Research On Camera Calibration Method Based On The Properties Of Orthogonal Vanishing Point

With the improvement of camera in image resolution, image sampling rate and computer image processing speed, in addition to the general monitoring, computer vision field camera was more and more widely used in the field of 3D scanning, visual detection, 3D measurement, and measurement accuracy and is getting higher and higher, and camera calibration is playing an increasingly important role.This dissertation focuses on the two important aspects of the camera calibration process,the corner detection and camera calibration parameters, complete the following research work:Firstly, this dissertation studies the detection problem of image feature points. In view of the shortcomings of Harris corner detection algorithm in accuracy, real-time and so on, an improved sub-pixel corner detection algorithm is chose. And in real-time aspect, it is also a significant optimization.Secondly, this dissertation introduces the relationship between the four coordinate systems and the linear and nonlinear models of camera calibration. Based on simplified four internal parameters, by using the 3D world coordinates of the corner point of the board and the projection to the image coordinates of the 2D camera, an improved camera calibration method based on coplanar points is proposed, using Levenberg-Marquardt algorithm for nonlinear least squares to optimize the calibration parameters. Simulation results show that the improved algorithm has good performance in accuracy and stability, and it has certain advantages in comparison with the results of the Zhang`s calibration algorithm.Lastly, according to the need of camera calibration, a camera self calibration method based on the orthogonal vanishing point is proposed. It not only does not require accurate chessboard template, but also do not need to use accurate and controllable high-precision camera mobile platform. According to the geometric characteristics of image linear features calculated linear vanishing point location, and based on the vanishing point geometry and camera calibration model theory, shooting four images obtained 4 groups of vanishing points to achieve the camera calibration of camera intrinsic parameters and the distortion coefficient,If you know the coordinates of the corresponding feature points in the world coordinate system, the calibration of the camera parameters can be also achieved. Simulation results show that the algorithm is effective and feasible, and it can be applied to the occasion. It has more practical significance.