基于交比不变性的投影仪标定

提出了一种新的投影仪标定方法以提高数字光栅投影三维测量中投影仪标定的准确性。该方法结合二次投影技术和交比不变性进行投影仪标定。采用二次投影技术解决投射图案与标定板图案互相干扰的问题;采用交比不变性以避免引入相机的标定误差。接着进行了对比实验,以验证所提方法的有效性。选取需要相机参数的传统投影仪标定方法以及根据全局单应性的投影仪标定方法作为对比方法。结果显示,本方法的反投影误差标准差分别从(0.2275,0.2264)像素和(0.1397,0.0997)像素降低到(0.0645,0.0601)像素,反投影误差的最大值分别从1.222像素和0.5617像素降低到0.2421像素。另外,该方法还可同时标定相机,从而获得整个三维测量系统的参数。本文提出的方法可以避免相机标定参数的误差传递,提高投影仪的标定精度。

Projector calibration based on cross ratio invariance

In order to improve the accuracy of the projector calibration in 3D shape measurement using digital fringe projection,a new projector calibration method that combines secondary projection technology and cross-ratio invariance is proposed.The secondary projection technology is used to solve the mutual interference between the projection pattern and the calibration pattern,and the cross-ratio invariance method is used to avoid introducing camera calibration error.A comparative experiment is carried out to verify the effectiveness of the proposed method.Compared with the traditional method of projector calibration that requires camera parameters and that using global homography,the RMS values of reprojection error of this method is reduced from(0.2275,0.2264)and(0.1397,0.0997)pixels to(0.0645,0.0601)pixels,and the maximum value of the reprojection error is reduced from 1.222 pixels and 0.5617 pixels to 0.2421 pixels.In addition,this method allows the camera to be simultaneously calibrated during operation,and therefore the parameters of the entire 3D measurement system can be acquired.The above results show that the method proposed in this paper can prevent error propagation of camera calibration parameters and improve the calibration accuracy of a projector.