grids, projecting all points of the initial point cloud onto an equivalent fitting structural surface, and then counting the number of points in each grid in the grids;
the grid distance is determined according to the shooting distance, the focal length, the image width and the pixel size:
wherein
Respectively are equivalent fitting structural surfaces
The pitch of the grid in the direction is,
which is the distance of the photograph to be taken,
is the focal length of the lens, and is,
is the width of the image, and is,
is the pixel size of the image;
for areas which are possibly complex or have large fluctuation of a water engineering target, if global shooting is carried out only once, the effect of final modeling is deficient, from the perspective of global quality control of three-dimensional reconstruction, close-distance supplementary shooting needs to be carried out on the areas, and the supplementary shooting route is automatically generated;
carrying out aerial triangulation processing on the high-resolution water engineering target image shot in the step 4 to obtain an initial point cloud; if the measured area has areas with complexity or large fluctuation, when the images of the areas are subjected to same-name point matching, the number of matched points is very small, so that the points of the areas in the initial point cloud are very rare;
the formula for projecting the point cloud to the equivalently fitted structural surface is as follows:
wherein
Fitting a construction surface for equivalenceIs determined by the parameters of (a) and (b),
as the coordinates of each point in the point cloud,
the coordinates after projection are obtained;
taking the maximum value P of the points of all gridsmaxThe threshold value is set to 1/3PmaxIf the number of the points is less than the threshold value, the grid is the area to be compensated;
and fitting the structural surface by using points in the grid and automatically calculating the three-dimensional flight path of the area to be compensated.
In addition, according to the automatic analysis method for the flying compensation area in the step 5, the fitting structural surface is divided into regular grids, all connection points obtained by aerial triangulation are projected onto the equivalent fitting structural surface, and then the average overlapping degree of the connection points in each grid is counted;
taking the value with the maximum average overlapping degree in all grids as OmaxThe threshold value is set to 1/3OmaxAnd the grid with the average overlapping degree value smaller than the threshold value is the area to be compensated.
Example (b):
the invention is explained in detail by applying the invention to a large hydropower station for unmanned aerial vehicle high-precision photography and quality control, and has a guiding function for applying the invention to other complicated structure water engineering unmanned aerial vehicle high-precision photography and quality control.
In this embodiment, the method for high-precision photography and quality control of the unmanned aerial vehicle of a large hydropower station includes the following steps:
step 1: according to the characteristics of the slope surface shape of a large hydropower station, manually operating a rotor unmanned aerial vehicle with RTK to shoot near four corner points of each surface of the large hydropower station to obtain geographic coordinates of the four corner points of a hydraulic engineering target (as shown in FIG. 2, a white frame part indicates the rotor unmanned aerial vehicle with RTK to shoot near the four corner points of each surface of the hydropower station);
step 2: calculating to obtain a fitting structural surface and a shooting range of each surface of a certain large hydropower station by using the unmanned aerial vehicle images of the four angular points obtained in the step 1;
step 3, calculating to obtain the shooting attitude of the unmanned aerial vehicle according to the fitting structural surface and the shooting range obtained in the step 2 and according to the angle of the surface and the set shooting parameters (shooting distance, overlapping degree and the like), and calculating to obtain the three-dimensional flight path of the unmanned rotorcraft (the shooting attitude of the man-machine and the three-dimensional flight path of the unmanned rotorcraft in the embodiment are shown in fig. 3), including the flying position of the unmanned aerial vehicle, the shooting angle of the camera, the exposure time interval and the like;
and 4, step 4: importing the three-dimensional flight path information obtained in the step 3 into a flight control system of the unmanned aerial vehicle, taking off the unmanned aerial vehicle, and automatically carrying out veneering photography according to the three-dimensional flight path information imported in the step 3 to obtain a high-resolution water project target image;
and 5: performing aerial triangulation processing according to the high-resolution water engineering target image obtained in the step 4 to obtain sparse point cloud; analyzing the sparse point cloud, checking whether an area with few abnormal points exists, automatically finding an area needing to be compensated for flying (namely the area with few abnormal points), taking out the area (the area to be compensated for flying, which is detected by the initial point cloud after the aerial triangulation in the embodiment, is shown as a white square in fig. 4), automatically fitting a structural surface of the area needing to be compensated for flying, and calculating a three-dimensional flight path of the unmanned aerial vehicle (the three-dimensional flight path of the area needing to be compensated for flying, which is automatically generated in the embodiment, is shown in fig. 6);
step 6: calculating the overlapping degree of each connecting point according to the aerial triangulation result obtained in the step 5; automatically analyzing the overlapping degrees of all the connecting points, checking whether an area with abnormally small overlapping degree exists, automatically finding out an area needing to be compensated, taking out the area (the area to be compensated and detected by the overlapping degrees of the connecting points after the aerial triangulation in the embodiment is shown as a black square in fig. 5), automatically fitting a construction surface and calculating a three-dimensional flight path of the unmanned aerial vehicle (the automatically generated three-dimensional flight path of the area needing to be compensated and in the embodiment is shown in fig. 6);
and 7: importing the three-dimensional flight path information obtained in the step 5 and the step 6 into a flight control system of the unmanned aerial vehicle, and automatically performing flight compensation on the area to obtain a corresponding high-resolution water engineering target image;
and 8: according to the high-resolution water engineering target image obtained in the steps 4 and 7 (in the embodiment, the image resolution is 1 mm to 8 mm (determined according to the specific shooting distance and the model of the unmanned aerial vehicle), the positioning accuracy of the unmanned aerial vehicle is centimeter level (determined according to the model of the specific unmanned aerial vehicle), accurate geometric positioning and fine dense matching are carried out, and a fine high-accuracy water engineering geographic information product is obtained.
And (4) conclusion: the embodiment can carry out the automation mechanized operation, and is easy and simple to handle, can acquire high resolution image fast and carry out quality control (automatic mend promptly) automatically, and overall efficiency is high, and three-dimensional flight path is just shooing the face to water works, has avoided texture compression and geometric deformation problem.
Verification test
The inventive examples (with quality control) were used as experimental groups, and the inventive examples (without quality control) were used as control groups.
The control group and the experimental group carry out the high-precision photography method of the hydropower station unmanned aerial vehicle, and the difference lies in that: the control group directly jumps from step 4 to step 8 without performing steps 5, 6 and 7.
The test results are as follows:
in the comparison group, automatic compensation is not carried out, and the three-dimensional modeling result based on the area needing compensation is shown as a white box in fig. 7, so that the turning part of the building is fuzzy and frayed;
in fig. 7, a small structural plane needs to be re-fitted at the part of the frame, and then a flying-supplementing three-dimensional flight path is automatically generated for flying-supplementing photography, so as to eliminate the situations of blurring and streaking at the turning part of the building.
In the experimental group, automatic compensation flight is performed, and the result of three-dimensional modeling based on the area needing compensation flight is shown as a white box in fig. 8, so that the building model is complete and fine.
Therefore, according to the embodiment, the area needing to be compensated is obtained through automatic analysis and calculation by utilizing the sparse distribution of the initial point cloud obtained through the aerial triangulation of the shot image and the overlapping degree of all the connecting points, and the corresponding three-dimensional flight path is automatically generated for compensation, so that the flight quality and the operation efficiency are more comprehensively ensured, and the problem of rework of the aviation flight field is avoided.
Other parts not described belong to the prior art.
Claims (4)
1. A high-precision shooting and quality control method for a water engineering unmanned aerial vehicle with a complex structure is characterized by comprising the following steps: comprises the following steps of (a) carrying out,
step 1: shooting by an unmanned aerial vehicle at four points;
operating a rotor unmanned aerial vehicle with RTK, and respectively carrying out conventional shooting at four angular points in a water engineering range to obtain four angular point images with high-precision positioning coordinates;
step 2: extracting the geographic coordinates of four corner points from the EXIF information of the four images obtained in the step 1;
and step 3: calculating the attitude of the construction surface and planning a flight path based on the construction surface;
according to the geographical coordinates of the four angular points of the water project obtained in the step 2, fitting the water project target by using a space construction surface to obtain a fitted construction surface, and then automatically calculating according to the normal vector angle of the surface and the set shooting parameters to obtain the shooting attitude and the three-dimensional track of the unmanned aerial vehicle;
and 4, step 4: automatic shooting by an unmanned aerial vehicle;
importing the three-dimensional flight path information obtained in the step (3) into a flight control system of the unmanned aerial vehicle, and automatically carrying out veneering photography by the flying unmanned aerial vehicle to obtain a high-resolution water engineering target image;
and 5: aerial triangulation processing and aerial triangulation result intelligent analysis;
and (3) aerial triangulation processing: performing aerial triangulation processing according to the high-resolution water engineering target image obtained in the step 4 to obtain an initial point cloud;
the aerial triangulation result intelligent analysis comprises a complementary shooting flight path planning based on sparse point analysis and a complementary shooting flight path planning based on connection point overlapping degree analysis;
complementary shooting flight path planning based on sparse point analysis: automatically analyzing the initial point cloud, and checking whether an area with few abnormal points exists; if the area exists, the area is taken out, and a structural surface is automatically fitted and a three-dimensional flight path for the unmanned aerial vehicle to fly in a supplementing manner is calculated; if not, jumping to step 6;
step 6: complementary shooting flight path planning based on the analysis of the overlapping degree of the connecting points;
calculating the overlapping degree of each connecting point according to the aerial triangulation result obtained in the step 5; automatically analyzing the overlapping degrees of all the connecting points, and checking whether an area with abnormally small overlapping degree exists;
if the area exists, the area is taken out, and a structural surface is automatically fitted and a three-dimensional flight path for the unmanned aerial vehicle to fly in a supplementing manner is calculated; skipping to step 7;
if not, jumping to step 8;
and 7: automatic supplementary shooting by the unmanned aerial vehicle;
importing the three-dimensional flight path information obtained in the step 5 and the step 6 into a flight control system of the unmanned aerial vehicle, automatically performing secondary flight path planning on the area needing to be compensated and shooting to obtain a high-resolution image corresponding to the compensated flight;
and 8: and (4) carrying out precise geometric positioning and precise dense matching according to the high-resolution images obtained in the step (4) and the step (7) to obtain a precise and high-precision water engineering geographic information product.
2. The high-precision shooting and quality control method for the unmanned aerial vehicle with the complicated structure for water engineering of claim 1, wherein the method comprises the following steps: and (3) determining the direction and range of the fitted structural surface according to the geographic coordinates obtained by the four corners corresponding to the four images shot by the unmanned aerial vehicle in the water project target range in the step 1.
3. The high-precision shooting and quality control method for the unmanned aerial vehicle with the complicated structure for water engineering of claim 1 or 2, which is characterized in that: in step 5, automatic analysis of the flying area is performed according to the initial point cloud obtained by aerial triangulation, and the specific method is as follows:
dividing a fitting structural surface into regular grids, projecting all points of the initial point cloud onto an equivalent fitting structural surface, and then counting the number of points in each grid in the grids;
the grid distance is determined according to the shooting distance, the focal length, the image width and the pixel size:
wherein
Respectively are equivalent fitting structural surfaces
The pitch of the grid in the direction is,
which is the distance of the photograph to be taken,
is the focal length of the lens, and is,
is the width of the image, and is,
is the pixel size of the image;
the formula for projecting the point cloud onto the fitted structured surface is:
wherein
In order to fit the parameters of the construction surface equivalently,
as the coordinates of each point in the point cloud,
the coordinates after projection are obtained;
taking the maximum value P of the points of all gridsmaxThe threshold value is set to 1/3PmaxIf the number of the points is less than the threshold value, the grid is the area to be compensated;
and fitting the structural surface by using points in the grid and automatically calculating the three-dimensional flight path of the area to be compensated.
4. The high-precision shooting and quality control method for the unmanned aerial vehicle with the complicated structure for water engineering of claim 3, wherein the method comprises the following steps: in step 6, automatic analysis of the fly-in area is performed according to the overlapping degree of all the connection points obtained by aerial triangulation, and the specific method is as follows:
according to the method in the step 5, dividing the fitting construction surface into regular grids, then projecting all the connection points to the equivalent fitting construction surface, and then counting the average overlapping degree of the connection points in each grid;
taking the value with the maximum average overlapping degree in all grids as OmaxThe threshold value is set to 1/3OmaxAnd the grid with the average overlapping degree value smaller than the threshold value is the area to be compensated.
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