基于相位移编码圆的相机离焦快速标定方法

Fast calibration method of camera defocus based on phase shift coding circle

针对大范围视觉系统相机标定难度大、效率低的问题,提出了一种基于相位移编码圆的相机离焦快速标定方法。该方法首先通过相位移编码圆实现离焦状态下的特征点提取;利用标靶空间位置信息构建出单目相机的目标函数,并采用非线性最小二乘法求解相机的内部参数;通过建立双目系统的目标优化函数解析出相机系统的外部参数。该方法无需移动相机或标靶,通过拍摄3幅相位移圆图像,即可完成大范围视觉系统相机离焦状态下的快速标定。经实验验证:标定焦距偏差在0.5%以内,逆向投影误差最大为0.33pixel,解决了大范围视觉系统相机标定难度大、效率低的难题。

To resolve the difficulty and low efficiency problem of camera calibration for large-scale vision system, a fast calibration method for camera defocus based on phase shift coding circle is proposed. Firstly, the feature points are extracted in the defocused state by using the phase shift coding circle. Secondly, the target function of monocular camera is constructed through utilizing spatial location information given by the calibration target, and then make use of the nonlinear least square method to solve the internal parameters of the camera. Finally, by establishing the optimization function of the binocular system, the external parameters of the camera system are solved. This method does not need to move the camera or target, and can complete the rapid calibration of the large-scale vision system camera in the defocused state by shooting 3 phase-shift circle images. The experiment results shows that the deviation of the calibrated focal length is less than 0.5%, and the maximum inverse projection error is 0.33 pixel, which solves the difficult and low efficiency problems of large-scale vision system camera calibration.