Demonstration of a simple and flexible calibration method for structured light system

The calibration of the system’s geometric parameters is always an important step in 3D topography measurement based on fringe projection profilometry. However, the traditional calibration method needs to be realized by the implementation of an electric guide rail, which exhibits certain problems, such as complicated operation and inconvenient carrying. Along these lines, in this work, a new simple and flexible calibration method is introduced. For the proposed method, a round calibration board only needs to be moved arbitrarily many times within the depth of field of the camera and projector. By using the existing camera calibration method, each calibration plate position and pose can be derived, while the phase of every pixel and the height data, as well as the phase of every pixel-height mapping relationship, were established. In addition, the rational function fitting method was used to accurately estimate the phase distribution of the black area of the calibration plate, avoiding thus the influence of the phase artifacts caused by high-contrast calibration targets. The minimum root mean square error (RMSE) of the experimental results was 0.074 mm. Compared with the traditional method, our approach is more flexible and convenient, and has no loss of reliability.