High-precision calibration for wholly parametric plane linear estimation algorithm of projector

To solve the problem that the complex optical path of projector and the large deflection of main point are difficult to meet the requirement of high-precision calibration, a wholly parametric plane linear estimation algorithm of the projector was put forward to determine the initial deviation value of main point. Thus, the wholly parametric high precision calibration of the projector can be fulfilled. Firstly, the projector is treated as a virtual camera to obtain the coordinates of the projector and the calibration board through multiple frequency phase shift principle. Secondly, a two-step method is utilized to solve the nonlinear equations. To obtain the stable direct parameter estimation, a vector parameter is introduced to solve the linearization of the nonlinear equation and an optimal point set is selected by affine transformation relationship. Finally, a global bundle adjustment algorithm is developed to implement high precision calibration of the projector. After the calibration of single camera system, the standard balls are measured to verify its accuracy. The experimental results showed that the average value of the projector-camera system's re-projection error is 0.04 pixel, and the average deviation is less than 0.1 mm in diameter and 0.05 mm in distance acquired by the standard balls. The results further indicate that the algorithm model is simple, stable and accurate. Above all, the projector calibration algorithm can be applied to the situation that the displacement of main point has a large deviation and focal length is unknown.