Tower tilt online monitoring method based on remote sensing satellite optical image

Abstract

The present application relates to a kind of tower tilt online monitoring method based on remote sensing satellite optical image, comprising: step 1: obtain remote sensing satellite optical image, and carry out segmentation, obtain the image of tower shadow area;Step 2: with morphological method, the image of tower shadow area is enhanced and segmented, adopt a kind of adaptive variable structure element morphological edge detection operator, by Top-Hat transformation and Bottom-Hat transformation, remote sensing satellite optical image is high processing, then again using Canny operator carries out edge detection;Step 3: using Hough straight line detection algorithm extracts the straight line of tower shadow edge in tower shadow image, calculates the midpoint of the coordinates of contour line, obtains the geometric center line of contour.The step 4: establish the geometric relationship model of tower tilt and tower shadow;Step 5: based on step 4, calculate the inclination angle, according to inclination angle, judge tower tilt situation, and output result.

Description

Technical Field

[0001] This invention relates to the field of transmission line tower tilt fault monitoring technology, specifically a method for online monitoring of tower tilt based on remote sensing satellite optical imagery. Background Technology

[0002] Transmission towers are essential infrastructure for ensuring the operation of the power grid and serve as the support points for overhead transmission lines. They are susceptible to deformation and tilting due to extreme weather and uneven conductor stress. In severe cases, this can lead to safety accidents such as line breaks, power outages, and tower collapses, resulting in significant economic losses and safety hazards. Therefore, monitoring the tilt of transmission towers is of great importance for the protection of overhead transmission lines.

[0003] Currently, methods for monitoring power pole tilt mainly include manual inspection, online monitoring, robotic inspection, and drone inspection. Manual inspection involves workers carrying measuring instruments to conduct on-site measurements, which is labor-intensive, inefficient, and significantly affected by geographical conditions. Online monitoring involves installing cameras or sensors on the poles to monitor transmission lines in real time; however, this method is expensive to install initially, has high operating costs, and is difficult to maintain later. Line inspection robots can carry various sensors to detect defects in transmission lines, but this method is costly and has poor real-time performance. Drone aerial inspection has a low level of automation, heavily relies on operator skills, and has complex path planning. The development of satellite technology has provided new means for detecting transmission line faults and predicting the impact of natural disasters on the power grid. Compared with manual and aerial inspection, satellite inspection has advantages such as shorter cycle time, no safety hazards, wider inspection coverage, and faster response speed. Currently, satellite optical imagery has been studied in areas such as wildfires and floods, but research on power pole tilt is scarce. Summary of the Invention

[0004] Pole tilting is mostly caused by natural disasters or uneven conductor stress. In severe cases, it can lead to accidents such as line breaks, power outages, and tower collapses, resulting in huge economic losses and social impacts. Due to the Earth's rotation and the invariance of the relative position of the sun, the solar altitude angle changes throughout the day, and the shadows of objects also change. The shadows of objects are affected by the sun and themselves; when a pole tilts, the length and angle of the shadow also change. High-resolution remote sensing satellites offer wide observation range and high efficiency, providing new means for discovering potential faults in transmission lines and predicting natural disasters. This invention proposes an online monitoring method for pole tilting based on remote sensing satellite optical image data. This method uses morphological image processing and the Hough line detection algorithm to extract pole shadows, constructing a geometric relationship model between pole tilt and pole shadows to determine pole tilt. Monitoring potential pole tilting hazards based on satellite optical image data has advantages such as short inspection cycles, wide inspection coverage areas, fast calculation, and low cost.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention utilizes remote sensing satellite optical image data and employs morphological image processing methods and Hough transform line detection algorithms to establish a geometric relationship model between tower tilt and tower shadow. It proposes an online monitoring method for tower tilt based on remote sensing satellite optical imagery, and uses this method to monitor and identify potential tower tilt faults.

[0007] The method for online monitoring of tower tilt based on remote sensing satellite optical imagery includes the following steps:

[0008] Step 1: Acquire remote sensing satellite optical images, preprocess the remote sensing satellite optical images, and then segment the preprocessed remote sensing satellite optical images to obtain images of the tower shadow areas;

[0009] Step 2: Enhance the image of the tower shadow area obtained in Step 1 using morphological methods. Employ an adaptive variable structuring element morphological edge detection operator, and perform high-pass filtering on the image of the tower shadow area through Top-Hat transform and Bottom-Hat transform to highlight shadow details. Then, use the Canny operator for edge detection to obtain the tower shadow image.

[0010] Step 3: Use the Hough line detection algorithm to extract the straight lines of the pole shadow edge in the pole shadow image. Find the outline of the pole shadow by comparing the coordinates of the endpoints of the straight lines, calculate the midpoint of the coordinates above and below the outline, and obtain the geometric center line of the outline.

[0011] Step 4: Establish a geometric model of the relationship between the tower tilt and the tower shadow;

[0012] Step 5: Based on the geometric relationship model between tower tilt and tower shadow, calculate the tilt angle and determine the tower tilt status based on the tilt angle;

[0013] Step 6: Output tower tilt status.

[0014] Based on the above scheme, the preprocessing in step 1 includes: radiometric calibration, atmospheric correction and orthorectification, etc.

[0015] Based on the above scheme, step 2 specifically includes:

[0016] Step 21: Define two different structural elements, and use the two different structural elements b j For j=1,2, cross operations are performed. The size of structuring element b1 is 3×3, and the size of structuring element b2 is 5×5, as shown in formula (1) and formula (2) respectively:

[0017]

[0018] Decompose b2 into b in eight directions. 2i i = 1, 2, 3... 8, and the angles of each decomposition structure element differ by 22.5°;

[0019] A morphological edge detection operator is constructed using structuring elements, and the morphological edge detection operator is expressed as follows:

[0020]

[0021] Among them, G i Here, f is the morphological edge detection operator, and f is the original image from the remote sensing satellite optical image. For dilation, Θ is the erosion operation, and · is the closing operation. This is an opening operation;

[0022] Step 22: Preprocess the image of the tower shadow region using the morphological edge detection operator constructed in Step 21. Then, apply a Top-Hat transform to the preprocessed image of the tower shadow region using a high-pass filter, and finally use a Bottom-Hat transform to highlight the details of the darker tower shadows in the image, resulting in an enhanced image. The specific calculation formula is as follows:

[0023]

[0024] B i =(f·b 2i )-f (5)

[0025] F i =f+T i +Bi (6)

[0026]

[0027] Among them, T i For the image after Top-Hat transformation, B i The image after Bottom-Hat transformation; F i These are target images from different orientations; F represents the enhanced image.

[0028] Step 23: Apply the Canny operator to the enhanced image for edge detection to obtain the tower shadow image.

[0029] Based on the above scheme, step 3 specifically includes:

[0030] Step 31: Use the Hough transform line detection algorithm to extract the straight lines at the edges of the tower shadows in the tower shadow image, and define the mapping relationship as:

[0031]

[0032] Where (x,y) are the coordinates of a point on the tower's shadow image, and θ H Polar angle, ρ is the polar radius;

[0033] Step 32: Use the MATLAB functions hough(), houghpeaks(), and houghlines() to obtain the Hough matrix and find the peak points of the matrix. Then, extract the straight lines in the tower shadow image obtained in Step 2, so as to construct the tower shadow outline based on the extracted straight lines.

[0034] Based on the above scheme, step 4 specifically includes:

[0035] Step 41: Assume that the Earth is a perfect sphere, and the sunlight hitting the Earth is parallel. The length of an object's shadow is affected by the solar altitude angle and the object's own height. The solar altitude angle is affected by parameters such as latitude and longitude and time.

[0036] The length S of the object's shadow is expressed as:

[0037] S=Hcotα (9)

[0038] sinα=sinω×sinδ+cosω×cosδ×cost (10)

[0039] Where α is the solar altitude angle, H is the height of the object, S is the length of the object's shadow, ω is the geographical latitude, δ is the solar declination, and t is the hour angle;

[0040] The formula for calculating the solar declination δ is:

[0041]

[0042] b = 2πn / 365 (12)

[0043] t=(T1-12)×15° (13)

[0044] Where b is the solar angle, n is the date number, and T1 is the true solar time.

[0045] Step 42: The formula for calculating the solar azimuth angle is:

[0046] cosβ=(sinα×sinω-sinδ)÷(cosα×sinω) (14)

[0047] Wherein, the solar azimuth angle is β, α is the solar altitude angle, ω is the geographic latitude, and δ is the solar declination.

[0048] Step 43: Establish a geometric model of the relationship between tower tilt and tower shadow:

[0049] The upper end point of the tower is denoted as A, and the lower end point is denoted as O. A spherical coordinate system is established with the lower end point O of the tower as the center. The X-axis is the direction due east of the plane where the ground is located, the Y-axis is the direction due south of the plane where the ground is located, and the direction perpendicular to the ground is the Z-axis.

[0050] Let AB be the sunlight passing through the upper end point A of the tower, OB be the shadow of the tower on the xoy plane, H be the foot of the perpendicular from the upper end point A of the tower to the xoy plane, and BH be the projection of the sunlight on the xoy plane. Extend BH to intersect the X-axis, and let K be the point where the X-axis intersects. This gives us HK.

[0051] Based on the solar altitude angle α, solar azimuth angle β, tower length OA l, tower shadow length OB l0, and the angle between the tower shadow and the X-axis... Solve for the angle between the projection OH of the tower OA on the xoy plane and the X-axis. The angle θ between the tower OA and the Z-axis;

[0052] Represent the coordinates of the upper endpoint A and the lower endpoint B of the tower using known quantities, where the coordinates of point A are expressed as: The coordinates of point B are represented as follows: Then the vector AB is:

[0053]

[0054] The projection of vector AB onto the xoy plane is:

[0055]

[0056] According to the definitions of solar altitude angle and solar azimuth angle, we have:

[0057]

[0058] Substituting equations (15) and (16) into equation (17), we get:

[0059]

[0060] Solving equations (18) and (19) yields the angle between the projection OH of the tower OA onto the xoy plane and the X-axis. The angle θ between tower OA and the Z-axis is the tilt angle.

[0061] Based on the above scheme, step 5 specifically includes:

[0062] Based on the geometric model of tower tilt and tower shadow obtained in step 4, calculate the tower tilt angle. When the tower tilt angle is distributed in [0°-45°], it is considered tilted. When the tower tilt angle is distributed in [45°-90°], it is considered an invalid solution or the tower has collapsed.

[0063] Based on the above scheme, and considering satellite resolution and image extraction errors, a tower tilt angle threshold is set, which is θ. max =10°. When the tower tilt angle is distributed in the range of [0°-45°) and is greater than the tower tilt angle threshold, the tower is determined to be tilted.

[0064] The beneficial effects of this invention are:

[0065] 1. Based on remote sensing satellite optical imagery, the outline of the tower shadow is obtained through image enhancement processing, edge detection, and Hough line detection algorithms. According to the established geometric relationship model between tower tilt and tower shadow, the tower tilt angle is calculated, and the tower tilt situation is judged.

[0066] 2. Experimental verification shows that the error in satellite image processing is within 6.474%; calculations and judgments on actual extracted samples all yielded correct results; and the accuracy rate for judging simulated samples was 87.5%.

[0067] 3. Compared with traditional inspection methods, the method provided in this application has advantages such as shorter cycle, wider inspection coverage area, and lower cost. Attached Figure Description

[0068] The present invention includes the following figures:

[0069] Figure 1 Flowchart of an online monitoring method for tower tilt based on remote sensing satellite optical imagery

[0070] Figure 2 Schematic diagram of shadow imaging principle

[0071] Figure 3 Schematic diagram of the geometric relationship between tower tilt and tower shadow.

[0072] Figure 4 Diagram for determining tilt based on included angle Detailed Implementation

[0073] The following is in conjunction with the appendix Figures 1-4 The present invention will be described in further detail below.

[0074] Figure 1 The flowchart illustrates the online monitoring method for pole tilt based on remote sensing satellite optical imagery. The specific implementation of this invention, employing techniques such as morphological enhancement processing, Hough transform line detection, geometric models of pole tilt and pole shadows, and pole tilt discrimination criteria, is as follows:

[0075] Step 1: Acquire remote sensing satellite optical images, preprocess the remote sensing satellite optical images, and then segment the preprocessed remote sensing satellite optical images to obtain images of the tower shadow areas;

[0076] Step 2 uses morphological methods to enhance the image of the tower shadow area obtained in Step 1. An adaptive variable structuring element morphological edge detection operator is used. The image of the tower shadow area is high-pass filtered by Top-Hat transform and Bottom-Hat transform to highlight shadow details. Then, the Canny operator is used for edge detection to obtain the tower shadow image.

[0077] Step 21: Define two different structural elements, and use the two different structural elements b j For j=1,2, cross operations are performed. The size of structuring element b1 is 3×3, and the size of structuring element b2 is 5×5, as shown in formula (1) and formula (2) respectively:

[0078]

[0079] Decompose b2 into b in eight directions. 2i i = 1, 2, 3... 8, and the angles of each decomposition structure element differ by 22.5°;

[0080] A morphological edge detection operator is constructed using structuring elements, and the morphological edge detection operator is expressed as follows:

[0081]

[0082] Among them, G iHere, f is the morphological edge detection operator, and f is the original image from the remote sensing satellite optical image. For dilation, Θ is for erosion, and g is for closing. This is an opening operation;

[0083] Step 22: Preprocess the image of the tower shadow region using the morphological edge detection operator constructed in Step 21. Then, apply a Top-Hat transform to the preprocessed image of the tower shadow region using a high-pass filter, and finally use a Bottom-Hat transform to highlight the details of the darker tower shadows in the image, resulting in an enhanced image. The specific calculation formula is as follows:

[0084]

[0085] B i =(f·b 2i )-f (5)

[0086] F i =f+T i +B i (6)

[0087]

[0088] Among them, T i For the image after Top-Hat transformation, B i The image after Bottom-Hat transformation; F i These are target images from different orientations; F represents the enhanced image.

[0089] Through steps 11 to 12 above, we can remove noise and background information interference, effectively preserve effective edge information, and extract darker details in the image, thus achieving image enhancement.

[0090] Step 23: Apply the Canny operator to the enhanced image for edge detection to obtain the tower shadow image.

[0091] Step 3: Use Hough transform to detect the straight line at the edge of the tower shadow in the tower shadow image. Find the outline of the tower shadow by comparing the coordinates of the endpoints of the straight line. Calculate the midpoint of the coordinates above and below the outline to obtain the geometric center line of the outline. The length of the geometric center line is the length of the tower shadow.

[0092] Step 31: Use the Hough transform line detection algorithm to extract the straight lines at the edges of the tower shadows in the tower shadow image, and define the mapping relationship as:

[0093]

[0094] Where (x,y) are the coordinates of a point on the tower's shadow image, and θ H Polar angle, ρ is the polar radius;

[0095] Step 32: Use the MATLAB functions hough(), houghpeaks(), and houghlines() to obtain the Hough matrix and find the peak points of the matrix. Then, extract the straight lines in the tower shadow image obtained in step 1, so as to construct the tower shadow outline based on the extracted straight lines.

[0096] Step 4: Establish a geometric model of the relationship between tower tilt and tower shadow.

[0097] Step 41: Due to the Earth's rotation and the invariance of the relative position of the Sun, the solar altitude angle changes throughout the day, thus changing the shadows of objects. Assuming the Earth is a perfect sphere and the sunlight reaching the Earth is parallel, the length of an object's shadow is affected by both the solar altitude angle and the object's height. The imaging principle is as follows: Figure 2 As shown, the solar altitude angle is affected by parameters such as latitude and longitude, and time.

[0098] The length S of the object's shadow is represented as:

[0099] S=Hcotα (9)

[0100] sinα=sinω×sinδ+cosω×cosδ×cost (10)

[0101] Where α is the solar altitude angle, H is the height of the object, S is the length of the object's shadow, ω is the geographical latitude, δ is the solar declination, and t is the hour angle;

[0102] The formula for calculating the solar declination δ is:

[0103]

[0104] b = 2πn / 365 (12)

[0105] t=(T1-12)×15° (13)

[0106] Where b is the solar angle, n is the date number, based on the actual date of each year. For example, in 2021, January 1st is n=1, September 30th is n=273, and T1 is true solar time.

[0107] Since satellite images generally cannot reach 90°, let the satellite's altitude angle be α0. If the direction of sunlight is the same as the direction of satellite imaging, the entire shadow cannot be seen. At this time, the imaged part of the object's shadow is L2, where L2 = S - L1. If the direction of sunlight is opposite to the direction of satellite imaging, the entire shadow of the object can be seen. The length of the object's shadow is shown in equation (9).

[0108] Step 42: The formula for calculating the solar azimuth angle is:

[0109] cosβ=(sinα×sinω-sinδ)÷(cosα×sinω) (14)

[0110] Wherein, the solar azimuth angle is β, α is the solar altitude angle, ω is the geographic latitude, and δ is the solar declination.

[0111] The preprocessing of remote sensing images includes radiometric calibration, atmospheric correction, and orthorectification. It can be assumed that the solar azimuth angle is equal to the satellite azimuth angle. When the direction of solar illumination is opposite to the direction of satellite imaging, the image of the tower apex on the image has no effect on the shadow. When the satellite image is an orthographic image, it is assumed that the image of the tower apex on the image coincides with the tower origin. Therefore, when calculating the shadow, only the solar altitude angle needs to be considered.

[0112] Step 43: Based on the above theoretical knowledge, establish a geometric relationship model between the tower tilt and the tower shadow, such as... Figure 3 As shown:

[0113] The upper end point of the tower is denoted as A, and the lower end point is denoted as O. A spherical coordinate system is established with the lower end point O of the tower as the center. The X-axis is the direction due east of the plane where the ground is located, the Y-axis is the direction due south of the plane where the ground is located, and the direction perpendicular to the ground is the Z-axis.

[0114] Let AB be the sunlight passing through the upper end point A of the tower, OB be the shadow of the tower on the xoy plane, H be the foot of the perpendicular from the upper end point A of the tower to the xoy plane, and BH be the projection of the sunlight on the xoy plane. Extend BH to intersect the X-axis, and let K be the point where the X-axis intersects. This gives us HK.

[0115] Based on the known solar altitude angle α, solar azimuth angle β, tower length OA l, tower shadow length OB l0, and the angle between the tower shadow and the X-axis... Solve for the angle between the projection OH of the tower OA on the xoy plane and the X-axis. The angle θ between the tower OA and the Z-axis;

[0116] Represent the coordinates of the upper endpoint A and the lower endpoint B of the tower using known quantities, where the coordinates of point A are expressed as: The coordinates of point B are represented as follows: Then the vector AB is:

[0117]

[0118] The projection of vector AB onto the xoy plane is:

[0119]

[0120] According to the definitions of solar altitude angle and solar azimuth angle, we have:

[0121]

[0122] Substituting equations (15) and (16) into equation (17), we get:

[0123]

[0124] Solving equations (18) and (19) yields the angle between the projection OH of the tower OA onto the xoy plane and the X-axis. The angle θ between tower OA and the Z-axis is the tilt angle.

[0125] Step 5: Based on the geometric relationship model between tower tilt and tower shadow, calculate the tilt angle and determine the tower tilt situation.

[0126] Based on the geometric model of tower tilt and tower shadow, the tower tilt angle is calculated. As can be seen from the model, the solution is the point of tangency or intersection of a plane and a sphere. Therefore, there will be 1-4 solution values ​​that meet the requirements. Usually, 1-2 solution values ​​are distributed between 0° and 45°, and the rest are distributed between 45° and 90°. Based on our experience, we consider the values ​​distributed between 0° and 45° as the tilt angle, and the values ​​between 45° and 90° as invalid solutions or solutions that have already collapsed.

[0127] The angle θ between the projection OH and the Z-axis is the main basis for determining the tower's tilt. In the spherical coordinate system, the angle θ between the projection OH and the X-axis is... This is to determine the location of the tower and, when the tower tilts, to determine the direction of tilt. If shadows are extracted from satellite images, and a geometric relationship model between the tower tilt and its shadow is used, the angle θ between the tower and the vertical direction can be calculated. If the angle θ is greater than a set threshold, it can be determined that the tower is tilted. Considering satellite resolution and image extraction errors, the threshold is set to θ. max =10°.

[0128] Take actual remote sensing satellite images, and perform image processing on the shadowed areas of poles in the remote sensing satellite images. The processing procedure is in accordance with the attached... Figure 1The steps were carried out, and six towers were selected for experimental verification. The geometric model of tower tilt and tower shadow was calculated using the shadow data after image processing. The tilt of the experimental sample was obtained and compared with the actual situation. The results were all correct.

[0129] Since data on the shadow status of tilted towers in satellite imagery was lacking, a simulation was performed. The shadows of towers that were not tilted were selected and their length and angle were stretched. The data were then used to perform model calculations, and the accuracy rate of the results was 87.5%.

[0130] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A method for online monitoring of tower tilt based on remote sensing satellite optical images, characterized in that, The method comprises the following steps: Step 1: obtaining a remote sensing satellite optical image, pre-processing the remote sensing satellite optical image, and then segmenting the pre-processed remote sensing satellite optical image to obtain a tower shadow region image; Step 2: enhancing the tower shadow region image obtained in step 1 by using a morphological method, adopting a morphological edge detection operator with an adaptive variable structure element, performing high-pass filtering on the tower shadow region image through Top-Hat transformation and Bottom-Hat transformation to highlight the details of the shadow, and then performing edge detection on the enhanced image by using a Canny operator to obtain a tower shadow image; Step 3: extracting a straight line of the tower shadow edge in the tower shadow image by using a Hough straight line detection algorithm, finding a contour line of the tower shadow by comparing end point coordinates of the straight line, and calculating a midpoint of the contour line to obtain a geometric center line of the contour; Step 4: establishing a geometric relationship model of tower inclination and tower shadow; Step 5: calculating an inclination angle based on the geometric relationship model of tower inclination and tower shadow, and judging a tower inclination condition according to the inclination angle; Step 6: outputting the tower inclination condition.

2. The method for tower tilt online monitoring based on remote sensing satellite optical image according to claim 1, characterized in that, The pre-processing in step 1 comprises radiation calibration, atmospheric correction and orthographic correction.

3. The method for tower tilt online monitoring based on remote sensing satellite optical image according to claim 1, characterized in that, Step 2 specifically comprises: Step 21: define two different structuring elements, utilize two different structuring elements b j , j = 1, 2, the size of structuring element b1 is 3 x 3, the size of structuring element b2 is 5 x 5, as shown in formula (1) and formula (2) respectively: ; ; will be described below. In eight orientations, the decomposition is into each decomposition structuring element angle differs by 22.5°; A morphological edge detection operator is constructed using a structuring element, denoted as: ; wherein, is a morphological edge detection operator, is a raw image of an optical image of a remote sensing satellite, is a dilation operation, is an erosion operation, is a closing operation, is an opening operation; Step 22: pre-processing the tower shadow region image by using the morphological edge detection operator constructed in step 21, performing high-pass filtering on the pre-processed tower shadow region image by using Top-Hat transformation, highlighting details of the tower shadow in the image by using Bottom-Hat transformation, and obtaining an enhanced image, with a specific operation formula being: ; ; ; ; wherein, is a Top-Hat transformed image, is a Bottom-Hat transformed image; is a target image under a different direction, is an enhanced image; Step 23: performing edge detection on the enhanced image by using a Canny operator to obtain a tower shadow image.

4. The method for tower tilt online monitoring based on remote sensing satellite optical image of claim 3, wherein, Step 3 specifically comprises: Step 31: extracting a straight line of the tower shadow edge in the tower shadow image by using a Hough transformation straight line detection algorithm, and defining a mapping relationship as: ; wherein, is a point coordinate on the tower shadow image, is a polar angle, is a polar radius; Step 32: obtaining a Hough matrix and finding peak points of the matrix by using functions hough(), houghpeaks() and houghlines() in MATLAB, then extracting a straight line in the tower shadow in the tower shadow image obtained in step 2, and constructing a tower shadow contour according to the extracted straight line.

5. The method for tower tilt online monitoring based on remote sensing satellite optical image according to claim 4, characterized in that, Step 4 specifically comprises: Step 41: assuming that the earth is a regular sphere and the sunlight falling on the earth is parallel light, the shadow length of an object is affected by a solar elevation angle and an object height, and the solar elevation angle is affected by latitude, longitude and time parameters; the length of the object's shadow is represented as: ; ; wherein, is the solar elevation angle, is the height of the object, is the length of the object's shadow, is the geographic latitude, is the solar declination, is the hour angle; The solar declination The formula for calculating the solar declination is: ; ; ; wherein, is the solar noon, is the date number, is the true solar time; Step 42: a calculation formula of a solar azimuth angle is: ; wherein the solar azimuth is is the solar elevation angle, is the geographic latitude, is the solar declination; Step 43: establishing a geometric relationship model of tower inclination and tower shadow: an upper end point of the tower is denoted as A and a lower end point of the tower is denoted as O, a spherical coordinate system is established with the lower end point O of the tower as a center, wherein a positive east direction of a ground plane is an X axis, a positive south direction of the ground plane is a Y axis, and a direction perpendicular to the ground is a Z axis; The sunlight ray passing through the upper end point A of the pole tower is denoted as AB, the shadow of the pole tower in the xoy plane is denoted as OB, the foot of the upper end point A of the pole tower to the xoy plane is denoted as H, the projection of the sunlight ray in the xoy plane is denoted as BH, BH is extended to intersect the X axis, and the point intersecting the X axis is denoted as K, and HK is obtained; According to the solar elevation angle , the solar azimuth angle , the length of the tower OA , the length of the tower shadow OB , and the angle between the tower shadow and the X axis , the angle between the projection OH of the tower OA on the xoy plane and the X axis and the angle between the tower OA and the Z axis are solved. The coordinates of the upper end point A of the tower and the lower end point B of the tower are expressed by known quantities, wherein the coordinates of the point A are expressed as: ; the coordinates of the point B are expressed as: ; and the AB vector is: ; The projection of the AB vector in the xoy plane is: ; According to the definitions of the solar elevation angle and the solar azimuth angle, we have: ; Substituting formula (15) and formula (16) into formula (17), we have: ; ; Solving equations (18) and (19) gives the angle between the projection OH of the tower OA in the xoy plane and the X axis , and the angle between the tower OA and the Z axis , where the angle between the tower OA and the Z axis is the tilt angle.

6. The method for tower tilt online monitoring based on remote sensing satellite optical image of claim 5, wherein, Step 5 specifically includes: According to the geometric relation model of the tower tilt obtained in step 4 and the tower shadow, the tower tilt angle is calculated, and when the tower tilt angle is distributed in is regarded as invalid solution or tower collapse has occurred. is regarded as invalid solution or tower collapse has occurred.

7. The method for tower tilt online monitoring based on remote sensing satellite optical image according to claim 6, characterized in that, Considering the satellite resolution and the error of image extraction, a tower tilt angle threshold is set, which is When the tower tilt angle is distributed in and is greater than the tower tilt angle threshold, it is determined that the tower has tilted.

Images