Research On Calibrtion Method In Monocular Structure Light System

With the development of measurement technology and computer,threedimensional measurement is becoming an important area of research in computer vision.Using the three-dimensional measurement technology can achieve cultural relic protection,face detection,industrial detection and intelligent manufacturing.Monocular structured light measurement system has become a common threedimensional measurement method because it has no contact with the object,as well as high precision,fast speed and other advantages.In this paper,aiming at the problem that the calibration accuracy of the existing structured light system is not high,the method of extracting corner points,and the calibration of camera and system for checkerboard which affect the measurement accuracy have been discussed based on the simple and compact three-dimensional measurement system of monocular structured light.Firstly,based on the in-depth research on camera calibration and system calibration method in structured light system,the digital imaging model and distortion model of the camera are established.Considering the projector imaging model as the reverse camera imaging model,the system measurement model combining camera and projector is readily constructed.Secondly,linking the two-dimensional between checkerboard calibration board image coordinates of the corner and the three-dimensional coordinates in the world coordinate system.The principle and process of Bouguet sub-pixel corner extraction algorithm are studied in detail.In order to solve the problem in poor illumination condition and the large lens distortion of Bouguet algorithm,a checkerboard corner extraction algorithm based on the feature of corner distribution is proposed.The advantages of the proposed algorithm in robustness and accuracy are analyzed by comparing the images of the checkerboard calibration board.Finally,the calibration algorithm of monocular structured light system is studied and analyzed.The camera calibration,projector calibration and system calibration are separately studied.In the camera calibration,a linear calibration method based on distortion center is presented the deficiency of zhang zhengyou calibration method;In the projector calibration,binary quadratic polynomials are used to decrease the errors in the mapping between camera pixel coordinates and projector pixel coordinates through a homography matrix.Finally,a measurement system experiment platform composed of camera and projector was built.The calibration experiment of camera,projector and system was conducted in which the data is collected by camera image acquisition software.The effectiveness of the calibration method is verified by using the reprojection error as the accuracy evaluation criterion.Above all,the effective calibration of monocular structured light system is realized,and the calibration accuracy of camera and projector is improved which is beneficial to improve the precision of measurement of structured light.