Study Of Camera Calibration Method Based On Cooperation Calibration Objects

Camera calibration is an important work in the field of computer vision. In particular, it is an important technique in vision measurement system. Camera calibration accuracy has a great influence on the measurement accuracy of the entire visual measurement system. Camera calibration methods are generally divided into three categories: traditional method, active vision camera calibration method, self-calibration method. According to the actual project needs, the requirement for camera calibration method is simple operation and high accuracy. Based on these requirements, this article focuses on research cooperation objects calibration method, which is the traditional method.This paper introduces the basic theory of calibration, focusing on the conversion relationship between the three-dimensional space points and the computer frame buffer image points. It provides a reliable theoretical support for the proposed camera calibration methods.Zhang’s calibration method is widely used on the actual visual measurement system because of its relatively simple calibration process, accurate calibration results. The method solves only two-stage radial distortion coefficients, In order to fully study the performance of the method by simulation experiments, the effects of higher-order radial distortion of the method has been explored.At the same time, this paper proposed a camera calibration method based on division model, on the basis of Zhang’s calibration method. The method skillfully solves distortion coefficients and homographic matrix simultaneously, and obtains equivalent accuracy calibration results with Zhang’s method in the case of not using nonlinear optimization. Meanwhile, when the distortion center and the main point don’t overlap, the distortion center parameter is added. The simulation and the experiment show the accuracy of calibration results.There are three classical methods of camera calibration based on cooperation objects, wherein the linear method is the simplest and most efficient calibration method. Because the camera distortion has not been considered, it is inadequate in the calibration accuracy. According to the actual needs of the project, a camera calibration method based on the marker is proposed in this paper, on the basis of classical linear calibration method. We continue estimate radial distortion, and, all parameters are optimized by nonlinear optimization. Actual experiment proves the correctness of the method.Camera calibration system is built, and 10 complete camera calibration experiments are carried out, 10 calibration results are obtained. By analyzing of the calibration results, the calibration system is simple, practical and correct.