Iterative projector calibration using multi-frequency phase-shifting method

In this paper, an iterative projector calibration method is proposed using multi-frequency phase-shifting methods. With the help of the multi-frequency phase shifting, the projector can `see´ the 3D control point from the correspondence between the camera image and the projector image. The 3D control point information is directly adopted instead of computing them from the calibrated camera. Thus, the error propagation from the camera calibration is avoided. To diminish the influence of the lens distortion and the projective transformation, an iterative refining method is adopted to approach the real canonical fronto-parallel image from the camera image instead of the projector image. Because the canonical fronto-parallel image is determined by the virtual camera and the pose of calibration board, they are same from the camera image and the projector image to generate the canonical fronto-parallel image. However, it is complicated and time-consuming to obtain it from the projector image, because the projector image has to be created from the correspondence at first. The proposed method is conducted in our portable structured light system. It is compared with the non-iterative method. The results confirm that the proposed method has higher accuracy.