基于同心圆光栅和契形光栅的摄像机自标定方法

提出一种利用同心圆光栅和契形光栅作为标定模板,基于正交方向消失点摄像机自标定的新方法。新方法利用相移条纹相位提取精度高的特性来求零相位特征点,避免了传统标记点提取误差给标定结果带来的影响。要求摄像机至少从6个方位拍摄标靶,采用四步相移得到光栅的截断相位并求解零相位交点,计算消失点从而解算出摄像机的内参数。根据模拟实验得到影响消失点标定精度因素的分析结果,制作了含有7个周期的同心圆光栅和4个周期的契形光栅。实际测量实验中分别用光栅靶标和灰度同心圆靶标进行相机标定,对比重投影误差,结果证明新方法提高了基于消失点标定算法的精度和稳健性。

An Concentric Circles and Wedge Grating-Based Camera Self-Calibration Method

A new method for camera calibration by using concentric circles and wedge grating based on the orthogonal vanishing point calibration is proposed. This method uses the characteristics of the high-precision of the phase extraction to obtain the feature points, thus avoiding the calibration errors caused by the traditional marker extraction errors. The camera should capture the pattern images at least six positions. The wrapped phase of the grating can be gained by four-step phase shifting and the zero phase intersection points coordinate of the wrapped phase are calculated from images. The vanishing points and all the intrinsic parameters of the camera can be calculated. According to the simulation experiment analysis results which include factors influencing the vanishing point calibration accuracy, the concentric circles grating with seven periods and the wedge grating with four periods are designed. In the real measuring experiment, the grating target and gray concentric circles target are used to calibrate the camera respectively. Through comparing the reprojective errors of the two methods, it can be proved that the method proposed improves the calibration accuracy and robustness for the vanishing point calibration algorithm.