Improvement in camera calibration based on RAC

The two-stage technique proposed by Tsai has advantage in terms of accuracy, speed, and versatility over existing state of the art. But it does not calibrate the image center so that the errors in the translation and rotation are induces by choosing a wrong image center. The proposed technique only requires the camera to observe a planar pattern shown at a few (at least two) different orientations and computes the image center using Z.Zhang method. The remaining parameters are calibrated with the accurate center estimate. Finally, we can refine the above solution through maximum likelihood criterion. Real data has been used to test the proposed technique and very good results have been obtained. Compared with Tsai's method, the proposed method is more accurate and simple.