Method for locating the center point of the scattering spot of the transmission line and determining the adaptive imaging heading angle

Abstract

The application relates to the technical field of overhead transmission line remote sensing monitoring, in particular to a method for positioning a center point of a transmission conductor scattering spot and determining an adaptive imaging heading angle, wherein the method for positioning the center point of the transmission conductor scattering spot comprises the following steps: acquiring a positioning deviation of a synthetic aperture radar image to correct geometric positioning errors of transmission conductor imaging; calculating a transmission conductor radar imaging simulation result according to a three-dimensional geographic coordinate of the transmission conductor and a range-doppler positioning model; and obtaining a center point positioning result of the transmission conductor scattering spot according to the transmission conductor radar imaging simulation result. Therefore, the problem of accurately simulating and positioning the center point of the transmission conductor scattering spot in a radar remote sensing image is solved. In addition, the method can be used to simulate and calculate the accurate imaging position of the transmission conductor scattering spot under different SAR sensor heading angle conditions, realize the calculation of optimal and limit heading angles, and be used for unmanned aerial vehicle SAR cruise route planning and SAR satellite orbit design.

Description

Technical Field

[0001] This application relates to the field of remote sensing monitoring technology for overhead transmission lines, and in particular to a method for locating the center point of a scattering spot on a transmission conductor and determining the heading angle for an adaptive imaging method. Background Technology

[0002] SAR (Synthetic Aperture Radar) is an active microwave remote sensing technology that can operate even in adverse weather conditions (such as rain, fog, or at night), thus possessing all-weather, all-time monitoring capabilities. Given the all-weather, all-time monitoring capabilities of spaceborne and UAV-based SAR, wide-area real-time monitoring of power transmission lines can be achieved. However, in meter-resolution SAR images, power transmission lines sometimes exhibit speckled scattering characteristics rather than linear texture features. Therefore, determining the relationship between the scattering spots of power transmission lines and their three-dimensional geographical location remains a challenge. Currently, there is no relevant calculation method that can simulate and calculate the imaging location of the scattering spots using the actual geographical coordinates of the power transmission lines. When disasters such as icing, galloping, or floods cause breakage or changes in power transmission lines, it is impossible to determine whether the conductor / ground wire is in a normal state using the three-dimensional coordinates of the power transmission line and real-time monitoring radar remote sensing image data.

[0003] Some literature indicates that when the angle between the transmission line and the radar sensor's flight direction exceeds 10–20 degrees, the texture characteristics of the transmission line's scattering spots disappear (or become invisible). The main physical mechanism is that the excessively large angle between the radar incident direction and the transmission line's cross-section leads to a sharp attenuation of the scattered signal. Microwave anechoic chamber experiments and simulations both show that the radar wave scattered by the transmission line reaches its strongest signal when the radar wave incident direction is perpendicular to the transmission line's extension direction. However, there is a lack of relevant theories and methods for using this theory to determine the imaging location of the transmission line's scattering spots. Currently, it is impossible to determine the specific location of the transmission line's scattering spots using the transmission line's geographical coordinates, radar image parameters, and other information, making it difficult to guide radar remote sensing technology in monitoring and evaluating the condition of transmission lines. In particular, it is impossible to determine how the radar flight direction adapts to the transmission line's extension direction, and under what radar sensor flight heading angle conditions, it is possible to adapt to the imaging of the transmission line's scattering spots. Summary of the Invention

[0004] This application provides a method for locating the center point of a power transmission line scattering spot and determining the imaging adaptation heading angle. It solves the problem of accurately simulating and calculating the center point of the scattering spot. This center point location method can determine the azimuth angle of the radar sensor to achieve radar imaging of the scattering spot, and estimates the radar sensor heading angle under positive and negative limit angle conditions, as well as the center point location of the scattering spot under the optimal heading angle condition. This method solves the problem of determining a suitable flight path for power transmission line monitoring, and is suitable for simulation calculations on both UAV SAR platforms and spaceborne SAR platforms.

[0005] The first aspect of this application provides a method for locating the center point of a transmission line scattering spot, comprising the following steps: acquiring the positioning deviation of a synthetic aperture radar image; correcting the geometric positioning error of the transmission line image based on the positioning deviation; calculating a radar imaging simulation of the transmission line based on the corrected geometric positioning error, a three-dimensional geographic coordinate point set of the transmission line, and a range-Doppler positioning model; and locating the center point of the transmission line scattering spot based on the radar imaging simulation.

[0006] Optionally, obtaining the positioning deviation of the synthetic aperture radar (SAR) image includes: obtaining the imaging parameters of the SAR image and the geographic coordinates of the ground control points in the SAR image; using the imaging parameters of the SAR image and the range-Doppler positioning model, calculating the geometric positioning coordinates of the center point of the scattering spot of the transmission line based on the radar imaging simulation positioning of the ground control points in the radar coordinate system; determining the positioning deviation of the SAR image based on the radar scattering imaging center point coordinates and the geometric positioning coordinates of the ground control points, wherein the radar scattering imaging center point coordinates of the ground control points are the coordinates of the extreme point of scattering intensity within the preset range of the ground control point target, and the positioning deviation of the radar image is used to correct the geometric positioning of the SAR image.

[0007] Optionally, the radar imaging simulation results of the transmission line are calculated based on the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line, and the range-Doppler positioning model. This includes: obtaining the radar imaging coordinate point set of the transmission line in the radar coordinate system based on the three-dimensional geographic coordinate point set of the transmission line, the corrected geometric positioning error, and the range-Doppler model; and obtaining the radar imaging simulation formula of the transmission line by fitting the radar imaging coordinate point set of the transmission line, wherein the radar imaging simulation formula of the transmission line is a parabolic function or a hyperbolic function.

[0008] Optionally, the center point of the transmission line scattering spot is located according to the radar imaging simulation, including: solving for the center point position of the scattering spot based on the transmission line radar imaging simulation and the condition that the center point of the scattering spot satisfies the azimuth parallel tangent equation or the condition that there is an extreme point in the range direction; when the transmission line radar imaging simulation is a parabolic equation, the coordinate point that satisfies the azimuth parallel tangent equation condition is used as the center point of the transmission line scattering spot; when the transmission line radar imaging simulation is a hyperbolic equation, the coordinate point that satisfies the condition that there is an extreme point in the range direction is used as the center point of the transmission line scattering spot.

[0009] A second aspect of this application provides a method for determining the heading angle in transmission line scattering spot adaptation imaging, comprising the following steps: horizontally rotating the extension direction of the transmission line clockwise, simulating the geographical coordinates of the rotated transmission line, locating the center point of the transmission line scattering spot based on the center point positioning method of the transmission line scattering spot described in the above embodiment, and using the heading angle when the center point of the transmission line scattering spot is located at the transmission line mounting point as the negative direction limiting heading angle for transmission line scattering spot adaptation imaging; horizontally rotating the extension direction of the transmission line counterclockwise, simulating the geographical coordinates of the rotated transmission line, and using the center point positioning method of the transmission line scattering spot described in the above embodiment as the negative direction limiting heading angle for transmission line scattering spot adaptation imaging. The method for locating the center point of the scattering spot locates the center point of the transmission line scattering spot. The heading angle when the center point of the transmission line scattering spot is located at the mounting point of the transmission line is taken as the positive limiting heading angle for the adaptation imaging of the transmission line scattering spot. When the extension direction of the horizontal rotating conductor is consistent with the flight direction of the radar sensor, the geographical coordinates of the rotated transmission line are obtained by simulation. Based on the method for locating the center point of the transmission line scattering spot in the above embodiment, the angle when the center point of the transmission line scattering spot is located at the midpoint of the mounting points at both ends of the transmission line is taken as the optimal heading angle for the adaptation imaging of the transmission line scattering spot.

[0010] Optionally, the method for calculating the negative direction limiting heading angle is as follows: calculate the distance from the center point of the transmission line scattering spot to the mounting points at both ends of the transmission line; the heading angle when the distance between the center point of the transmission line scattering spot and the mounting point at the end of the clockwise rotating transmission line extension direction is zero is taken as the negative direction limiting heading angle for transmission line scattering spot adaptation imaging.

[0011] Optionally, the method for calculating the positive direction limiting heading angle includes the following steps: calculating the distance from the center point of the transmission line scattering spot to the mounting points at both ends of the transmission line; the heading angle when the distance between the center point of the transmission line scattering spot and the mounting point at the end of the counterclockwise rotating transmission line extension direction is zero is taken as the positive direction limiting heading angle for the transmission line scattering spot adaptation imaging.

[0012] Optionally, the optimal heading angle for the transmission line scattering spot adaptation imaging is calculated as follows: the angular offset of the transmission line scattering spot adaptation imaging is determined based on the center point of the transmission line scattering spot; the optimal heading angle is calculated based on the angular offset and the current angle of the transmission line scattering spot adaptation imaging.

[0013] A third aspect of this application provides a device for locating the center point of a power transmission line scattering spot. This device is applied to a sensor platform and includes: an acquisition module for acquiring the positioning deviation of a synthetic aperture radar image; a calculation module for correcting the geometric positioning error of the power transmission line image based on the positioning deviation, and calculating a radar imaging simulation of the power transmission line based on the corrected geometric positioning error, a set of three-dimensional geographic coordinate points of the power transmission line, and a range-Doppler positioning model; and a positioning module for locating the center point of the power transmission line scattering spot based on the radar imaging simulation.

[0014] A fourth aspect of this application provides a heading angle determination device for transmission line scattering spot adaptation imaging. This device is applied to a data center or sensor scheduling platform and includes: a first determining module, used to horizontally rotate the extension direction of the transmission line clockwise, simulate the geographical coordinates of the rotated transmission line, locate the center point of the transmission line scattering spot based on the aforementioned transmission line scattering spot center point positioning device, and use the heading angle when the center point of the transmission line scattering spot is located at the transmission line mounting point as the negative direction limiting heading angle for transmission line scattering spot adaptation imaging; and a second determining module, used to horizontally rotate the extension direction of the transmission line counterclockwise, simulate the geographical coordinates of the rotated transmission line. The first module locates the center point of the transmission line scattering spot using the aforementioned center point positioning device, and uses the heading angle when the center point of the transmission line scattering spot is located at the transmission line mounting point as the positive limiting heading angle for transmission line scattering spot adaptation imaging. The second module is used to simulate the geographical coordinates of the rotated transmission line when the horizontal rotating conductor's extension direction is consistent with the radar sensor's flight direction. Based on the aforementioned center point positioning device, it locates the center point of the transmission line scattering spot, and uses the angle when the center point of the transmission line scattering spot is located at the midpoint between the two mounting points of the transmission line as the optimal heading angle for transmission line scattering spot adaptation imaging.

[0015] Therefore, this application has at least the following beneficial effects:

[0016] This application's embodiments can accurately simulate and locate the center point of the radar imaging scattering spot of overhead power transmission conductors / ground wires. Based on ground-based image control points, it corrects the positioning deviation of synthetic aperture radar (SAR) images, thereby enabling the geographical coordinates of the power transmission conductors to be accurately simulated in the radar imaging coordinate system. This achieves high-precision positioning of the center point of the power transmission conductor scattering spot in SAR images. The center point of the scattering spot is obtained by utilizing the extreme value characteristics of the function in the power transmission conductor simulation formula. Using the geographical coordinates of the power transmission conductor obtained by simulating the extension direction of the conductor clockwise and counterclockwise, and the center point positioning method of the scattering spot described in this application, the positive and negative limit values ​​of the radar sensor's heading angle can be determined. That is, heading azimuth angles outside these limit values ​​will not form a scattering spot. Simultaneously, the center point position of the scattering spot under the optimal heading angle condition can be simulated and calculated. This can be applied to SAR satellite remote sensing monitoring of power transmission conductors, especially for planning the flight paths of UAVs and spaceborne SAR, for adaptive imaging of the scattering spot. On the other hand, when the flight path planning software and satellite orbit analysis software plan the flight path of the SAR sensor, this application can realize the accurate simulation and positioning of the center position of the transmission line scattering spot, thereby providing a theoretical basis for the actual measurement of the transmission line scattering spot, and providing a reference for early warning when the transmission line scattering spot has a large positional deviation under disaster conditions such as transmission line breakage and wind deflection.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0019] Figure 1 This is a flowchart illustrating a method for locating the center point of a scattering spot on a power transmission line according to an embodiment of this application.

[0020] Figure 2 This is an example of a three-dimensional point cloud of a power transmission line in a certain area according to an embodiment of this application;

[0021] Figure 3 This is a schematic diagram of a simulation function for a power transmission line according to an embodiment of this application;

[0022] Figure 4 This is a solution diagram for the center point of transmission line cluster imaging based on azimuth tangent additional constraints according to an embodiment of this application;

[0023] Figure 5 This is a simulation result diagram of all transmission lines in a certain area under TSX and CSK images according to an embodiment of this application;

[0024] Figure 6 A flowchart is provided for a method for determining the heading angle of a transmission line scattering spot adaptation imaging according to an embodiment of this application;

[0025] Figure 7 This is a schematic diagram showing the angle between the satellite's heading and the power transmission line's direction, according to one embodiment of this application.

[0026] Figure 8 This is an example diagram of the simulation function of the transmission line under different heading angles in a certain area and the imaging center point under additional azimuth constraints, according to an embodiment of this application. Detailed Implementation

[0027] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0028] The following description, with reference to the accompanying drawings, describes a method for locating the center point of a transmission line scattering spot and a simulation application method according to embodiments of this application. Addressing the problems mentioned in the background art, this application provides a method for locating the center point of a transmission line scattering spot. This method can accurately simulate and locate the center point of the scattering spot in radar imaging of overhead transmission conductors / ground wires. It corrects the positioning deviation of synthetic aperture radar images based on ground-based image control points, thereby enabling the geographical coordinates of the transmission line to be accurately simulated in the radar imaging coordinate system, achieving high-precision location of the center point of the transmission line scattering spot in SAR images.

[0029] Specifically, Figure 1 This is a flowchart illustrating a method for locating the center point of a scattering spot on a power transmission line, as provided in an embodiment of this application.

[0030] like Figure 1 As shown, the method for locating the center point of the scattering spot on the transmission line includes the following steps:

[0031] In step S101, the positioning deviation of the synthetic aperture radar image is obtained.

[0032] In this embodiment of the application, the power transmission conductor is responsible for transmitting electrical energy, while the power transmission ground wire mainly serves to protect against lightning strikes and is partially wrapped with optical fiber to provide communication capabilities, thereby ensuring the safe operation of the power transmission line.

[0033] In one embodiment of this application, obtaining the positioning deviation of a synthetic aperture radar (SAR) image includes: obtaining the imaging parameters of the SAR image and the geographic coordinates of ground control points in the SAR image; calculating the geometric positioning coordinates of the geographic coordinates of the ground control points in the radar coordinate system using the imaging parameters of the SAR image and a range-Doppler positioning model; and determining the positioning deviation of the SAR image based on the radar scattering imaging center point coordinates and the geometric positioning coordinates of the ground control points, wherein the radar scattering imaging center point coordinates of the ground control points are the coordinates of the extreme point of scattering intensity within a preset range of the ground control point target, and the positioning deviation of the radar image is used to correct the geometric positioning of the SAR image.

[0034] It is understood that the embodiments of this application can obtain the coordinates of the ground control points actually measured for the transmission line; determine the geometric positioning coordinates of the transmission line in the radar coordinate system using the imaging parameters of synthetic aperture radar imagery and the range Doppler model; and, based on the high-precision geographic coordinates of the actually measured ground control point C, mark the ellipsoidal coordinates of this point as C0. (B,L,H) ;

[0035] The sub-pixel coordinates C of point C in the SAR coordinate system are obtained using SAR image imaging parameters and the range Doppler model. g(a,r) By oversampling by more than 10 times, the maximum value search method is used to obtain the sub-pixel-level accurate coordinates of the extreme point of scattering intensity within the preset range of the target point C at control point C. s(a,r) The sub-pixel center coordinates C of control point C were calculated using the Doppler model and measured geographic coordinates. g(a,r) And the sub-pixel center coordinates C obtained from the extreme point of scattering intensity. s(a,r) Obtain the deviation ε of the positioning sub-pixel accuracy in the azimuth and range directions of SAR images. (a,r) ε (a,r) =C s(a,r) -C g(a,r) ;

[0036] In step S102, the geometric positioning error of the transmission line imaging is corrected according to the positioning deviation, and the radar imaging simulation formula of the transmission line is calculated based on the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line, and the range Doppler positioning model.

[0037] In this embodiment of the application, the ellipsoidal coordinate expression of the set of geographical coordinate points of the transmission line i can be denoted as i [BLH] The geocentric coordinate system expression of the point set is denoted as i. [XYZ] Using SAR imagery parameters and a range-Doppler model, taking into account the azimuth and range offsets ε... (a,r) The image point set of the power transmission line in the radar coordinate system is obtained: i [ar] .

[0038] Specifically, this application embodiment can be described in detail with reference to a specific embodiment of the transmission line area implementation process, including the following steps:

[0039] Based on the known 3D point cloud of a certain power transmission line area, as shown below... Figure 2 As shown, there are 8 power transmission lines in this area, so i = A, B, C, D, E, F, M, N. The high-precision geographic coordinates Ci of a typical ground-based image control point, streetlight C, are taken. (X,Y,z) The vector at the rectangular position in geocentric space is denoted as R. C (C X C Y C Z ) T ; Corresponding to the imaging time t at point C i The instantaneous position vector of the SAR satellite in the geocentric rectangular coordinate system is represented by the position vector R. S denoted as (S) X ,S Y ,S Z ) T ;

[0040] R C With R S Satisfies the range-Doppler equation:

[0041]

[0042] Among them, V S Let S be the velocity vector of the SAR sensor S, which contains components in three directions: and λ is the radar wavelength, f d For t i The frequency shift of the radar echo signal at any given time, R i Then it is point Ct i The slant distance from the satellite at any given moment;

[0043] Using SAR satellite orbital data with centimeter-level accuracy, R in Equation 1 i Iterative solutions can pinpoint the location to the centimeter level, with the corresponding imaging time t. i Accuracy can be achieved to the order of better than 0.1 nanoseconds; C (X,Y,Z) According to the distance-Doppler equation, find R and t corresponding to this point. i And calculate the reference coordinate value C in the radar coordinate system. (a,r) Accurate to the sub-pixel level, as shown in the following formula:

[0044]

[0045] Where R0 is the slant range of the nearest point corresponding to the first column of pixels in the SAR image, and ρr t0 represents the azimuth spatial resolution of the radar. t0 is the initial sampling time of the azimuth direction corresponding to the first row of pixels in the SAR image, Az is the number of views in the azimuth direction, and PRF is the radar pulse repetition frequency.

[0046] Furthermore, embodiments of this application employ local oversampling, such as using the coordinate values ​​of reference point C (C... a C r Centered on point C, for example, a 20*20 window is selected, and oversampling is performed by a factor of 10. Within the oversampled window, the maximum value search method is used to traverse and find the point with the maximum scattering intensity, thus obtaining the radar scattering imaging center point C of the reference point C. g Pixel coordinates The sub-pixel center coordinates (C0) of control point C were calculated using the Doppler model and measured geographic coordinates. a C r ), and the sub-pixel center coordinates obtained by the maximum value search method. The positioning deviation for obtaining sub-pixel precision in SAR images: ε (a,r) =C s(a,r) -C g(a,r)

[0047] Further, the positioning deviation can be obtained from the TSX imagery of a certain area.

[0048] The positioning deviation can be obtained from the CSK imagery of a certain area.

[0049] The embodiments of this application can utilize SAR image imaging parameters and a range-Doppler model, while taking into account the azimuth and range deviations ε. (a,r) To obtain the imaging point set of each transmission line's three-dimensional point set in the SAR coordinate system: i [ar] .

[0050] In one embodiment of this application, the radar imaging simulation results of the transmission line are calculated based on the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line, and the range Doppler positioning model. This includes: obtaining the radar imaging coordinate point set of the transmission line in the radar coordinate system based on the three-dimensional geographic coordinate point set of the transmission line, the corrected geometric positioning error, and the range Doppler model; and obtaining the radar imaging simulation formula of the transmission line by fitting the radar imaging coordinate point set of the transmission line, wherein the radar imaging simulation formula of the transmission line is a parabolic function or a hyperbolic function.

[0051] In this embodiment, the radar imaging simulation formula for the power transmission line can be a quadratic polynomial function or a hyperbolic function. This embodiment calculates the azimuth and range coordinates of any point on the power transmission line in the radar coordinate system based on the imaging parameters of the synthetic aperture radar image and the range-Doppler model; and determines the equation coefficients of the target simulation formula by fitting the azimuth and range coordinates.

[0052] Specifically, the simulation formula f for obtaining the set of imaging points in the radar coordinate system for any transmission line i is... i (j a ), Figure 3 Simulation function f for transmission line i i (j a ) Schematic diagram. If simulation f i (j a When ) is a quadratic polynomial function, where j a Let f be the azimuth coordinate of any point j on the traverse in the radar coordinate system. i (j a Let be the range coordinate of any point j on the traverse i in the radar coordinate system, and find the polynomial coefficients β1, β2, β3;

[0053] In the TSX imagery of a certain area, taking transmission line A as an example,

[0054] In the CSK imagery of a certain area, taking transmission line A as an example,

[0055] In step S103, the center point of the scattering spot of the power transmission line is located based on the radar imaging simulation.

[0056] In this embodiment, the location of the center point of the scattering spot can be determined based on the radar imaging simulation formula of the transmission line and the condition that the center point of the scattering spot satisfies the azimuth parallel tangent equation or the condition that there is an extreme point in the range direction. When the radar imaging simulation formula of the transmission line is a parabolic equation, the coordinate point that satisfies the condition of the azimuth parallel tangent equation is used as the center point of the scattering spot of the transmission line. When the radar imaging simulation formula of the transmission line is a hyperbolic equation, the coordinate point that satisfies the condition that there is an extreme point in the range direction is used as the center point of the scattering spot of the transmission line.

[0057] Specifically, embodiments of this application can utilize simulation-based f i (j a Using the additional constraint conditions of the azimuth tangent, the center coordinates S of the transmission line imaging spot are obtained. (a,r) Specifically, it includes the following steps:

[0058] If we define the simulation function f, the simulation expression is... i (ja When f is a quadratic polynomial function, the additional constraint condition f based on the azimuth tangent equation is... i ′(j a ) = 0;

[0059] like Figure 4 As shown, according to f i ′(j a To obtain the simulation formula f, we need to set ) = 0. i (j a The value point under this constraint is the simulation calculation result S of the center point of the SAR scattering spot on the transmission line. (a,r) :

[0060] Output the maximum value S a and the corresponding S r That is, the distance to the extreme point S (a,r) The result is the simulation calculation of the center point of the SAR scattering spot on the transmission line.

[0061] In the TSX imagery of a certain area, taking transmission line A as an example,

[0062] In the CSK imagery of a certain area, taking transmission line A as an example,

[0063] like Figure 5 The image shows the simulation results of all transmission lines in a certain area under TSX and CSK images. Figure 5 a represents the simulation of the TSX satellite's power transmission line i in SAR imagery. i (j a The simulation diagram shows that i = A, B, C, D, E, F, M, N. Figure 5 b is a simulation diagram of the eight power transmission lines under the CSK satellite; Figure 5 The enlarged view in the middle is a schematic diagram of solving the center point of the transmission line beam imaging under additional azimuth constraints. Figure 5 a represents the f region under the TSX satellite. i ′(j a The center point of the image when ) = 0. Figure 5 b represents f under the CSK satellite i ′(j a The circle with 0 represents the calculated coordinates of the center point of the scattering spot, and the bottom represents the scattering spot region corresponding to the transmission line.

[0064] Furthermore, embodiments of this application can be based on the coordinates S of the center of the SAR scattering spot of the transmission line in the radar coordinate system. (a,r) Find the location of the point mapped onto the transmission line in geographic coordinates, i.e., the three-dimensional coordinates S of that point. (B,L,H) .

[0065] In one embodiment of this application, after locating the center point of the scattering spot of the power transmission line according to the radar imaging simulation, when simulating the change of the SAR heading angle, this embodiment of the application can project the three-dimensional point cloud coordinates of the power transmission line along the vertical line to the horizontal XOY plane in the spatial rectangular coordinate system, and obtain the expression of the power transmission line in the plane: y = k1*x + k2, where (x,y) are the longitudinal and abscissa coordinates of the power transmission line in the local rectangular coordinate system. Based on the expression y, the angle ξ between the extension direction of the power transmission line and the north direction is calculated: ξ = arctan(k1).

[0066] Horizontally rotate the conductor's extension direction clockwise by an angle μ, so that the angle between the extension direction of the transmission conductor and the north direction is ξ-μ degrees. Horizontally rotate the conductor's extension direction counterclockwise by an angle μ, so that the angle between the extension direction of the transmission conductor and the north direction is ξ+μ degrees.

[0067] The expression for the transmission line y under the angle ξ±μ is calculated through simulation. Based on computational efficiency and requirements, several points are typically selected at point cloud intervals of 0.1 to 5 m to form a point set Q. [xy] Keeping the elevation information of the corresponding number of the conductor point cloud unchanged, obtain the three-dimensional point cloud data Q of the transmission conductor at the angle ξ±μ. [xyz] The simulation yielded the geographical coordinates of the rotated transmission line, and Q was used to... [xyz] Point set Q transformed to ellipsoidal coordinate system [BLH] .

[0068] Furthermore, embodiments of this application can correct SAR image positioning deviations based on ground-based image control points, and then use a range-Doppler model to calculate the point set Q. [BLH] The imaging point set Q in radar imagery [ar] Simulation results;

[0069] Based on Q [ar] The simulation formula f for obtaining the set of imaging points in the radar coordinate system for transmission line i. i (j a ); using f i (j a Using the additional constraint conditions of the azimuth tangent, the imaging position of the SAR scattering spot center point of the transmission line when the direction angle of the transmission line is ξ+μ is obtained, which is the simulation application of the scattering spot center imaging point position.

[0070] The method for locating the center point of scattering spots of power transmission lines proposed in the embodiments of this application simulates the imaging point set in the synthetic aperture radar image based on the positioning deviation correction of the synthetic aperture radar image by ground image control points, thereby realizing the simulation of the center point coordinates of SAR scattering spots of different power transmission lines, improving the positioning accuracy of the center point of scattering spots of power transmission lines in SAR images, and can be used in the application scenario of SAR satellite remote sensing monitoring of power transmission lines.

[0071] Secondly, this application also proposes a method for determining the heading angle of transmission line scattering spot adaptation imaging, which includes the following steps:

[0072] In step S601, the extension direction of the conductor is rotated clockwise horizontally, and the geographical coordinates of the transmission conductor after rotation are simulated. The center point of the transmission conductor scattering spot is located based on the center point positioning method of the transmission conductor scattering spot in the above embodiment. The heading angle when the center point of the transmission conductor scattering spot is located at the mounting point of the transmission conductor is taken as the negative direction limit heading angle for the adaptation imaging of the transmission conductor scattering spot.

[0073] In step S602, the extension direction of the conductor is rotated counterclockwise horizontally, and the geographical coordinates of the conductor after rotation are simulated. The center point of the conductor scattering spot is located based on the center point positioning method of the conductor scattering spot in the above embodiment. The heading angle when the center point of the conductor scattering spot is located at the conductor mounting point is taken as the positive direction limit heading angle for the conductor scattering spot adaptation imaging.

[0074] It is understood that, in the embodiments of this application, the transmission line extension direction can be rotated clockwise or counterclockwise based on the target direction to generate the simulation results of the imaging point set of the transmission line in the radar coordinate system.

[0075] The target direction can be north.

[0076] Understandably, in a spatial rectangular coordinate system, the three-dimensional point cloud coordinates of the transmission line are projected onto the XOY plane, and the expression y of the transmission line in this plane is obtained by fitting, where (x,y) are the longitudinal and abscissa coordinates of the transmission line in the local rectangular coordinate system. The angle ξ between the extension direction of the transmission line and the north direction is calculated; the heading angle parameter θ of the SAR image is obtained, and the angle η between the direction of the line ξ and the heading angle θ is calculated: η=θ-ξ. Figure 7 a shows the original angle between the traverse direction and the heading angle in a certain area, where η = 4°;

[0077] Using clockwise as the negative direction and counterclockwise as the positive direction, set the rotation angle correction value μ in increments of 1 to 5°. i , such that η±μ i Within the ±20° range, a series of different values ​​of μ were obtained. i ; Rotate the direction of the transmission line by an angle μ clockwise or counterclockwise, with the north direction as the reference. i This causes the transmission line's direction angle to reach ξ±μ i The expression y for simulating the transmission line is obtained by keeping the point cloud elevation value constant, and obtaining the transmission line at ξ±μ. i A 3D point cloud dataset at a specific angle.

[0078] Furthermore, in this embodiment, the extension direction of the power transmission line can be rotated by an angle μ clockwise or counterclockwise with north as the reference direction. i This causes the transmission line's direction angle to reach ξ±μ i Degree, calculate the expression y obtained by projecting the transmission line onto the horizontal plane, such as Figure 7 As shown in b; keeping the point cloud elevation value constant, obtain the transmission line at ξ±μ i 3D point cloud dataset Q at angle [BLH] ;

[0079] Based on the above embodiment, the center point positioning method for the scattering spot of the transmission line is used to locate the coordinates of the center point of the scattering spot of the transmission line and obtain the coordinate positions of the mounting points at both ends of the transmission line.

[0080] This application embodiment can calculate the direction angle of a single transmission conductor as ξ±μ from the three-dimensional coordinate point cloud data of the transmission conductor at the simulated angle ξ±μ. i At that time, the coordinates of the center point of the SAR scattering spot on the transmission line can be obtained at different μ values. i corresponding Obtain ξ±μ i Three-dimensional coordinates of the mounting points at both ends of the transmission line at the specified angle.

[0081] Furthermore, in this embodiment of the application, the sub-pixel-level geometric positioning coordinates C of the ground image control point C obtained from on-site measurements can be calculated using SAR image imaging parameters and a range Doppler model. g(a,r) The coordinates Co of the image center point Co in the SAR image are obtained by using local oversampling and maximum value search methods. s(a,r) ; Compare the geometric coordinates of control point C to the image. g(a,r) and the coordinates of the imaging center point C s(a,r) Obtain the geometric positioning deviation ε of sub-pixel accuracy in SAR images. (a,r) Using SAR image imaging parameters and a range-Doppler model, while taking into account image geometric positioning errors, the following is calculated: Three-dimensional coordinates in the radar coordinate system

[0082] This application embodiment can identify the positive limiting heading angle when the coordinates of the center point of the transmission line scattering spot reach the coordinates of the mounting point, with counterclockwise as the positive direction; and identify the negative limiting heading angle when the coordinates of the center point of the transmission line scattering spot reach the coordinates of the mounting point, with clockwise as the negative direction; and determine the limiting range of the satellite heading angle based on the positive and negative limiting heading angles, specifically:

[0083] In this embodiment, with counterclockwise as the positive direction, after simulating the rotation angle μ of the transmission line's extension direction, the coordinate point set of the three-dimensional point cloud data of the transmission line in the radar coordinate system is obtained. The imaging position of the center point of the SAR scattering spot of the transmission line in the radar coordinate system is then calculated. When it reaches the mounting point at one end of the transmission line, it represents the SAR satellite's limiting heading angle θ in the counterclockwise direction. m Using clockwise as the negative direction, the simulation yields the coordinate set of the three-dimensional point cloud data of the power transmission line in the radar coordinate system after rotating the extension direction of the power transmission line by an angle μ. The imaging position of the center point of the SAR scattering spot of the power transmission line in the radar coordinate system is then calculated. When it reaches the mounting point at one end of the power transmission line, it represents the limiting SAR satellite heading angle θ in the clockwise direction. n ;

[0084] In actual implementation, the method for calculating the negative direction limiting heading angle is as follows: calculate the distance from the center point of the transmission line scattering spot to the mounting points at both ends of the transmission line; the heading angle when the distance between the center point of the transmission line scattering spot and the mounting point at the end of the clockwise rotating transmission line extension direction is zero is taken as the negative direction limiting heading angle for transmission line scattering spot adaptation imaging. The method for calculating the positive direction limiting heading angle includes the following steps: calculate the distance from the center point of the transmission line scattering spot to the mounting points at both ends of the transmission line; the heading angle when the distance between the center point of the transmission line scattering spot and the mounting point at the end of the counterclockwise rotating transmission line extension direction is zero is taken as the positive direction limiting heading angle for transmission line scattering spot adaptation imaging.

[0085] Based on the above embodiments, the coordinate positions of the mounting points at both ends of the transmission line are obtained. When the coordinates of the center point of the scattering spot Arrive at the mounting point on one side of the iron tower The time is the SAR satellite's limiting heading angle θ in the counterclockwise direction. m Coordinates of the center point of the scattering spot Arrive at the mounting point on one side of the iron tower At that time, the limiting value of the SAR satellite's heading angle θ on the other side can be obtained. n .

[0086] In step S103, when the horizontal rotating conductor extends in the same direction as the radar sensor’s flight direction, the geographical coordinates of the rotated transmission conductor are obtained by simulation. The center point of the transmission conductor’s scattering spot is located based on the center point localization method of the transmission conductor’s scattering spot in the above embodiment. The angle at which the center point of the transmission conductor’s scattering spot is located at the midpoint of the mounting points at both ends of the transmission conductor is taken as the optimal heading angle for the transmission conductor’s scattering spot to adapt to imaging.

[0087] Specifically, when the extension direction ξ of the transmission line is exactly the same as the heading angle θ of the satellite, the optimal heading angle is determined by finding that the center point of the SAR scattering spot of the transmission line is located between the two mounting points; when the extension direction of the transmission line is rotated to a suitable angle μ... k The optimal satellite heading angle is determined when the imaging position of the center point of the SAR scattering spot of the transmission line in the radar coordinate system is located at the midpoint between the two transmission line mounting points.

[0088] The following embodiments of this application use a power transmission line F as an example. Figure 8 The simulation function f for transmission lines in a certain area under different heading angles F (j a And the imaging center point under additional azimuth constraints. In this region, η = -4°, taking the gradient as 4°, we obtain μ. i The given values ​​are +10, +6, 0, -4, -10, -14, such that θ is -14, -10, 4, 0, 6, 10. (From...) Figure 8 As can be seen from point a, when the angle θ between the traverse and the flight heading angle is ±10°, the calculated spot patterns are not located on the traverse's three-dimensional point set. Therefore, under this angle condition, SAR cannot obtain an effective imaging center. Correspondingly, under TSX imagery of this region, the angle of the traverse scattering spot imaging should be close to η = +6 to -12°, corresponding to θ m =+10,θ n = -8°. Figure 8 As shown in b, when the angle η between the traverse and the flight heading angle is ±10°, the cluster spots calculated under CSK imagery are all on the traverse's three-dimensional point set, and SAR can obtain an effective imaging center. Therefore, under CSK imagery in this area, the angle between the traverse scattering spots should be close to η = +10° to -13°, corresponding to θ m =+14,θ n = -9°.

[0089] According to the method for determining the heading angle for transmission line scattering spot adaptation imaging proposed in the embodiments of this application, the extension direction of the transmission line is rotated relative to the target direction to simulate the imaging point set of the transmission line in the radar coordinate system, thereby locating the center point coordinates of the transmission line scattering spot. By calculating the coordinate positions of the mounting points at both ends and the coordinates of the center point of the transmission line scattering spot, the optimal value and limit range of the satellite heading angle can be determined. This method can simulate the position of the center point of the transmission line scattering spot under different heading angle conditions, and can also optimize the design of the flight path of the SAR sensor, including the flight path of the UAV and the orbital plane design of the satellite, by determining the optimal observation conditions.

[0090] Furthermore, this application embodiment also provides a device for locating the center point of a transmission line scattering spot. This device is applied to a sensor platform and includes: an acquisition module for acquiring the positioning deviation of synthetic aperture radar imagery; a calculation module for correcting the geometric positioning error of the transmission line imaging based on the positioning deviation, and calculating the radar imaging simulation formula of the transmission line based on the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the transmission line, and the range Doppler positioning model; and a positioning module for locating the center point of the transmission line scattering spot based on the radar imaging simulation formula.

[0091] This application embodiment also provides a heading angle determination device for transmission line scattering spot adaptation imaging. This device is applied to a data center or sensor scheduling platform and includes: a first determining module, used to horizontally rotate the extension direction of the transmission line clockwise, simulate the geographical coordinates of the rotated transmission line, locate the center point of the transmission line scattering spot based on the aforementioned transmission line scattering spot center point positioning device, and use the heading angle when the center point of the transmission line scattering spot is located at the transmission line mounting point as the negative direction limiting heading angle for transmission line scattering spot adaptation imaging; and a second determining module, used to horizontally rotate the extension direction of the transmission line counterclockwise, simulate the geographical coordinates of the rotated transmission line. The first module locates the center point of the transmission line scattering spot using the aforementioned center point positioning device, and uses the heading angle when the center point of the transmission line scattering spot is located at the transmission line mounting point as the positive direction limit heading angle for transmission line scattering spot adaptation imaging. The second module is used to simulate the geographical coordinates of the rotated transmission line when the horizontal rotating conductor's extension direction is consistent with the radar sensor's flight direction. Based on the aforementioned center point positioning device, the third module locates the center point of the transmission line scattering spot, and uses the angle when the center point of the transmission line scattering spot is located at the midpoint between the two mounting points of the transmission line as the optimal heading angle for transmission line scattering spot adaptation imaging.

[0092] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0093] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0094] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0095] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for locating the center point of a power transmission line scattering spot and determining the imaging heading angle, comprising: The method comprises the following steps: ​ Obtaining the positioning deviation of the synthetic aperture radar image; Correcting the geometric positioning error of the power transmission conductor imaging according to the positioning deviation, and calculating the radar imaging simulation formula of the power transmission conductor according to the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the power transmission conductor and the range-doppler positioning model; Positioning the center point of the power transmission conductor scattering spot according to the radar imaging simulation formula; Simulating the geographic coordinates of the rotated power transmission conductor by rotating the conductor extension direction horizontally clockwise, and taking the heading angle when the center point of the power transmission conductor scattering spot is located at the power transmission conductor mounting point as the negative direction limit heading angle of the power transmission conductor scattering spot adaptive imaging; Simulating the geographic coordinates of the rotated power transmission conductor by rotating the conductor extension direction horizontally counterclockwise, and taking the heading angle when the center point of the power transmission conductor scattering spot is located at the power transmission conductor mounting point as the positive direction limit heading angle of the power transmission conductor scattering spot adaptive imaging; When the horizontally rotated conductor extension direction is consistent with the flight direction of the radar sensor, simulating the geographic coordinates of the rotated power transmission conductor, and taking the angle when the center point of the power transmission conductor scattering spot is located at the intermediate position of the two end mounting points of the power transmission conductor as the best heading angle of the power transmission conductor scattering spot adaptive imaging.

2. The method of claim 1, wherein the center point of the power line scattering spot is located and the heading angle of the imaging is determined by, Obtaining the positioning deviation of the synthetic aperture radar image comprises: Obtaining the imaging parameters of the synthetic aperture radar image and the geographic coordinates of the ground control points in the synthetic aperture radar image; Calculating the geometric positioning coordinates of the geographic coordinates of the ground control points in the radar coordinate system by using the imaging parameters of the synthetic aperture radar image and the range-doppler positioning model; Determining the positioning deviation of the synthetic aperture radar image based on the radar scattering imaging center point coordinates of the ground control points and the geometric positioning coordinates, wherein the radar scattering imaging center point coordinates of the ground control points are the scattering intensity extreme point coordinates within the preset range of the ground control point target, and the positioning deviation of the radar image is used for correction of the geometric positioning of the synthetic aperture radar image.

3. The method of claim 1, wherein the center point of the power line scattering spot is located and the heading angle of the imaging is determined by, Calculating the radar imaging simulation result of the power transmission conductor according to the corrected geometric positioning error, the three-dimensional geographic coordinate point set of the power transmission conductor and the range-doppler positioning model comprises: Obtaining the radar imaging coordinate point set of the power transmission conductor in the radar coordinate system according to the three-dimensional geographic coordinate point set of the power transmission conductor, the corrected geometric positioning error and the range-doppler model; Obtaining the power transmission conductor radar imaging simulation formula by fitting method according to the radar imaging coordinate point set of the power transmission conductor, wherein the power transmission conductor radar imaging simulation formula is a parabolic function or a hyperbolic function.

4. The method of claim 3, wherein the center point of the scattering spot of the power transmission conductor is located and the heading angle of the imaging is determined by, Positioning the center point of the power transmission conductor scattering spot according to the radar imaging simulation formula comprises: Solving the position of the scattering spot center point according to the condition that the power transmission conductor radar imaging simulation formula and the scattering spot center point satisfy the azimuth parallel tangent equation condition or there exists a distance extreme point; When the power transmission conductor radar imaging simulation formula is a parabolic equation, the coordinate point position satisfying the azimuth parallel tangent equation condition is taken as the center point of the power transmission conductor scattering spot. When the radar imaging simulation formula of the power transmission conductor is a hyperbolic equation, a coordinate point satisfying the condition of the existence of the extreme point in the distance direction is used as the center point of the power transmission conductor scattering spot.

5. The method of claim 1, wherein the center point of the power line scattering spot is located and the heading angle of the imaging is determined by, The calculation method of the negative limit heading angle is as follows: The distance from the center point of the power transmission conductor scattering spot to the mounting points at the two ends of the power transmission conductor is calculated; When the distance from the center point of the power transmission conductor scattering spot to the mounting point at the end of the clockwise rotating conductor extension direction is zero, the heading angle is taken as the negative limit heading angle of the power transmission conductor scattering spot adaptive imaging.

6. The method of claim 1, wherein, The calculation method of the positive limit heading angle includes the following steps: The distance from the center point of the power transmission conductor scattering spot to the mounting points at the two ends of the power transmission conductor is calculated; When the distance from the center point of the power transmission conductor scattering spot to the mounting point at the end of the counterclockwise rotating conductor extension direction is zero, the heading angle is taken as the positive limit heading angle of the power transmission conductor scattering spot adaptive imaging.

7. The method of claim 1, wherein the center point of the power line scattering spot is located and the heading angle of the imaging is determined by, The calculation method of the optimal heading angle of the power transmission conductor scattering spot adaptive imaging is as follows: The angle offset of the power transmission conductor scattering spot adaptive imaging is determined according to the center point of the power transmission conductor scattering spot; The optimal heading angle is calculated according to the angle offset and the current angle of the power transmission conductor scattering spot adaptive imaging.

8. A device for locating the center of a power line scattering spot and determining the pointing angle of an imaging run, characterized by The device is applied to a sensor platform and includes: An acquisition module configured to acquire a positioning deviation of a synthetic aperture radar image; A calculation module configured to correct a geometric positioning error of power transmission conductor imaging according to the positioning deviation, and calculate a radar imaging simulation formula of the power transmission conductor according to the corrected geometric positioning error, a three-dimensional geographic coordinate point set of the power transmission conductor, and a range-Doppler positioning model; A positioning module configured to position a center point of a power transmission conductor scattering spot according to the radar imaging simulation formula; A first determination module configured to horizontally rotate a conductor extension direction clockwise, simulate geographic coordinates of the rotated power transmission conductor, and take a heading angle when the center point of the power transmission conductor scattering spot is located at a mounting point of the power transmission conductor as a negative limit heading angle of the power transmission conductor scattering spot adaptive imaging; A second determination module configured to horizontally rotate a conductor extension direction counterclockwise, simulate geographic coordinates of the rotated power transmission conductor, and take a heading angle when the center point of the power transmission conductor scattering spot is located at a mounting point of the power transmission conductor as a positive limit heading angle of the power transmission conductor scattering spot adaptive imaging; A third determination module configured to simulate geographic coordinates of the rotated power transmission conductor when a horizontally rotated conductor extension direction is consistent with a radar sensor flight direction, and take an angle when the center point of the power transmission conductor scattering spot is located at a middle position between the mounting points at the two ends of the power transmission conductor as an optimal heading angle of the power transmission conductor scattering spot adaptive imaging.

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