CN110702343B - Deflection measurement system and method based on stereoscopic vision - Google Patents
Deflection measurement system and method based on stereoscopic vision Download PDFInfo
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Abstract
The invention discloses a deflection measuring system based on stereoscopic vision, which comprises an image acquisition module, a distance and angle measuring module, a control module and a data processing module, wherein the control module controls the image acquisition module and the distance and angle measuring module to respectively acquire data, the image acquisition module and the distance and angle measuring module respectively transmit the acquired data to the data processing module in real time, the data processing module reconstructs three-dimensional geometric information of a measured target by utilizing a parallax principle, and the deflection value of each measured point is obtained by calculating the space coordinate change of each measured target point on an adjacent interval image frame. The invention also discloses a deflection measuring method based on stereoscopic vision. The invention adopts a double-measuring-station mode, the two measuring stations are independent and have the same structural configuration, so that the invention can be used for both close-range measurement and long-distance large-field measurement, and simultaneously, the image enhancement algorithm is adopted to remove the influence of uneven illumination and haze, thereby improving the deflection measurement precision and better meeting the actual requirements of engineering detection.
Description
Technical Field
The invention relates to the technical field of detection and monitoring of large facility engineering structures such as bridges, in particular to a deflection measuring system and method based on stereoscopic vision.
Background
With the development of national infrastructure construction, large-scale facilities such as bridges and tunnels of different types are continuously emerged, the deflection is used as an important index for evaluating the safety and the service life of the large-scale facility structure, and the deflection measurement becomes an important work for evaluating the health and the safety of the large-scale facility structure.
The traditional deflection measurement usually adopts a contact type displacement sensor, a dial indicator and the like, the method is low in cost and simple in structure, but the problems of time and labor waste, incapability of being installed and real-time measurement under the conditions of crossing rivers, canyons and the like exist. Optical surveying and mapping instruments such as a total station and a theodolite can provide higher measuring accuracy, but the detection range is limited, only point-by-point measurement can be realized, the detection in a whole field and a large range cannot be realized, and the working efficiency is low. In recent years, an image measuring method becomes a hotspot of research on a large-scale facility deflection non-contact measuring technology, but most of the image measuring methods adopt a monocular vision image measuring method, the dimension measurement of a target object needs to be realized by taking an object with a known dimension in a scene as a reference object, the image measuring method is not suitable for occasions where the reference object cannot be placed, and the practical application has certain limitation; in addition, only a single camera is used for compressing the image acquired by the three-dimensional space to a two-dimensional plane, and when the target surface of the camera is not parallel to the measured surface, the measurement accuracy of the camera is greatly influenced.
In conclusion, a non-contact, high-precision, large-view-field, multi-point and three-dimensional real-time deflection measuring system is urgently needed in the field of large facility engineering structure detection or monitoring.
Disclosure of Invention
The invention aims to solve the problems in the prior art, and provides a deflection measuring system and method based on stereoscopic vision, which adopt a double-measuring-station mode, utilize a double-camera combined remote distance and angle measuring module to realize non-contact measurement of deflection of large facilities, overcome the requirement limitation on a reference object in monocular vision image measurement, have the advantages of simple and convenient installation, large measuring range, high measuring precision, multipoint simultaneous measurement, high detection efficiency and the like, simultaneously consider field measurement environmental factors, provide an image enhancement method for eliminating uneven illumination and haze, better meet the actual requirements of engineering detection and have wide application range.
In order to achieve the purpose, the invention adopts the technical scheme that:
a deflection measuring system based on stereoscopic vision comprises an image acquisition module, a distance and angle measuring module, a control module and a data processing module; the image acquisition module, the distance and angle measurement module and the control module are all connected with the data processing module; the control module controls the image acquisition module and the distance and angle measurement module to acquire data respectively, the image acquisition module and the distance and angle measurement module transmit the acquired data to the data processing module respectively in real time, and the data processing module is combined with the acquired data to perform real-time dynamic analysis and display the deflection value of a target point to be measured.
Preferably, the image acquisition module comprises a camera, a lens and an image acquisition card.
Furthermore, the camera adopts an industrial camera with more than 2500 ten thousand pixels and the frame rate of 200fps, and adopts a CXP interface; the lens adopts low-distortion lenses with different focal lengths, so that the measurement requirements of different working distances and different view field sizes are met; the image acquisition card adopts a CXP interface, and the data transmission rate is matched with the camera; the camera is connected with the image acquisition card and the computer in sequence.
Preferably, the distance and angle measuring module comprises a laser distance meter, an azimuth angle module, a pitch angle module and an industrial tripod; the laser range finder is arranged above the pitch angle module, the azimuth angle module is arranged on the industrial tripod, the pitch angle module is connected to the azimuth angle module, and the camera is arranged on the pitch angle module; the laser range finder is used for measuring the baseline distance of the two cameras and the distance between each measured target point and the target surface of the camera; the azimuth module comprises an azimuth motor, an azimuth shaft and a circular grating, the azimuth motor drives the azimuth module to rotate to adjust the azimuth of the camera, and the circular grating on the azimuth shaft is used for measuring the azimuth of the camera in real time; the pitch angle module comprises a pitch motor, a pitch shaft, a circular grating and an electronic tilt angle sensor, the pitch motor drives the pitch angle module to rotate to adjust the pitch angle of the camera, the circular grating on the pitch shaft is used for measuring the pitch angle of the camera in real time, and the electronic tilt angle sensor is rigidly connected with the pitch angle module and acquires the roll angle of the camera in real time.
Preferably, the image acquisition module and the distance and angle measurement module form double measuring stations, and each measuring station adopts the same design and configuration; the double measuring stations are installed on the stable ground and at the positions where the vision range is not blocked, and the distance between the double measuring stations and the measured structure is 1-500 m.
Preferably, the control module comprises a synchronous controller, an azimuth angle driver, a pitch angle driver and a data acquisition system.
Furthermore, the synchronous controller sends trigger signals to the two cameras simultaneously to synchronize image acquisition of the cameras, the azimuth angle driver controls rotation of the azimuth angle module, the pitch angle driver controls rotation of the pitch angle module, and the data acquisition system is responsible for data acquisition of the laser range finder, the circular grating and the electronic tilt sensor.
Preferably, the data processing module has functions of data real-time analysis, result display and data storage, and can start the early warning function when the deflection value of the measured structure exceeds a safety threshold value.
A deflection measurement method based on stereoscopic vision is realized by adopting the system, and comprises the following steps:
1) arranging two measuring stations;
2) calibrating a camera;
3) synchronously acquiring images;
simultaneously sending a trigger signal to the two-phase machine, and synchronously acquiring images in real time by the two-phase machine according to the set sampling frequency;
4) image enhancement processing;
respectively enhancing the acquired images by adopting an algorithm based on continuous mean value quantization transformation and a multi-scale Retinex algorithm;
5) spatial coordinate calculation
After two images acquired by two cameras at the same time are subjected to enhancement processing, pixel coordinates of a measured point in the two images are extracted, and three-dimensional space coordinates (X, Y and Z) of the measured point are solved according to a corresponding relation between the pixel coordinates and the three-dimensional space coordinates established by camera calibration;
6) calculating a deflection value;
if the space coordinate of the measured point at the moment t is (X)t,Yt,Zt) The spatial coordinate of the measured point at the time t +1 is (X)t+1,Yt+1,Zt+1) And the deflection value of the measured point at the time interval from t to t +1 is:
d＝Zt+1-Zt。
specifically, the deflection measuring method is used for measuring the deflection of large facility engineering structures such as bridges, deflection curves of the measured points can be obtained by calculating deflection values at different moments, and the purpose of real-time safety monitoring is achieved according to a deflection threshold value set in a system.
Specifically, an algorithm based on continuous mean value quantization transformation is adopted to perform enhancement processing on images acquired by two cameras, so as to eliminate the influence of serious dark or bright images caused by the change of field sunlight; the method is characterized in that images acquired by two cameras are subjected to enhancement processing based on a multi-scale Retinex algorithm, and the purpose is to remove the influence of unclear images caused by haze.
Preferably, arranging the dual measuring station further comprises:
selecting corresponding lenses according to the measurement conditions of the target points to be measured, placing the two measurement stations in a crossed manner from different angles, and enabling all the target points to be measured to be displayed in the image acquired by the two cameras by adjusting the distance and the angle between the two measurement stations; adjusting an azimuth angle module and a pitch angle module to enable the initial azimuth angle and the initial pitch angle of the two cameras to be zero, controlling the azimuth angle module to rotate to enable the two cameras to be in strict sight to obtain a baseline distance L of the two cameras, and controlling the azimuth angle module to rotate reversely to enable the two cameras to return to the initial positions; finally, the azimuth angle module is controlled to rotate to enable the two cameras to face the direction of a target to be measured, azimuth angles of the two cameras are obtained through the circular gratings on the azimuth axis respectively, then the pitch angle module is controlled to rotate to enable the two cameras to be accurately aligned to the target to be measured, the pitch angles of the two cameras are obtained through the circular gratings on the pitch axis respectively, and roll angles of the two cameras are obtained through the electronic tilt angle sensors respectively;
preferably, the camera calibration further comprises:
determining internal parameters K of two cameras by adopting Zhangyingyou calibration methodl、KrThe internal parameters include principal point coordinates (u)0,v0)TEquivalent focal length fx、fy(ii) a Determining the basis matrix F of stereoscopic vision according to the epipolar geometry principlelr(ii) a Constraint relation according to basis matrix
Solving the intrinsic matrix E of stereo visionlr(ii) a Obtaining a rotation matrix R between the two cameras through the calculation of azimuth angles, pitch angles and roll angles respectively provided by the circular grating and the electronic tilt angle sensor, and obtaining an essential matrix Elr＝[t]×R and the rotation matrix R obtain a translation vector t with a proportionality coefficient, and the translation vector between the two cameras is
Finally, optimizing internal parameters K of the two cameras by using a light beam adjustment methodl、KrAnd extrinsic parameters R, T.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention adopts a non-contact measurement mode, and solves the problems of complex installation, low measurement efficiency and the like of the traditional methods such as a contact displacement sensor and the like;
(2) the invention adopts double cameras to collect target images on a measured structure in real time, and realizes the real-time measurement of three-dimensional deformation displacement of a plurality of measured target points by tracking specific mark points or specific textures on a large structure and an image correlation calculation method;
(3) the two measuring stations are independent and have the same structural configuration, the placing position can be flexibly adjusted according to the measuring environment, the corresponding lens is selected by combining different distances and different view field conditions, the common view field of the two cameras is ensured to be large enough, the shooting distance range is 1-500 m, the two measuring stations can be used for both close-range measurement and long-distance and large-view-field measurement, and the applicability is improved;
(4) the invention adopts the parameters such as the baseline distance, the Euler angle and the like provided by the distance measuring and angle measuring module, is beneficial to the calibration of the camera and reduces the error;
(5) according to the invention, the influence of uneven illumination and haze is removed by adopting an image enhancement algorithm, the image quality is improved, the deflection measurement precision is further improved, and the actual requirement of field detection is better met.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic diagram of the system of the present invention according to an embodiment;
FIG. 2 is a schematic diagram of a dual measurement station of the present invention according to an embodiment;
FIG. 3 is a schematic flow chart of the method of the invention for measuring deflection according to an embodiment.
In the figure: the system comprises an image acquisition module, a camera 11, a camera 12, a lens 13, an image acquisition card 2, a distance and angle measurement module 21, a laser range finder 22, an azimuth angle module 23, a pitch angle module 24, an industrial tripod, a control module 3 and a data processing module 4.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, the invention provides a deflection measuring system based on stereoscopic vision, which comprises an image acquisition module 1, a distance and angle measuring module 2, a control module 3 and a data processing module 4; the image acquisition module 1 and the distance and angle measurement module 2 are connected with the control module 3, and the image acquisition module 1, the distance and angle measurement module 2 and the control module 3 are connected with the data processing module 4; the control module 3 controls the image acquisition module 1 and the distance and angle measurement module 2 to respectively acquire data (acquired data comprise target images, pose parameters and the like), the image acquisition module 1 and the distance and angle measurement module 2 respectively transmit the detected data to the data processing module 4 in real time, and the data processing module 4 dynamically analyzes and displays the deflection value of a target point to be measured in real time by combining the data.
As shown in fig. 2, a deflection measuring system based on stereoscopic vision adopts a dual-measuring-station mode, the two measuring stations are independent and have the same structural configuration, and the dual-measuring-station mode comprises an image acquisition module 1 and a distance and angle measuring module 2; the image acquisition module 1 comprises a camera 11, a lens 12 and an image acquisition card 13; the camera 11 adopts an industrial camera with more than 2500 ten thousand pixels and a frame rate of 200fps, and the camera 11 adopts a CXP interface; the lens 12 adopts low-distortion lenses with different focal lengths, so that the measurement requirements of different working distances and different view field sizes are met; the image acquisition card 13 adopts a CXP interface, and the data transmission rate is matched with the camera; the camera 11 is sequentially connected with the image acquisition card 13 and the computer, and the high-frame-rate camera and CXP image acquisition card combined mode can realize high-speed image acquisition so as to meet the requirement of acquiring clear images of a detected target under a high-frequency vibration working condition and is more beneficial to subsequent analysis and processing of the images.
The distance and angle measurement module 2 comprises a laser distance meter 21, an azimuth angle module 22, a pitch angle module 23 and an industrial tripod 24; the laser range finder 21 is arranged above the pitch angle module 23, the azimuth angle module 22 is arranged on the industrial tripod 24, the pitch angle module 23 is connected to the azimuth angle module 22, and the camera 11 is arranged on the pitch angle module 23; the laser range finder 21 is used for measuring the baseline distance between the two cameras 11 and the distance between each measured target point and the target surface of the cameras; the azimuth module 22 comprises an azimuth motor, an azimuth shaft and a circular grating, the azimuth motor drives the azimuth module 22 to rotate and adjust the azimuth of the camera 11, and the circular grating on the azimuth shaft is used for measuring the azimuth of the camera 11 in real time; the pitch angle module 23 comprises a pitch motor, a pitch shaft, a circular grating and an electronic tilt angle sensor, the pitch motor drives the pitch angle module 23 to rotate to adjust the pitch angle of the camera 11, the circular grating on the pitch shaft is used for measuring the pitch angle of the camera 11 in real time, and the electronic tilt angle sensor is rigidly connected with the pitch angle module 23 and acquires the roll angle of the camera 11 in real time.
The control module 3 comprises a synchronous controller, an azimuth angle driver, a pitch angle driver, a data acquisition system and the like; the synchronous controller sends trigger signals to the two cameras 11 simultaneously to synchronize image acquisition of the cameras, the azimuth angle driver controls rotation of the azimuth angle module 22, the pitch angle driver controls rotation of the pitch angle module 23, and the data acquisition system is responsible for data acquisition of the laser range finder 21, the circular grating and the electronic tilt angle sensor.
The data processing module 4 has functions of data real-time analysis, result display and data storage, and can start an early warning function when the flexibility value of the tested structure exceeds a safety threshold, and the setting of the safety threshold can be determined by combining the corresponding standard allowable value, the engineering experience value or the long-term monitoring data statistical analysis value and the like.
A method for measuring the deflection of large facility engineering structures such as bridges by adopting a deflection measuring system based on stereoscopic vision comprises the following steps:
1) arranging two measuring stations;
selecting corresponding lenses according to the measurement conditions of the target points to be measured, placing the two measurement stations in a crossed manner from different angles, and enabling all the target points to be measured to be displayed in the image acquired by the two cameras by adjusting the distance and the angle between the two measurement stations; adjusting an azimuth angle module and a pitch angle module to enable the initial azimuth angle and the initial pitch angle of the two cameras to be zero, controlling the azimuth angle module to rotate to enable the two cameras to be in strict sight to obtain a baseline distance L of the two cameras, and controlling the azimuth angle module to rotate reversely to enable the two cameras to return to the initial positions; finally, the azimuth angle module is controlled to rotate to enable the two cameras to face the direction of a target to be measured, azimuth angles of the two cameras are obtained through the circular gratings on the azimuth axis respectively, then the pitch angle module is controlled to rotate to enable the two cameras to be accurately aligned to the target to be measured, the pitch angles of the two cameras are obtained through the circular gratings on the pitch axis respectively, and roll angles of the two cameras are obtained through the electronic tilt angle sensors respectively;
2) calibrating a camera;
firstly, determining internal parameters K of two cameras by adopting Zhangyingyou calibration methodl、KrThe internal parameters include principal point coordinates (u)0,v0)TEquivalent focal length fx、fy(ii) a Determining the basis matrix F of stereoscopic vision according to the epipolar geometry principlelr(ii) a Constraint relation according to basis matrix
Solving the intrinsic matrix E of stereo visionlr(ii) a Obtaining a rotation matrix R between the two cameras through the calculation of azimuth angles, pitch angles and roll angles respectively provided by the circular grating and the electronic tilt angle sensor, and obtaining an essential matrix Elr＝[t]×R and the rotation matrix R obtain a translation vector t with a proportionality coefficient, and the translation vector between the two cameras is
Finally, optimizing internal parameters K of the two cameras by using a light beam adjustment methodl、KrAnd extrinsic parameters R, T;
3) synchronously acquiring images;
the control module simultaneously sends a trigger signal to the two-phase machine, and the two-phase machine synchronously collects images in real time according to the set sampling frequency; the system provides two synchronous forms of cable and wireless;
4) image enhancement processing;
in order to eliminate the influence of serious dark or bright images caused by the change of field sunlight, an algorithm based on continuous mean value quantization transformation is adopted to perform enhancement processing on the images acquired by the two cameras; in order to remove the influence of unclear images caused by haze, images acquired by two cameras are enhanced by adopting a multi-scale Retinex algorithm;
5) spatial coordinate calculation
After two images collected by two cameras at the same time are subjected to enhancement processing, pixel coordinates (u) of a measured point in the two images are extractedl,vl)、(ur,vr) And according to the corresponding relation between the pixel coordinate and the three-dimensional space coordinate established by the calibration of the image camera:
solving the three-dimensional space coordinates (X, Y, Z) of the measured point by using a least square method;
6) calculating a deflection value;
if the space coordinate of the measured point at the moment t is (X)t,Yt,Zt) The spatial coordinate of the measured point at the time t +1 is (X)t+1,Yt+1,Zt+1) Then the deflection value of the measured point at the time interval is:
d＝Zt+1-Zt
the deflection curve of each measured point can be obtained by calculating the deflection value at different moments, and the purpose of real-time safety monitoring is achieved according to the deflection threshold value set in the system. Meanwhile, according to the requirement of the measured structure, the system can also be used for calculating the transverse and longitudinal displacement of the measured point on the structure.
The invention provides a deflection measuring system and method based on stereoscopic vision, which comprises an image acquisition module, a distance and angle measuring module, a control module and a data processing module, wherein the control module controls the image acquisition module and the distance and angle measuring module to respectively acquire data such as target images, pose parameters and the like, the image acquisition module and the distance and angle measuring module respectively transmit the detected data to the data processing module in real time, the data processing module reconstructs three-dimensional geometric information of a detected target by using a parallax principle, and the deflection value of each detected point is obtained by calculating the space coordinate change of each detected target point on adjacent interval image frames. The system adopts a double-measuring-station mode, the two measuring stations are independent and have the same structural configuration, the placing positions are flexible, the common visual field is ensured to be large enough, the system can be used for close-range measurement and long-distance large-visual-field measurement, the influence of uneven illumination and haze is removed by adopting an image enhancement algorithm, the deflection measurement precision is improved, and the actual requirement of engineering detection is better met.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (3)
1. The deflection measuring system based on the stereoscopic vision is characterized by comprising an image acquisition module (1), a distance and angle measuring module (2), a control module (3) and a data processing module (4); the image acquisition module (1) and the distance and angle measurement module (2) are connected with the control module (3), and the image acquisition module (1), the distance and angle measurement module (2) and the control module (3) are connected with the data processing module (4); the control module (3) controls the image acquisition module (1) and the distance and angle measurement module (2) to respectively acquire data, the image acquisition module (1) and the distance and angle measurement module (2) respectively transmit the acquired data to the data processing module (4) in real time, and the data processing module (4) is combined with the acquired data to perform real-time dynamic analysis and display the deflection value of a target point to be measured;
the image acquisition module (1) comprises a camera (11), a lens (12) and an image acquisition card (13);
the distance and angle measuring module (2) comprises a laser distance meter (21), an azimuth angle module (22), a pitch angle module (23) and an industrial tripod (24); the laser range finder (21) is arranged above the pitch angle module (23), the azimuth angle module (22) is arranged on the industrial tripod (24), the pitch angle module (23) is connected to the azimuth angle module (22), and the camera (11) is arranged on the pitch angle module (23); the laser range finder (21) is used for measuring the baseline distance of the two cameras (11) and the distance between each target point to be measured and the target surface of the camera; the azimuth module (22) comprises an azimuth motor, an azimuth shaft and a circular grating, the azimuth motor drives the azimuth module (22) to rotate to adjust the azimuth of the camera (11), and the circular grating on the azimuth shaft is used for measuring the azimuth of the camera (11) in real time; the pitching angle module (23) comprises a pitching motor, a pitching shaft, a circular grating and an electronic inclination angle sensor, the pitching motor drives the pitching angle module (23) to rotate to adjust the pitching angle of the camera (11), the circular grating on the pitching shaft is used for measuring the pitching angle of the camera (11) in real time, and the electronic inclination angle sensor is rigidly connected with the pitching angle module (23) and acquires the rolling angle of the camera (11) in real time;
the image acquisition module (1) and the distance and angle measurement module (2) form double measuring stations, and each measuring station adopts the same design and configuration; the double measuring stations are arranged on the stable ground and are not shielded in the visual field range, and the distance between the double measuring stations and the measured structure is 1-500 m;
the measuring method of the deflection measuring system based on the stereoscopic vision comprises the following steps:
1) arranging two measuring stations;
selecting corresponding lenses according to the measurement conditions of the target points to be measured, placing the two measurement stations in a crossed manner from different angles, and enabling all the target points to be measured to be displayed in the image acquired by the two cameras by adjusting the distance and the angle between the two measurement stations; adjusting an azimuth angle module and a pitch angle module to enable the initial azimuth angle and the initial pitch angle of the two cameras to be zero, controlling the azimuth angle module to rotate to enable the two cameras to be in strict sight to obtain a baseline distance L of the two cameras, and controlling the azimuth angle module to rotate reversely to enable the two cameras to return to the initial positions; finally, the azimuth angle module is controlled to rotate to enable the two cameras to face the direction of a target to be measured, azimuth angles of the two cameras are obtained through the circular gratings on the azimuth axis respectively, then the pitch angle module is controlled to rotate to enable the two cameras to be accurately aligned to the target to be measured, the pitch angles of the two cameras are obtained through the circular gratings on the pitch axis respectively, and roll angles of the two cameras are obtained through the electronic tilt angle sensors respectively;
2) calibrating a camera;
firstly, determining internal parameters K of two cameras by adopting Zhangyingyou calibration methodl、KrThe internal parameters include principal point coordinates (u)0,v0)TEquivalent focal length fx、fy(ii) a Determining the basis matrix F of stereoscopic vision according to the epipolar geometry principlelr(ii) a Constraint relation according to basis matrix
Solving the intrinsic matrix E of stereo visionlr(ii) a Obtaining a rotation matrix R between the two cameras through the calculation of azimuth angles, pitch angles and roll angles respectively provided by the circular grating and the electronic tilt angle sensor, and obtaining an essential matrix Elr＝[t]×R and the rotation matrix R obtain a translation vector t with a proportionality coefficient, and the translation vector between the two cameras is
Finally, optimizing internal parameters K of the two cameras by using a light beam adjustment methodl、KrAnd extrinsic parameters R, T;
3) synchronously acquiring images;
the control module simultaneously sends a trigger signal to the two-phase machine, and the two-phase machine synchronously collects images in real time according to the set sampling frequency; the system provides two synchronous forms of cable and wireless;
4) image enhancement processing;
in order to eliminate the influence of serious dark or bright images caused by the change of field sunlight, an algorithm based on continuous mean value quantization transformation is adopted to perform enhancement processing on the images acquired by the two cameras; in order to remove the influence of unclear images caused by haze, images acquired by two cameras are enhanced by adopting a multi-scale Retinex algorithm;
5) spatial coordinate calculation
After two images collected by two cameras at the same time are subjected to enhancement processing, pixel coordinates (u) of a measured point in the two images are extractedl,vl)、(ur,vr) And according to the corresponding relation between the pixel coordinate and the three-dimensional space coordinate established by the calibration of the image camera:
solving the three-dimensional space coordinates (X, Y, Z) of the measured point by using a least square method;
6) calculating a deflection value;
if the space coordinate of the measured point at the moment t is (X)t,Yt,Zt) The spatial coordinate of the measured point at the time t +1 is (X)t+1,Yt+1,Zt+1) Then the deflection value of the measured point at the time interval is:
d＝Zt+1-Zt
and (4) calculating the deflection values at different moments to obtain the deflection curve of each measured point.
2. The deflection measuring system based on stereoscopic vision according to claim 1, characterized in that the control module (3) comprises a synchronization controller, an azimuth angle driver, a pitch angle driver, a data acquisition system.
3. The deflection measuring system based on stereoscopic vision according to claim 1, wherein the data processing module (4) has functions of data real-time analysis, result display and data storage, and when the deflection value of the measured structure exceeds a safety threshold, an early warning function is started.
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