CN111473774A - Unmanned aerial vehicle single-flight-zone oblique photography power line obstacle inspection method - Google Patents
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Abstract
The invention belongs to the field of photogrammetry, and particularly relates to a method for inspecting an obstacle of a single-flight oblique photography power line of an unmanned aerial vehicle. Carry out single taking oblique photography along the power line including utilizing unmanned aerial vehicle, its characterized in that: further comprising the steps of: restoring image pose information and a power line corridor earth surface model; determining the homonymous image point of the suspension point based on the plumb line and the nuclear line constraint, and calculating the three-dimensional coordinate of the suspension point of the power line; thirdly, recovering the space position of the power line point based on the vertical plane constraint; step four, complete space power line fitting is achieved by using a catenary equation; and step five, performing obstacle ranging analysis by using the space buffer area. The unmanned aerial vehicle single-flight-zone oblique photography type power line inspection system disclosed by the invention is used for carrying out power line inspection in a single-flight-zone oblique photography mode, recovering a space power line by utilizing the vertical plane constraint and carrying out space distance measurement by utilizing the buffer zone, and is simple to operate, high in precision and high in inspection efficiency.
Description
Technical Field
The invention relates to a method for inspecting an obstacle of a single-flight oblique photography power line of an unmanned aerial vehicle, belonging to the field of photogrammetry.
Technical Field
In recent years, with the rapid development of social economy and the rapid construction of urbanization, the demands for life and industrial electricity are increasing. The high-voltage transmission line is used as an important infrastructure of the country, and the safety of the transmission line is closely related to the daily life of people. The power transmission line has the characteristics of long distance, large coverage range and the like, and if maintenance and inspection are not timely, single-phase grounding or even short-circuit tripping of the power line caused by interference of surrounding trees is very easy to occur, so that power failure accidents are caused, and even fire can occur in severe cases. In order to prevent the power grid from safety accidents, the power line corridor needs to be regularly inspected.
At present, the main inspection modes of the power transmission line are as follows: manual inspection, airborne laser scanning inspection, ground mobile measurement inspection, helicopter inspection and unmanned aerial vehicle inspection. The manual inspection has the problems of high labor intensity, low efficiency, difficult management and the like; the airborne laser scanning has huge data amount and is very inconvenient to process, and the laser scanner has the characteristics of high cost, large danger coefficient and the like; the ground mobile measurement patrol is a highly integrated measurement system such as a Global Navigation Satellite System (GNSS), an inertial navigation system (IMU), three-dimensional laser scanning and the like, which can be carried or installed on an automobile by people, but a high-voltage transmission line is mainly positioned in an area lacking a transport network, so that the application of the ground mobile measurement system is limited; in the helicopter inspection, a high-resolution visible light camera and a high-precision POS are carried by the helicopter to inspect a power line corridor, but the helicopter needs a professional flight crew to drive, so that the cost and the risk coefficient are high; the unmanned aerial vehicle inspection is to carry a high-resolution visible light camera and a high-precision POS (point of sale) to inspect a power line corridor by the unmanned aerial vehicle. Compared with other inspection modes, the unmanned aerial vehicle inspection mode has the characteristics of low cost, high safety factor and the like, and therefore inspection of a large-area power line corridor can be realized by installing the visible light camera on the unmanned aerial vehicle. Zhengshui, Zhang Yong et al used unmanned aerial vehicles for power line inspection studies. Zhengshui et al propose a power line ranging based on the plumb line trajectory method, but the accuracy and stability of ranging are not high, and only the distance between the power line and the obstacle right below can be detected. Zhang Yong et al uses a multi-swath camera geometry that, while the same-name image points of the power line points can be determined using the epipolar lines, increases flight costs and computational complexity over single swath cameras.
Chinese patent application 201711115974.4 in the prior art discloses an automatic cruise power line detection unmanned aerial vehicle, in which a processor module performs noise reduction and contrast enhancement on each frame of image picture, and then converts the image picture into a binary image. And calculating the gradient value of each pixel in the binary image by convolution operation by using a differential operator aiming at the binary image, comparing the gradient value with a preset edge gradient threshold value, and determining the pixel with the gradient value higher than the edge gradient threshold value as an edge pixel. The detected edge pixels include pixels on two edges of each power line, and edge pixels in areas such as roads and ridges in the background. The method has the defects of low precision and large calculation amount.
Disclosure of Invention
The invention aims to solve the defects of the prior art and provides the method for inspecting the power line barrier of the single-flight oblique photography of the unmanned aerial vehicle, which has high inspection precision and high inspection efficiency.
In order to solve the technical problems, the invention adopts the following technical scheme: unmanned aerial vehicle single-flight oblique photography power line obstacle inspection method includes the steps that unmanned aerial vehicle is used for single-flight oblique photography along a power line, and the method is characterized in that: the method also comprises the following steps:
performing space-three matching adjustment on oblique images of a power line corridor by using an unmanned aerial vehicle differential GPS or/and ground control point data to obtain accurate internal and external orientation elements of each image, then generating dense point clouds through dense matching, and constructing an irregular triangular network for the generated dense point clouds to restore a ground surface three-dimensional model of the whole area of the power line corridor;
determining homonymous image points of the power line suspension points in adjacent images based on the plumb line and the nuclear line constraint, and calculating three-dimensional coordinates of the power line suspension points by utilizing space front intersection;
determining plumb surfaces where the power lines are located through three-dimensional coordinates of suspension points at two ends of the power lines, and calculating the spatial positions of points on the power lines based on plumb surface constraints;
step four, complete space power line fitting is achieved by using a catenary equation;
and step five, performing obstacle ranging analysis by using the space buffer area.
The terms "differential GPS" or "ground control point" are well known in the art. The two are in alternative relation, but can be used simultaneously if both data are available. Generally, the field measurement ground control points consume manpower, material resources and financial resources, so that the ground control points need to be measured only when the unmanned aerial vehicle is not provided with a differential GPS system, namely, the differential GPS data cannot be acquired.
The preferable scheme is as follows:
in order to achieve the purpose of the invention, in the step two, when the unmanned aerial vehicle collects data, suspension points shielded by the insulator may exist in images shot at different viewing angles. For suspension points shielded by the insulator, the coordinates of the image points cannot be directly measured. In order to accurately measure the coordinates of the image points of the suspension points, the invention utilizes the plumb line to carry out auxiliary measurement. According to the characteristic that a projection extension line of any plumb line in the space in an image certainly passes through a bottom point, a plumb line auxiliary suspension point coordinate measuring method is provided.
Let the coordinate of the image base point in the image plane be (x)d,yd) The coordinate of any point on the object plumb line where the suspension point is located in the image plane is (x)p,yp) Then, the mathematical equation of the projection of the plumb line in the image is:
determining a nuclear line where a suspension point shielded by the insulator is located by using a coplanar condition equation, wherein a mathematical equation of the nuclear line can be abbreviated as:
y＝(A/B)x+(C/B)f (2)
the combination formulas (1) and (2) can determine the coordinates of the image points of the suspension points shielded by the insulators on the corresponding images.
The images acquired by the unmanned aerial vehicle have high overlapping degree characteristic, so that the same tower pole can appear on a plurality of images, and the sequence images corresponding to the tower pole can be found by utilizing the internal and external orientation elements of the images obtained by solving the adjustment in the previous data preparation. And determining the suspension homonymous point by using the plumb line for the images. And after obtaining the coordinates of a plurality of image points with the same name of the suspension point, calculating the three-dimensional coordinates of the suspension point by using a multi-piece front intersection method.
In the third step, the three-dimensional coordinates of the suspension points at the two ends of the power line calculated by the intersection in the front direction are used for determining the vertical plane of the power line. The method for extracting the power line image space features under the complex background is used for realizing the automatic extraction of the power line image space features under the complex background. For any image point on the image side power line characteristic, a spatial light beam passing through the photographing center and the image point can be determined, and the power line is necessarily located in a vertical plane determined by suspension points at two ends, so that the intersection point of the spatial light beam and the vertical plane is the spatial power line point corresponding to the image point.
The AB coordinates of suspension points at two ends of the power line are respectively (X)1,Y1,Z1)、(X2,Y2,Z2) Then the equation for the vertical plane W is:
Mx+Ny+L＝0 (3)
wherein M ═ Y2-Y1；N＝X1-X2；L＝(X2-X1)Y1-(Y2-Y1)X1。
For any power line point p on the image, there is a light beam passing through the center of the image S and the point p, and if the coordinates of the image point p on the image are (x, y), the light beam can be expressed as:
wherein λ is a scale factor, R is the image rotation matrix, f is the image focal length, (X)S,YS,ZS) Is the spatial position of the image at the moment of photographing. Combined formula (3) andequation (4) can obtain the three-dimensional coordinates (X, Y, Z) of the power line space point P corresponding to the image point P, i.e. the three-dimensional position of the space power line point.
In order to achieve the purpose of the invention, in the fourth step, when the included angle between the photographing light and the vertical plane is small, the three-dimensional coordinate error of the obtained discrete point of the power line is difficult to control. By utilizing the characteristic that the power line is a catenary curve in a natural state, the method for performing least square fitting on initially acquired discrete points of the space power line by adopting the space parabolic model is provided, so that the reconstruction precision of the three-dimensional model of the space power line is further optimized and improved, and the space parabolic model is shown as a formula (5). Because the suspension points at the two ends of the power line are points obtained by calculating a plurality of pieces of forward intersection, the stability is high, and the weight of the suspension points is higher than that of the space power line points recovered by the constraint of the vertical plane in the least square fitting process. And obtaining a space power line with higher precision by least square fitting.
In step five, after the space power line is restored and the three-dimensional model of the earth surface is constructed, a space buffer area with the safe distance r as the radius is established by taking the power line as the center, and the space buffer area is analyzed. If the surface model of the partial area of the power line corridor is intersected with the power line space buffer area, the area can be judged to be an obstacle, and meanwhile, the specific area position where the obstacle exists is recorded.
Dividing the power line into n parts equally by taking theta as a step pitch, and representing the divided curve segment as theta1,θ2,θ3,…θn-1,θnWhen θ is sufficiently small, the curved line segment of each portion can be considered approximately as a straight line. When theta is knowni(Xi,Yi,Zi)、θi+1(Xi+1,Yi+1,Zi+1) Then there is thetaiθi+1Direction vector of
Assuming a power line corridor surface presence point D (X, Y, Z), if equation (6) is satisfied:
(Xi+1-At-X)2+(Yi+1-Bt-Y)2+(Zi+1-Ct-Z)2≤r2(0≤t≤1) (6)
point D is considered to be located within the spatial buffer of the power line and can be determined to be a discrete point of an obstacle in the power line corridor.
Compared with the prior art, the invention has the advantages that: the invention uses the single-flight-zone oblique photography mode of the unmanned aerial vehicle to carry out power line inspection, thereby reducing the data quantity and the data acquisition cost acquired by the unmanned aerial vehicle and improving the inspection and data processing efficiency; from the aspect of algorithm, the three-dimensional coordinates of the upper points of the power line in each image can be recovered based on a single image by utilizing the vertical plane constraint, the complete space power line between two towers is obtained through catenary equation fitting, and the power line buffer area is utilized for space distance measurement and obstacle judgment, so that the method has strong innovation and practicability.
The invention has low data acquisition cost, high data processing efficiency and simple operation, greatly improves the inspection efficiency and reduces the inspection cost of the power line barrier on the premise of ensuring the precision.
Drawings
FIG. 1 is a diagram of the fitting results of the present invention using the catenary equation to fit recovered spatial power line points;
FIG. 2 is a scanned point cloud of the present invention;
fig. 3 is a distance diagram of the power line and the underlying earth model of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
for reference, the invention provides a complete single-flight power line obstacle inspection process from image shooting. The invention provides a new technical scheme for full-automatic recovery of a space power line and analysis of a buffer area, which is a scheme capable of being automatically realized by adopting a computer means, except for image data acquisition and image point coordinates of a power line suspension point on an insulator. The technical scheme of the invention is explained by combining the drawings and the embodiment.
The method comprises the steps of firstly, performing space-three adjustment on images of a power line corridor by using a high-precision POS or ground control point to obtain accurate internal and external orientation elements of each image, then generating dense point clouds through dense matching, and constructing an irregular triangulation network for the generated dense point clouds, so that a ground surface three-dimensional model of the whole area of the power line corridor is recovered.
And step two, performing auxiliary measurement by using the plumb line. According to the characteristic that a projection extension line of any plumb line in the space in an image certainly passes through a bottom point, the plumb line auxiliary suspension point coordinate measuring method is provided.
The method for measuring the coordinates of the suspension points of the power line based on the plumb line assistance mainly comprises the following steps:
s1, measuring coordinates of image points in the image of which the suspension points are not shielded by the insulators;
s2, determining the homonymy epipolar line of the same suspension point on the shielded image through the internal and external orientation elements of the image;
s3, in the image of the suspension point shielded by the insulator, determining a plumb line where the suspension point is located by the aid of the vertical line;
s4, calculating the intersection point of the core line with the same name and the plumb line, and determining the coordinates of the suspension point image points shielded by the insulator;
s5, measuring coordinates of image points of the same suspension point on a plurality of images, and determining three-dimensional coordinates of the suspension point by using a multi-plate front intersection method.
For the coordinates of the suspension points shielded by the insulators, the coordinates (x) of the bottom point of the image in the image plane can be calculated by using the inside and outside orientation elements of the imaged,yd) Measuring the coordinate (x) of any point on the object plumb line where the suspension point is located in the image planep,yp) The projection mathematical equation of the plumb line in the image can be obtained:
the measured coordinates of the image points of the suspension points which are not shielded by the insulator, the center of the camera station and the center of the camera station of the image of the suspension point which is shielded by the insulator can be used for obtaining a nuclear surface, an intersection line exists between the nuclear surface and the image of the suspension point which is shielded by the insulator, the intersection line is a nuclear line, and the mathematical equation of the nuclear line can be abbreviated as follows:
y＝(A/B)x+(C/B)f
by combining the projection mathematical equation of the plumb line in the image and the mathematical equation of the epipolar line, the coordinates of the image points of the suspension points shielded by the insulator on the corresponding image can be determined, and after the coordinates of a plurality of image points with the same name of the same suspension point are obtained, the three-dimensional coordinates of the suspension points are calculated by using a multi-piece forward intersection method.
And step three, determining the vertical plane of the power line by using the three-dimensional coordinates of the suspension points at the two ends of the power line calculated by the front intersection. And the power line extraction method in the power line extraction method under the complex ground object background is utilized to realize the automatic extraction of the image side characteristics of the power line under the complex background.
Coordinates of suspension points at two ends of the power line can be calculated through the second step, and AB coordinates of the suspension points at the two ends are assumed to be (X) respectively1,Y1,Z1)、 (X2,Y2,Z2) Then the equation for the vertical plane W can be written as:
Mx+Ny+L＝0
wherein M ═ Y2-Y1；N＝X1-X2；L＝(X2-X1)Y1-(Y2-Y1)X1。
For any power line point p on the image, there is a light beam passing through the center of the image S and the point p, and if the coordinates of the image point p on the image are (x, y), the light beam can be expressed as:
wherein λ is a scale factor, R is the image rotation matrix, f is the image focal length, (X)S,YS,ZS) Is the space of the image in the shooting momentAnd (c) an intermediate position. Combining the equations (3) and (4), the three-dimensional coordinates (X, Y, Z) of the power line space point P corresponding to the image point P, i.e. the three-dimensional position of the space power line point, can be obtained.
And step four, by utilizing the characteristic that the power line is a catenary curve in a natural state, providing a method for performing least square fitting on initially acquired discrete points of the space power line by adopting a space parabolic model, so as to further optimize and improve the reconstruction precision of the three-dimensional model of the space power line, wherein the space parabolic model is shown as a formula (5). Because the suspension points at the two ends of the power line are points obtained by intersection calculation of a plurality of pieces of front parts, the stability is high, and the weight of the suspension points is higher than that of the space power line points recovered by the constraint of the vertical plane in the least square fitting process. And obtaining a space power line with higher precision by least square fitting.
And step five, analyzing the space buffer area. After the space power line is restored and the earth surface three-dimensional model is built, a space buffer area with a safe distance r as a radius is built by taking the power line as a center, and the space buffer area is analyzed. If the surface model of the partial area of the power line corridor is intersected with the power line space buffer area, the area can be judged to be an obstacle, and meanwhile, the specific area position where the obstacle exists is recorded.
Dividing the power line into n parts equally by taking theta as a step pitch, and representing the divided curve segment as theta1,θ2,θ3,…θn-1,θnWhen θ is sufficiently small, the curved line segment of each portion can be considered approximately as a straight line. When theta is knowni(Xi,Yi,Zi)、θi+1(Xi+1,Yi+1,Zi+1) Then there is thetaiθi+1Direction vector of
Assuming a power line corridor surface presence point D (X, Y, Z), if equation (6) is satisfied:
(Xi+1-At-X)2+(Yi+1-Bt-Y)2+(Zi+1-Ct-Z)2≤r2(0≤t≤1)
point D is considered to be located within the spatial buffer of the power line and can be determined to be a discrete point of an obstacle in the power line corridor
Experiments prove that
In order to verify the effectiveness of the single-aerial oblique photography power line obstacle inspection method provided by the invention, analog power line data are collected for testing.
Carrying an FC220 lens (the focal length of a camera is 4.78mm, the size of a sensor is 6.16 x 4.62mm, the image resolution is 4000 x 3000, and the pixel size is 1.54m) by using the Mavic Pro of the unmanned aerial vehicle in Dajiang, carrying out single-flight oblique photography along a power line, wherein the heading overlapping degree of the image is 80%, and the relative flight height of the unmanned aerial vehicle during data acquisition is 18 m; in addition, a Z + F IMAGER 5006h ground three-dimensional laser scanner is used for scanning an experimental area to obtain three-dimensional information of the power line corridor ground surface and the power line; and respectively acquiring 10 control points and 10 check points by using RTK. The three null differences adopt control point joint differences, the back projection error of three null encryption points is 0.645 (pixel), and the precision of the check points is shown in table 1.
TABLE 1 checkpoint accuracy
After the power line corridor surface model is recovered, a certain number of spatial power line points are recovered through the vertical plane constraint, the recovered spatial power line points are fitted by using a catenary equation, and the fitting result is shown in fig. 1, wherein two end points are suspension points of a power line, and a point spatial power line point between the two end points is arranged. The point cloud after scanning with the ground three-dimensional laser scanner is shown in fig. 2.
By using the method and the device, the surface model and the power line elevation of the power line corridor between the two towers can be obtained, a distance graph between the power line and the lower surface model (shown as a solid curve in fig. 3) can be drawn, and meanwhile, the distance graph between the power line and the lower surface model (shown as a dotted curve in fig. 3) can be drawn based on laser scanning data. As can be seen from FIG. 3, the distance measured by the present invention is consistent with the distance measurement result of laser scanning, and the distance measured by the present invention and the distance measured by laser scanning have a difference within a certain range in the 36-42.85m section, wherein the maximum error is 0.195 m. Tests show that the method can effectively detect the obstacles around the power line, and the precision can meet the precision requirement of the power department on the power line distance measurement.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principles of the present invention are intended to be included within the scope of the present invention. In the above, the inside and outside orientation elements, epipolar lines, multi-slice intersection methods, and constraints are well known techniques. Constraints are constraints based on plumb lines and epipolar lines.
Claims (8)
1. Unmanned aerial vehicle single-flight oblique photography power line obstacle inspection method includes the steps that unmanned aerial vehicle is used for carrying out single-flight oblique photography along a power line, and the method is characterized in that: further comprising the steps of:
performing space-three matching adjustment on oblique images of a power line corridor by using differential GPS data of an unmanned aerial vehicle to obtain accurate internal and external orientation elements of each image, then generating dense point clouds through dense matching, and constructing an irregular triangulation network on the generated dense point clouds to recover a surface three-dimensional model of the whole area of the power line corridor;
determining homonymous image points of the power line suspension points in adjacent images based on the plumb line and the nuclear line constraint, and calculating three-dimensional coordinates of the power line suspension points by utilizing space front intersection;
determining plumb surfaces where the power lines are located through three-dimensional coordinates of suspension points at two ends of the power lines, and calculating the spatial positions of points on the power lines based on plumb surface constraints;
step four, complete space power line fitting is achieved by using a catenary equation;
and step five, performing obstacle ranging analysis by using the space buffer area.
2. The unmanned aerial vehicle single-flight inclined photography power line obstacle inspection method according to claim 1, characterized in that: in the second step, the method for measuring the coordinates of the suspension points of the power line based on the plumb line assistance mainly comprises the following steps:
s1, measuring coordinates of image points in the image of which the suspension points are not shielded by the insulators;
s2, determining the homonymy epipolar line of the same suspension point on the shielded image through the internal and external orientation elements of the image;
s3, in the image of the suspension point shielded by the insulator, determining a plumb line where the suspension point is located by the aid of the vertical line;
s4, calculating the intersection point of the core line with the same name and the plumb line, and determining the coordinates of the suspension point image points shielded by the insulator;
s5, measuring coordinates of image points of the same suspension point on a plurality of images, and determining three-dimensional coordinates of the suspension point by using a multi-plate front intersection method.
3. The unmanned aerial vehicle single-flight inclined photography power line obstacle inspection method according to claim 1 or 2, characterized in that: the second step is specifically as follows:
let the coordinate of the image base point in the image plane be (x)d,yd) The coordinate of any point on the object plumb line where the suspension point is located in the image plane is (x)p,yp) Then, the mathematical equation of the projection of the plumb line in the image is:
determining a nuclear line where a suspension point shielded by the insulator is located by using a coplanar condition equation, wherein a mathematical equation of the nuclear line can be abbreviated as:
y＝(A/B)x+(C/B)f (2)
the combination formulas (1) and (2) can determine the coordinates of the image points of the suspension points shielded by the insulators on the corresponding images;
sequence images corresponding to the tower pole can be found by utilizing the inner and outer orientation elements, suspension homonymy points are determined by utilizing the plumb line for the images, after coordinates of a plurality of homonymy image points of the suspension points are obtained, three-dimensional coordinates of the suspension points are calculated by utilizing a multi-piece forward intersection method.
4. The unmanned aerial vehicle single-flight inclined photography power line obstacle inspection method according to claim 1, characterized in that: and step three, the method for determining the spatial position of the power line point based on the vertical plane constraint is to determine the vertical plane where the power line is located according to the three-dimensional coordinates of the suspension points at the two ends of the power line, for any image point on the power line in the image, a spatial light ray passing through the photographing center and the image point can be determined, the power line is certainly located in the vertical plane determined by the suspension points at the two ends, and the intersection point of the spatial light ray and the vertical plane is the spatial power line point corresponding to the image point.
5. The unmanned aerial vehicle single-flight inclined photography power line obstacle inspection method according to claim 4, characterized in that: the third step, the specific calculation method of the space position of the power line point based on the vertical plane constraint is that,
the AB coordinates of suspension points at two ends of the power line are respectively (X)1,Y1,Z1)、(X2,Y2,Z2) Then the equation for the vertical plane W is:
Mx+Ny+L＝0 (3)
wherein M ═ Y2-Y1；N＝X1-X2；L＝(X2-X1)Y1-(Y2-Y1)X1；
For any power line point p on the image, there is a light beam passing through the imaging center S and the point p, and if the coordinates of the image point of p on the image are (x, y), the light beam can be expressed as:
wherein λ is a scale factor, R is the image rotation matrix, f is the image focal length, (X)S,YS,ZS) The spatial position of the image at the moment of shooting;
combining the equations (3) and (4), the three-dimensional coordinates (X, Y, Z) of the power line space point P corresponding to the image point P, i.e. the three-dimensional position of the space power line point, can be obtained.
6. The unmanned aerial vehicle single-flight inclined photography power line obstacle inspection method according to claim 1, characterized in that: and step four, utilizing the characteristic that the power line is a catenary curve in a natural state, and adopting a method of performing least square fitting on initially acquired discrete points of the space power line by using a space parabolic model, so as to further optimize and improve the reconstruction precision of the three-dimensional model of the space power line, wherein the space parabolic model is as follows
As shown.
7. The unmanned aerial vehicle single-flight inclined photography power line obstacle inspection method according to claim 1, characterized in that: and step five, after the space power line is restored and the three-dimensional model of the earth surface is constructed, establishing a space buffer area with a safe distance r as a radius by taking the power line as a center, analyzing the space buffer area, judging that the area is an obstacle if the surface model of the partial area of the power line corridor is intersected with the space buffer area of the power line, and recording the specific area position of the obstacle.
8. The unmanned aerial vehicle single-flight inclined photography power line obstacle inspection method according to claim 1, characterized in that: and step one, performing space-three matching adjustment on the inclined images of the power line corridor by using the unmanned aerial vehicle differential GPS and ground control point data.
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| CN113763325A (en) * | 2021-08-03 | 2021-12-07 | 山东电力工程咨询院有限公司 | Spatial measurement method for height of tower and height of line hanging point in non-three-dimensional environment |
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