Urban outdoor monitoring camera rapid census device and method thereof

Abstract

The application discloses a city outdoor monitoring camera rapid survey device, comprising a marker and a camera management and data processing system, the camera management and data processing system is used for collecting and processing the marker information; the marker comprises a positioning device, a marker main body and a rotating device arranged in sequence from top to bottom, two chessboard calibration plates are arranged on the marker main body, and the marker is installed on a mobile carrier and moves in a city outdoor space. The application further discloses a city outdoor monitoring camera rapid survey method. The city outdoor monitoring camera rapid survey device and method disclosed by the application solve the problem that important parameters such as geographical space coordinates, a field angle and lens distortion are not recorded for the existing city outdoor monitoring camera.

Description

Technical Field

[0001] This invention belongs to the field of computer and video surveillance technology, specifically relating to a rapid survey device for urban outdoor surveillance cameras, and also to a rapid survey method for urban outdoor surveillance cameras. Background Technology

[0002] With the development of information technology, video surveillance technology has been widely applied in areas such as public security management, intelligent transportation, and disaster prevention. Surveillance cameras, as the most common real-time sensors in modern cities, are ubiquitous, drastically reducing major public safety incidents and significantly improving the social security index. Countries worldwide are vigorously promoting the application of video surveillance technology in public safety and urban management, with various video surveillance systems such as "Safe Cities" and "Skynet Project" flourishing, leading to a dramatic increase in urban outdoor surveillance cameras. It is estimated that there were 1 billion video surveillance cameras globally in 2021. However, during the construction of various urban outdoor surveillance systems, surveillance cameras are often procured in bulk and installed uniformly, generally lacking the recording of important information. This results in existing urban outdoor surveillance cameras lacking the recording of important parameters such as geospatial coordinates, field of view, and lens distortion, which poses difficulties for unified management and layout optimization of cameras, geospatial analysis of video data, and computer vision applications such as moving target trajectory tracking. Summary of the Invention

[0003] The purpose of this invention is to provide a rapid survey device for urban outdoor surveillance cameras, which solves the problem that existing urban outdoor surveillance cameras lack the recording of important parameters such as geographic spatial coordinates, field of view, and lens distortion.

[0004] Another objective of this invention is to provide a rapid survey method for urban outdoor surveillance cameras.

[0005] The technical solution adopted in this invention is a rapid survey device for urban outdoor surveillance cameras, including markers and a camera management and data processing system. The camera management and data processing system is used to collect and process marker information. The markers include a positioning device, a marker body, and a rotating device arranged sequentially from top to bottom. The marker body is provided with two checkerboard calibration plates. The markers are installed on a mobile carrier and move in the urban outdoor space.

[0006] The invention is further characterized by:

[0007] The positioning device includes a dual-antenna GNSS system, which consists of two GNSS receivers. The top of the marker is designed as a square structure, and the two GNSS receivers are installed at four equal points on the diagonal of the top of the marker to measure the position and attitude of the marker in geospatial space in real time. The main body of the marker is a smooth rectangular structure. Two checkerboard calibration plates are installed on two opposite sides of the main body. The remaining two sides and the top surface of the main body are painted in different colors to improve the marker's visibility in outdoor environments. The checkerboard calibration plates are... m OK n The column structure, the side length of each chessboard square on the chessboard grid marking board. b The checkerboard marking board has blank areas around the checkerboard grid. The upper end face of the rotating device is located at the bottom of the main body of the marker, and the lower end face of the rotating device is fixed to the moving carrier. The rotating device drives the main body of the marker to rotate around the center of the main body of the marker in a vertical direction, so that the posture of the two checkerboard calibration plates changes.

[0008] The camera management and data processing system is used for video data access, GNSS positioning data access, marker image recognition and screening, Zhang Zhengyou calibration, parameter calculation, and outdoor monitoring camera information management. The camera management and data processing system includes monitoring cameras, which are used to capture images of markers when they move through the camera's monitoring area, and obtain a monitoring image sequence containing a checkerboard calibration plate.

[0009] Another technical solution adopted in this invention is a rapid survey method for urban outdoor surveillance cameras, comprising the following steps: S1. Plan the movement trajectory of the landmark; S2. Make the marker move along the trajectory to obtain the geospatial location of the marker and surveillance video data containing the image of the marker; S3. By monitoring video data, obtain video frames containing the checkerboard calibration board; filter the video frames to obtain the calibration image; S4. Based on the calibration image, calibrate the parameters of the surveillance camera and obtain the intrinsic parameter matrix and extrinsic parameter matrix of the surveillance camera; S5. Solve for the geospatial transformation matrix based on the geospatial location of the landmark; S6. Solve for the geographical location of the surveillance cameras based on the geospatial transformation matrix; S7. Calculate the field of view of the surveillance camera.

[0010] Another feature of the technical solution adopted in this invention is that: S1 specifically refers to: S1.1 Ensure that all devices are working properly, keep the monitoring camera and positioning device synchronized in time, and accurately match the selected calibration image with the marker positioning data through the timestamp to obtain the accurate geographical location and movement posture of the marker when the image was captured. S1.2. Based on urban road traffic conditions, plan the movement trajectory of landmarks in the city.

[0011] S2 specifically refers to: S2.1. Use a mobile carrier to move the marker in the urban outdoor space. The two GNSS receivers on the top acquire the marker's positioning data in real time. When the marker passes through the monitoring area of ​​the monitoring camera, the monitoring camera captures the marker and obtains monitoring video data containing the marker's image. S2.2 Analyze GNSS positioning data to obtain the geospatial coordinates of two points on the top surface of the marker. , and the corresponding timestamp T pos Calculate the geographical location of the center of the top surface of the marker according to the formula. And the direction of movement of the marker, the direction of movement of the marker is a straight line. P 1 P 2 azimuth α ; ; S2.3 The monitoring video data includes video frame sequences and timestamps for each video frame. T img ,use T img and T pos Accurately match GNSS positioning data at the same time with monitoring images.

[0012] S3 specifically refers to: S3.1. Use computer vision methods or deep learning models to obtain video frames containing the chessboard calibration board from the surveillance video data; S3.2 From the video frames of the checkerboard calibration board, select images with clear marker imaging and complete checkerboard calibration board imaging according to the selection criteria; The selection criteria include clear imaging of the checkerboard calibration board, the checkerboard calibration board occupying more than 1 / 4 of the monitoring image, the checkerboard calibration board being distributed in the center and around the edges of the selected images, and the number of images being no less than 3.

[0013] S4 specifically refers to: S4.1 Implementation of Zhang Zhengyou calibration algorithm based on computer vision library OpenCV; S4.2, Filter the n The Zhang Zhengyou calibration algorithm inputs the calibration image to calibrate the surveillance camera, obtaining the intrinsic parameter matrix and extrinsic parameter matrix of the surveillance camera; the translation vector in the extrinsic parameter matrix is ​​the position coordinate of the surveillance camera in the Zhang Zhengyou calibration object coordinate system.

[0014] S5 specifically refers to: S5.1 Select at least 3 points on the marker; S5.2 Calculate the coordinates of the selected point in Zhang Zhengyou's calibrated object coordinate system; S5.3. Using the geographic spatial location of the geometric center of the top surface of the marker and the geometric relationships on the marker, calculate the coordinates of the selected point in the geographic spatial coordinate system; S5.4. Based on the coordinates of the selected point in Zhang Zhengyou's calibration object coordinate system and the coordinates of the selected point in the geographic space coordinate system, solve the transformation matrix between Zhang Zhengyou's calibration object coordinate system and the geographic space coordinate system through matrix singular value decomposition.

[0015] S6 specifically refers to: S6.1. By using the transformation matrix between Zhang Zhengyou's calibrated object coordinate system and the geographic space coordinate system, the coordinates of the surveillance camera in Zhang Zhengyou's calibrated object coordinate system are transformed to the geographic space coordinate system to obtain the geographic space coordinates of the camera. S6.2 In Zhang Zhengyou's calibration results, each calibration image has corresponding camera coordinates in Zhang Zhengyou's object coordinate system. The camera coordinates in Zhang Zhengyou's object coordinate system of each calibration image are converted into geospatial coordinates, and the average geospatial coordinates of the monitoring camera are calculated as the final geospatial position of the monitoring camera. When the mobile vehicle travels on the slope, the angle between the top surface of the marker and the horizontal plane is calculated and the coordinates are corrected. S7 specifically refers to: determining the known camera focal length using Zhang Zhengyou. f The physical dimensions of the camera image sensor are obtained from the calibration image information, respectively. h and v Calculate the horizontal field of view of the surveillance camera according to the formula. θ h and vertical field of view θv ; .

[0016] The beneficial effects of this invention are: The rapid survey device and method for urban outdoor surveillance cameras provided by this invention offer several advantages. First, it boasts high survey efficiency. By using a mobile carrier to move markers through urban outdoor spaces, it enables batch surveys and calibrations of a massive number of urban outdoor surveillance cameras. Compared to traditional camera calibration methods that require manual calibration of each camera individually, this invention significantly reduces workload and improves survey efficiency, making it suitable for large-scale urban applications. Second, it acquires comprehensive camera parameters, simultaneously obtaining the camera's 3D geospatial coordinates, field of view, and lens parameters (intrinsic parameter matrix, distortion coefficients), solving the problem of single parameter acquisition in existing methods and providing complete data support for subsequent applications. Finally, it is highly practical, applicable to different types of urban outdoor surveillance cameras (bullet type, dome type, hemispherical type, etc.), and can be applied to various scenarios such as unified camera management, layout optimization, video spatial analysis, and computer vision applications, providing technical support for related applications in smart cities, smart transportation, and urban management. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the rapid survey method for urban outdoor surveillance cameras according to the present invention. Figure 2 This is a schematic diagram of the structure of the marker of the present invention; Figure 3 This is a schematic diagram of Zhang Zhengyou's calibration of the object coordinate system according to the present invention; Figure 4 This is a schematic diagram of the posture of the marker of the present invention when the top surface is not parallel to the local horizontal plane. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0019] The present invention provides a rapid survey device for urban outdoor surveillance cameras, comprising markers and a camera management and data processing system. The camera management and data processing system is used to collect and process marker information. The markers include a positioning device, a marker body, and a rotating device arranged sequentially from top to bottom. The marker body is provided with two checkerboard calibration plates. The markers are mounted on a mobile carrier and move in urban outdoor space. The positioning device includes a dual-antenna GNSS system, which consists of two GNSS receivers. The top of the marker is designed as a square structure, and the two GNSS receivers are respectively installed at four equal points on the diagonal of the top of the marker, for real-time measurement of the marker's position and attitude in geographic space. The main body of the marker is a smooth rectangular structure. Two checkerboard calibration plates are installed on two opposite sides of the main body. The remaining two sides and the top surface of the main body are painted in different colors to improve the marker's visibility in outdoor environments. The checkerboard calibration plates are... m OKn The column structure, the side length of each chessboard square on the chessboard grid marking board. b The checkerboard marking board has blank areas around the checkerboard grid. The upper end face of the rotating device is located at the bottom of the marker body, and the lower end face of the rotating device is fixed to the moving carrier. The rotating device drives the marker body to rotate vertically around the center of the marker body, causing the posture of the two checkerboard calibration plates to change. The camera management and data processing system is used for video data access, GNSS positioning data access, marker image recognition and screening, Zhang Zhengyou calibration, parameter calculation, and outdoor monitoring camera information management. The camera management and data processing system includes a monitoring camera, which is used to capture images of the marker when it moves through the camera's monitoring area, obtaining a monitoring image sequence containing the checkerboard calibration plates.

[0020] Example 1 The rapid survey device for urban outdoor surveillance cameras proposed in this embodiment includes markers and a camera management and data processing system. The camera management and data processing system is used to collect and process marker information. The markers include a positioning device, a marker body, and a rotating device arranged sequentially from top to bottom. The marker body is provided with two checkerboard calibration plates. The markers are installed on a mobile carrier and move in the urban outdoor space.

[0021] Example 2 The rapid survey device for urban outdoor surveillance cameras proposed in this embodiment includes markers and a camera management and data processing system. The camera management and data processing system is used to collect and process marker information. The markers include a positioning device, a marker body, and a rotating device arranged sequentially from top to bottom. The marker body is equipped with two checkerboard calibration plates. The markers are mounted on a mobile carrier and move in the urban outdoor space. The positioning device includes a dual-antenna GNSS system, which consists of two GNSS receivers. The top of the marker is designed as a square structure, and the two GNSS receivers are respectively installed at four equal points on the diagonal of the top of the marker, for real-time measurement of the marker's position and attitude in geographic space. The main body of the marker is a smooth rectangular structure. Two checkerboard calibration plates are installed on two opposite sides of the main body. The remaining two sides and the top surface of the main body are painted in different colors to improve the marker's visibility in outdoor environments. The checkerboard calibration plates are... m OK n The column structure, the side length of each chessboard square on the chessboard grid marking board. b The checkerboard marking board has blank areas around the checkerboard grid. The upper end face of the rotating device is located at the bottom of the main body of the marker, and the lower end face of the rotating device is fixed to the moving carrier. The rotating device drives the main body of the marker to rotate around the center of the main body of the marker in a vertical direction, so that the posture of the two checkerboard calibration plates changes.

[0022] Example 3 The rapid survey device for urban outdoor surveillance cameras proposed in this embodiment includes markers and a camera management and data processing system. The camera management and data processing system is used to collect and process marker information. The markers include a positioning device, a marker body, and a rotating device arranged sequentially from top to bottom. The marker body has two checkerboard calibration plates. The markers are mounted on a mobile carrier and move in the urban outdoor space. The positioning device includes a dual-antenna GNSS system, which consists of two GNSS receivers. The GNSS receiver model is iRTK20, and the baseline length is [missing information]. The marker is designed with a square top, and two GNSS receivers are installed at four equal points on the diagonal of the top of the marker to measure the position and attitude of the marker in geospatial space in real time. The main body of the logo is a smooth rectangular prism structure, designed with one side length... The marker is a rectangular prism with two matte aluminum checkerboard calibration plates mounted on opposite sides of the main body. The remaining two sides and top of the marker are coated with different colors to improve its visibility in outdoor environments. These calibration plates are impact-resistant, durable, opaque, and non-reflective. Their excellent diffuse reflection treatment solves the problem of glare during application, allowing for better identification of calibration pattern details and achieving higher calibration and measurement accuracy. The calibration plate has an 8x11 grid, with each square having a side length of 0.1 meters. Blank spaces around the grid assist the computer in better recognizing the calibration plate. m OK n The column structure, the side length of each chessboard square on the chessboard grid marking board. b The checkerboard marking board has blank areas around the checkerboard grid. The upper end face of the rotating device is located at the bottom of the main body of the marker, and the lower end face of the rotating device is fixed to the mobile carrier. A car is used as the mobile carrier. The rotating device drives the main body of the marker to rotate around the center of the main body in a vertical direction, so that the posture of the two checkerboard calibration plates changes. The camera management and data processing system is used for video data access, GNSS positioning data access, marker image recognition and screening, Zhang Zhengyou calibration, parameter calculation and outdoor monitoring camera information management. The camera management and data processing system is developed based on the open source computer vision library OpenCV. The camera management and data processing system includes a monitoring camera. The monitoring camera is used to take pictures of the marker when the marker moves through the monitoring area of ​​the camera, and obtain a monitoring image sequence containing the checkerboard calibration plates.

[0023] Example 4 The rapid survey method for urban outdoor surveillance cameras proposed in this embodiment is based on the aforementioned rapid survey device for urban outdoor surveillance cameras, such as... Figure 1 As shown, it includes the following steps: S1. Plan the movement trajectory of the landmark; S2. Make the marker move along the trajectory to obtain the geospatial location of the marker and surveillance video data containing the image of the marker; S3. By monitoring video data, obtain video frames containing the checkerboard calibration board; filter the video frames to obtain the calibration image; S4. Based on the calibration image, calibrate the parameters of the surveillance camera and obtain the intrinsic parameter matrix and extrinsic parameter matrix of the surveillance camera; S5. Solve for the geospatial transformation matrix based on the geospatial location of the landmark; S6. Solve for the geographical location of the surveillance cameras based on the geospatial transformation matrix; S7. Calculate the field of view of the surveillance camera.

[0024] Example 5 The rapid survey method for urban outdoor surveillance cameras proposed in this embodiment is based on the aforementioned rapid survey device for urban outdoor surveillance cameras, such as... Figure 1 As shown, it includes the following steps: S1. Plan the movement trajectory of the landmark; Specifically: S1.1 Ensure that all devices are working properly, keep the monitoring camera and positioning device synchronized in time, and accurately match the selected calibration image with the marker positioning data through the timestamp to obtain the accurate geographical location and movement posture of the marker when the image was captured. S1.2. Based on urban road traffic conditions, plan the movement trajectory of the landmarks in the city; S2. Make the marker move along the trajectory to obtain the geospatial location of the marker and surveillance video data containing the image of the marker; Specifically: S2.1. Use a mobile carrier to move the marker in the urban outdoor space. The two GNSS receivers on the top acquire the marker's positioning data in real time. When the marker passes through the monitoring area of ​​the monitoring camera, the monitoring camera captures the marker and obtains monitoring video data containing the marker's image. S2.2 Analyze GNSS positioning data to obtain the geospatial coordinates of two points on the top surface of the marker. , and the corresponding timestamp T pos Calculate the geographical location of the center of the top surface of the marker according to the formula. And the direction of movement of the marker, the direction of movement of the marker is a straight line. P 1 P 2 azimuth α ; ; S2.3 The monitoring video data includes video frame sequences and timestamps for each video frame. T img ,use T img and T pos Accurately match GNSS positioning data with monitoring images at the same time; S3. By monitoring video data, obtain video frames containing the checkerboard calibration board; filter the video frames to obtain the calibration image; S4. Based on the calibration image, calibrate the parameters of the surveillance camera and obtain the intrinsic parameter matrix and extrinsic parameter matrix of the surveillance camera; S5. Solve for the geospatial transformation matrix based on the geospatial location of the landmark; S6. Solve for the geographical location of the surveillance cameras based on the geospatial transformation matrix; S7. Calculate the field of view of the surveillance camera.

[0025] Example 6 The rapid survey method for urban outdoor surveillance cameras proposed in this embodiment is based on the aforementioned rapid survey device for urban outdoor surveillance cameras, such as... Figure 1 As shown, it includes the following steps: S1. Plan the movement trajectory of the landmark; Specifically: S1.1 Ensure that all devices are working properly, keep the monitoring camera and positioning device synchronized in time, and accurately match the selected calibration image with the marker positioning data through the timestamp to obtain the accurate geographical location and movement posture of the marker when the image was captured. S1.2. Based on urban road traffic conditions, plan the movement trajectory of the landmarks in the city; S2. Make the marker move along the trajectory to obtain the geospatial location of the marker and surveillance video data containing the image of the marker; Specifically: S2.1. Use a mobile carrier to move the marker in the urban outdoor space. The two GNSS receivers on the top acquire the marker's positioning data in real time. When the marker passes through the monitoring area of ​​the monitoring camera, the monitoring camera captures the marker and obtains monitoring video data containing the marker's image. S2.2 Analyze GNSS positioning data to obtain the geospatial coordinates of two points on the top surface of the marker. , and the corresponding timestamp T pos Calculate the geographical location of the center of the top surface of the marker according to the formula. And the direction of movement of the marker, the direction of movement of the marker is a straight line. P 1 P 2 azimuth α ; ; S2.3 The monitoring video data includes video frame sequences and timestamps for each video frame. T img ,use T img and T pos Accurately match GNSS positioning data with monitoring images at the same time; S3. By monitoring video data, obtain video frames containing the checkerboard calibration board; filter the video frames to obtain the calibration image; Specifically: S3.1. Use computer vision methods or deep learning models to obtain video frames containing the chessboard calibration board from the surveillance video data; S3.2 From the video frames of the checkerboard calibration board, select images with clear marker imaging and complete checkerboard calibration board imaging according to the selection criteria; The selection criteria include clear imaging of the checkerboard calibration board, the checkerboard calibration board occupying more than 1 / 4 of the monitoring image, the checkerboard calibration board being distributed in the center and around the edges of the selected images, and the number of images being no less than 3. S4. Based on the calibration image, calibrate the parameters of the surveillance camera and obtain the intrinsic parameter matrix and extrinsic parameter matrix of the surveillance camera; Specifically: S4.1 Implementation of Zhang Zhengyou calibration algorithm based on computer vision library OpenCV; S4.2 Input the selected n calibration images into Zhang Zhengyou's calibration algorithm to calibrate the surveillance camera and obtain the intrinsic parameter matrix and extrinsic parameter matrix of the surveillance camera; the translation vector in the extrinsic parameter matrix is ​​the position coordinate of the surveillance camera in Zhang Zhengyou's calibration object coordinate system; S5. Solve for the geospatial transformation matrix based on the geospatial location of the landmark; S6. Solve for the geographical location of the surveillance cameras based on the geospatial transformation matrix; S7. Calculate the field of view of the surveillance camera.

[0026] Example 7 The rapid survey method for urban outdoor surveillance cameras proposed in this embodiment is based on the aforementioned rapid survey device for urban outdoor surveillance cameras, such as... Figure 1 As shown, it includes the following steps: S1. Plan the movement trajectory of the landmark; Specifically: S1.1 Ensure that all devices are working properly, keep the monitoring camera and positioning device synchronized in time, and accurately match the selected calibration image with the marker positioning data through the timestamp to obtain the accurate geographical location and movement posture of the marker when the image was captured. S1.2. Based on urban road traffic conditions, plan the movement trajectory of the landmarks in the city; S2. Make the marker move along the trajectory to obtain the geospatial location of the marker and surveillance video data containing the image of the marker; Specifically: S2.1. Use a mobile carrier to move the marker in the urban outdoor space. The two GNSS receivers on the top acquire the marker's positioning data in real time. When the marker passes through the monitoring area of ​​the monitoring camera, the monitoring camera captures the marker and obtains monitoring video data containing the marker's image. S2.2 Analyze GNSS positioning data to obtain the geospatial coordinates of two points on the top surface of the marker. , and the corresponding timestamp T pos Calculate the geographical location of the center of the top surface of the marker according to the formula. And the direction of movement of the marker, the direction of movement of the marker is a straight line. P 1 P 2 azimuth α ; ; S2.3 The monitoring video data includes video frame sequences and timestamps for each video frame. T img ,use T img and T pos Accurately match GNSS positioning data with monitoring images at the same time; S3. By monitoring video data, obtain video frames containing the checkerboard calibration board; filter the video frames to obtain the calibration image; Specifically: S3.1. Use computer vision methods or deep learning models to obtain video frames containing the chessboard calibration board from the surveillance video data; S3.2 From the video frames of the checkerboard calibration board, select images with clear marker imaging and complete checkerboard calibration board imaging according to the selection criteria; The selection criteria include clear imaging of the checkerboard calibration board, the checkerboard calibration board occupying more than 1 / 4 of the monitoring image, the checkerboard calibration board being distributed in the center and around the edges of the selected images, and the number of images being no less than 3. S4. Based on the calibration image, calibrate the parameters of the surveillance camera and obtain the intrinsic parameter matrix and extrinsic parameter matrix of the surveillance camera; Specifically: S4.1 Implementation of Zhang Zhengyou calibration algorithm based on computer vision library OpenCV; S4.2 Input the selected n calibration images into Zhang Zhengyou's calibration algorithm to calibrate the surveillance camera and obtain the intrinsic parameter matrix and extrinsic parameter matrix of the surveillance camera; the translation vector in the extrinsic parameter matrix is ​​the position coordinate of the surveillance camera in Zhang Zhengyou's calibration object coordinate system; S5. Solve for the geospatial transformation matrix based on the geospatial location of the landmark; Specifically: S5.1 Select at least 3 points on the marker; S5.2 Calculate the coordinates of the selected point in Zhang Zhengyou's calibrated object coordinate system; S5.3. Using the geographic spatial location of the geometric center of the top surface of the marker and the geometric relationships on the marker, calculate the coordinates of the selected point in the geographic spatial coordinate system; S5.4 Based on the coordinates of the selected point in Zhang Zhengyou's calibration object coordinate system and the coordinates of the selected point in the geographic space coordinate system, solve the transformation matrix between Zhang Zhengyou's calibration object coordinate system and the geographic space coordinate system through matrix singular value decomposition. S6. Solve for the geographical location of the surveillance cameras based on the geospatial transformation matrix; Specifically: S6.1. By using the transformation matrix between Zhang Zhengyou's calibrated object coordinate system and the geographic space coordinate system, the coordinates of the surveillance camera in Zhang Zhengyou's calibrated object coordinate system are transformed to the geographic space coordinate system to obtain the geographic space coordinates of the camera. S6.2 In Zhang Zhengyou's calibration results, each calibration image has corresponding camera coordinates in Zhang Zhengyou's object coordinate system. The camera coordinates in Zhang Zhengyou's object coordinate system of each calibration image are converted into geospatial coordinates, and the average geospatial coordinates of the monitoring camera are calculated as the final geospatial position of the monitoring camera. When the mobile vehicle travels on the slope, the angle between the top surface of the marker and the horizontal plane is calculated and the coordinates are corrected. S7. Calculate the field of view of the surveillance camera.

[0027] Specifically, this involves calibrating the known camera focal length using Zhang Zhengyou. f The physical dimensions of the camera image sensor are obtained from the calibration image information, respectively. h andv Calculate the horizontal field of view of the surveillance camera according to the formula. θ h and vertical field of view θv ; .

[0028] Example 8 The rapid survey method for urban outdoor surveillance cameras proposed in this embodiment is based on the aforementioned rapid survey device for urban outdoor surveillance cameras, such as... Figure 1 As shown, it includes the following steps: S1, approximately 2.5 km from a certain city 2 The area was designated as a pilot zone for the census, containing a total of 295 outdoor surveillance cameras. These included 94 traffic cameras, 106 residential area cameras, and 95 park cameras. The cameras included bullet cameras, dome cameras, and hemispherical cameras. Based on the accessibility of urban roads, residential areas, and park roads within the pilot zone, the approximate movement trajectories of the markers were planned. Experimental vehicles carrying the markers were then driven along the planned routes at a cruising speed of 15 km / h to obtain more accurate positioning information and clearer images of the markers. S2. Acquire the position and attitude data of the landmark during its movement in the urban outdoor space, as well as the surveillance video data containing the landmark; S2-1. Obtain GNSS positioning data of the marker during its movement in urban outdoor space; Among them, the two Hi-Target iRTK20 GNSS receivers installed on top of the marker will collect real-time location information according to the collection frequency during the movement of the marker, and obtain positioning data at different times; S2-2. Analyze the GNSS positioning data to obtain the geospatial location of the marker at each acquisition time during its movement in the urban outdoor space. and and the corresponding timestamp; The raw GNSS positioning data is in NMEA-0183 format. Parsing this message allows us to obtain the geographical location of the marker during its movement, and then calculate its direction of movement (azimuth). ); Suppose at a certain moment The corresponding video frames (images) are calibration images that meet the image selection criteria. Location data of time markers and For example, the calculation process is as follows: ; S2-3. When a marker moves through the camera's monitoring area in the urban outdoor environment, the camera captures monitoring video data containing the marker. S3. Identify landmarks from the surveillance video captured by the surveillance camera and select calibration images that meet Zhang Zhengyou's calibration requirements; This step specifically includes: S3-1. Using the marker recognition function in the data processing system, identify video frames (images) containing markers from the surveillance video and obtain the timestamp of the video frame. S3-2. Select images that meet the Zhang Zhengyou calibration requirements from video frame images containing markers. First, select multiple images with clear images of the calibration board, because in Zhang Zhengyou calibration, the clearer the image of the calibration board on the image, the more accurate the extraction of checkerboard corner points. Second, it is generally recommended that the calibration board occupy more than 1 / 4 of the entire image in Zhang Zhengyou calibration. When the calibration board occupies a larger area on the monitoring image, its image will usually be clearer. In addition, the position of the calibration board on the selected multiple images should be as even as possible. That is, in the selected multiple images, the calibration board should be distributed in the center and around the edges of the image as much as possible, so as to more accurately calibrate the camera lens distortion coefficient. S4. Camera parameter calibration: This will filter... Zhang's calibration image is input into the data processing system using Zhang Zhengyou's calibration algorithm to calculate the camera's intrinsic parameter matrix. and extrinsic parameter matrix

[0029] Where the intrinsic parameter matrix It is inherent to each camera, and the extrinsic parameter matrix is ​​related to the position and orientation of the calibration board during imaging. T is the position coordinate of the camera in the Zhang Zhengyou calibration object coordinate system. S5. Solve for the geospatial transformation matrix: Calculate the transformation relationship between Zhang Zhengyou's calibrated object coordinate system and the geospatial coordinate system; This step specifically includes: S5-1. Select at least 3 points on the marker, such as... Figure 3 As shown, there are four points: O, C, D, and E. S5-2. Calculate the coordinates of the four selected points in Zhang Zhengyou's calibration coordinate system. Zhang Zhengyou's calibration typically uses the first interior corner point at the top left corner of the calibration plate as the origin of the object coordinate system, and the plane of the calibration plate as the object coordinate system. Plane, such as Figure 2 As shown; therefore, the formulas for calculating the coordinates of the four selected points in Zhang Zhengyou's calibration coordinate system are as follows: ; S5-3. Calculate the coordinates of the four selected points in the geographic spatial coordinate system. The specific process includes: The side length of the square on the top surface of the sign Then the straight line length , The calibration board has a grid of 8 rows and 11 columns, and the side length of each square grid is... If the blank areas on the left, top, and right sides of the calibration board are all checkerboard grids, then the straight line... length Let the straight line be... With a straight line The included angle is Then the straight line azimuth of coordinates for: ; geospatial coordinates of points O and D and They are respectively: ; ; straight line length ,straight line With a straight line The lengths are equal, that is Let the straight line be... With a straight line The included angle is Then the straight line azimuth of coordinates Calculated using the following formula; ; Similarly, given points and straight line Length and its coordinate azimuth Then point and points geospatial coordinates and They can be calculated using the following formulas respectively; ; ; S5-4. Given the coordinates of four selected points in Zhang Zhengyou's calibrated object coordinate system and geographic space coordinate system, solve the transformation matrix between the two coordinate systems using singular value decomposition.

[0030] ; S5-5. Assume the top surface of the marker is parallel to the local horizontal plane (geographical coordinate system). (Surface), in reality, when vehicles or other mobile carriers go up or down a ramp, the top surface of the marker is no longer parallel to the local horizontal plane, such as Figure 4 As shown, the angle between the top surface of the marker and the local horizontal plane is... for: ; At this point, it is equivalent to the marker revolving around the geographic coordinate system. Axis rotation Angle, then point geospatial coordinates for: ; Then calculate the transformation matrix between Zhang Zhengyou's calibrated object coordinate system and geographic spatial coordinates. ; S6. Camera Geographic Location Determination: Assuming the calibration results from Zhang Zhengyou... Camera object coordinates at the time of calibration image Using the transformation matrix Convert it to a geospatial coordinate system to obtain This refers to the geospatial coordinates of the surveillance camera. The translation matrix in the camera extrinsic parameters of the calibration results homogeneous coordinates ; Repeating the above calculation process, and processing the n calibration images captured by the surveillance camera and Zhang Zhengyou's calibration results respectively, we can obtain n possible geospatial coordinates of the surveillance camera, and calculate the average value. As the final geospatial coordinates of the surveillance camera; S7. Calculate the camera's field of view (FOV). The camera's focal length has already been obtained through Zhang Zhengyou's calibration. The camera sensor size can be obtained from the image information. and Then the camera's horizontal field of view and vertical field of view The calculation formula is: ; Through the above steps, simulation verification was conducted on the selected census experimental area. Under the Windows 11 system environment, a camera management and data processing system was developed using C++. The rapid census device and method proposed in this invention were used to calibrate and survey the surveillance cameras in the experimental area. Due to tree obstruction or other reasons, the cameras were unable to capture calibration images. In the simulation experiment, lens information, geospatial location, and field of view of 269 surveillance cameras in the experimental area were obtained. Simultaneously, the geographical location of the surveillance cameras in the experimental area was measured using measurement methods. It can be seen that the rapid census method proposed in this invention can accurately obtain the location of urban outdoor surveillance cameras, and also obtain camera lens parameter information and field of view.

Claims

1. A rapid survey device for urban outdoor surveillance cameras, characterized in that, The system includes a marker and camera management and data processing system, which is used to collect and process marker information; the marker includes a positioning device, a marker body and a rotating device arranged from top to bottom, the marker body is provided with two checkerboard calibration plates, and the marker is installed on a mobile carrier to move in urban outdoor space.

2. The rapid survey device for urban outdoor surveillance cameras according to claim 1, characterized in that, The positioning device includes a dual-antenna GNSS system, which consists of two GNSS receivers. The top of the marker is designed as a square structure, and the two GNSS receivers are respectively installed at four equal points on the diagonal of the top of the marker, for real-time measurement of the marker's position and attitude in geographic space. The main body of the marker is a smooth rectangular structure. Two checkerboard calibration plates are installed on two opposite sides of the main body. The other two sides and the top surface of the main body are coated with different colors to improve the marker's visibility in outdoor environments. The checkerboard calibration plates are... m OK n The column structure, wherein the side length of each grid cell on the chessboard calibration plate is... b The checkerboard marking board has blank areas around the checkerboard grid. The upper end face of the rotating device is located at the bottom of the main body of the marker, and the lower end face of the rotating device is fixed to the moving carrier. The rotating device drives the main body of the marker to rotate around the center of the main body of the marker in a vertical direction, so that the posture of the two chessboard calibration plates changes.

3. The rapid survey device for urban outdoor surveillance cameras according to claim 2, characterized in that, The camera management and data processing system is used for video data access, GNSS positioning data access, marker image recognition and filtering, Zhang Zhengyou calibration, parameter calculation, and outdoor monitoring camera information management; the camera management and data processing system includes a monitoring camera, which is used to capture images of the marker when it moves through the camera's monitoring area, and obtain a monitoring image sequence containing a checkerboard calibration plate.

4. A rapid survey method for urban outdoor surveillance cameras, characterized in that, The rapid survey device for urban outdoor surveillance cameras according to claim 3 includes the following steps: S1. Plan the movement trajectory of the landmark; S2. Make the marker move along the trajectory to obtain the geospatial location of the marker and surveillance video data containing the image of the marker; S3. By monitoring video data, obtain video frames containing the checkerboard calibration board; filter the video frames to obtain the calibration image; S4. Based on the calibration image, calibrate the parameters of the surveillance camera and obtain the intrinsic parameter matrix and extrinsic parameter matrix of the surveillance camera; S5. Solve for the geospatial transformation matrix based on the geospatial location of the landmark; S6. Solve for the geographical location of the surveillance cameras based on the geospatial transformation matrix; S7. Calculate the field of view of the surveillance camera.

5. The rapid survey method for urban outdoor surveillance cameras according to claim 4, characterized in that, Specifically, S1 is: S1.1 Ensure that all devices are working properly, keep the monitoring camera and positioning device synchronized in time, and accurately match the selected calibration image with the marker positioning data through the timestamp to obtain the accurate geographical location and movement posture of the marker when the image was captured. S1.

2. Based on urban road traffic conditions, plan the movement trajectory of landmarks in the city.

6. The rapid survey method for urban outdoor surveillance cameras according to claim 5, characterized in that, Specifically, S2 is: S2.

1. Use a mobile carrier to move the marker in the urban outdoor space. The two GNSS receivers on the top acquire the marker's positioning data in real time. When the marker passes through the monitoring area of ​​the monitoring camera, the monitoring camera captures the marker and obtains monitoring video data containing the marker's image. S2.2 Analyze GNSS positioning data to obtain the geospatial coordinates of two points on the top surface of the marker. , and the corresponding timestamp T pos Calculate the geographical location of the center of the top surface of the marker according to the formula. And the direction of movement of the marker, the direction of movement of the marker is a straight line. P 1 P 2 azimuth coordinates α ; ； S2.3 The monitoring video data includes video frame sequences and timestamps for each video frame. T img ,use T img and T pos Accurately match GNSS positioning data at the same time with monitoring images.

7. The rapid survey method for urban outdoor surveillance cameras according to claim 6, characterized in that, Specifically, S3 is: S3.

1. Use computer vision methods or deep learning models to obtain video frames containing the chessboard calibration board from the surveillance video data; S3.2 From the video frames of the checkerboard calibration board, select images with clear marker imaging and complete checkerboard calibration board imaging according to the selection criteria; The selection criteria include clear imaging of the checkerboard calibration board, the checkerboard calibration board occupying more than 1 / 4 of the monitoring image, the checkerboard calibration board being distributed in the center and around the edges of the selected images, and the number of images being no less than 3.

8. The rapid survey method for urban outdoor surveillance cameras according to claim 7, characterized in that, Specifically, S4 is: S4.1 Implementation of Zhang Zhengyou calibration algorithm based on computer vision library OpenCV; S4.2 Input the selected n calibration images into Zhang Zhengyou's calibration algorithm to calibrate the surveillance camera and obtain the intrinsic parameter matrix and extrinsic parameter matrix of the surveillance camera; The translation vector in the extrinsic parameter matrix represents the position coordinates of the surveillance camera in the Zhang Zhengyou calibrated object coordinate system.

9. The rapid survey method for urban outdoor surveillance cameras according to claim 8, characterized in that, Specifically, S5 is: S5.1 Select at least 3 points on the marker; S5.2 Calculate the coordinates of the selected point in Zhang Zhengyou's calibrated object coordinate system; S5.

3. Using the geographic spatial location of the geometric center of the top surface of the marker and the geometric relationships on the marker, calculate the coordinates of the selected point in the geographic spatial coordinate system; S5.

4. Based on the coordinates of the selected point in Zhang Zhengyou's calibration object coordinate system and the coordinates of the selected point in the geographic space coordinate system, solve the transformation matrix between Zhang Zhengyou's calibration object coordinate system and the geographic space coordinate system through matrix singular value decomposition.

10. The rapid survey method for urban outdoor surveillance cameras according to claim 9, characterized in that, Specifically, S6 is: S6.

1. By using the transformation matrix between Zhang Zhengyou's calibrated object coordinate system and the geographic space coordinate system, the coordinates of the surveillance camera in Zhang Zhengyou's calibrated object coordinate system are transformed to the geographic space coordinate system to obtain the geographic space coordinates of the camera. S6.2 In Zhang Zhengyou's calibration results, each calibration image has corresponding camera coordinates in Zhang Zhengyou's object coordinate system. The camera coordinates in Zhang Zhengyou's object coordinate system of each calibration image are converted into geospatial coordinates, and the average geospatial coordinates of the monitoring camera are calculated as the final geospatial position of the monitoring camera. When the mobile vehicle travels on the slope, the angle between the top surface of the marker and the horizontal plane is calculated and the coordinates are corrected. Specifically, S7 involves: calibrating the known camera focal length using Zhang Zhengyou. f The physical dimensions of the camera image sensor are obtained from the calibration image information, respectively. h and v Calculate the horizontal field of view of the surveillance camera according to the formula. θ h and vertical field of view θv ; 。

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