A Flexible Calibration Method for Fringe Projection Profilometry

The fringe projection profilometry (FPP) is an optical method which reconstruction 3D object by using structured light. The Calibration is inevitable in FPP. The calibration procedure is to establish a connection between height and light field information. The existing calibration methods usually need precise z stages and/or interpolation on markers and are complex and time-cost. We present a flexible calibration algorithm for fringe projection profilometry. It avoids these by using ray-phase model and designing a two-step calibration procedure. The ray-phase equations formulate the relation of 3D coordinates and phase. During the calibration procedure, an auxiliary camera is introduced to construct a stereo vision system with measurement system. Firstly, the stereo vision system is calibrated by using traditional method. Then the coordinates and absolute phases, which are both obtained by measuring the calibration object with the stereo vision system, are applied to fit ray-phase equations. Both theoretical analysis and experimental results are provided. In the experiment, standard deviation of the plane is 0.0422 mm. They show that our calibration algorithm is flexible, feasible and accurate.