Projector calibration method using orthogonal gray code combined with trapezoid phase shift code

Abstract

In coded-structured light three dimensional measurement system, system calibration plays an important role for the measurement accuracy. Projector calibration is an important part of the system calibration. Therefore, this paper proposes a projector calibration method with simple calibration process and high accuracy. This method combines Zhang’s plane model calibration method with orthogonal Gray code + trapezoid phase shift code. During the calibration process, this paper uses Gray code pattern and trapezoid phase shift code pattern to establish the relation of projector image and camera point coordinates, the corner extraction accuracy of this paper’s method is higher than the traditional orthogonal Gray code. According to the image coordinates in the projector’s perspective, we program and calculate the projector’s internal and external parameters matrix based on the Zhang’s plane model calibration toolbox. The results show that this paper’s method is simple and flexible, the maximum relative error of the calibration parameters is 0.027%, and it meets the requirements of system calibration in engineering or industrial fields.