A novel calibration method for arbitrary fringe projection profilometry system

Abstract

A novel calibration method for phase-to-height (PTH) relationship in fringe projection profilometry (FPP) was proposed in this work. This proposed method can be applied to an FPP system of which the camera, projector and reference plane are positioned arbitrarily. First, a black-white pattern and four phase-shifted sinusoidal patterns are generated using a computer and projected onto the reference plane (ow-xw-yw coordinate plane) while being moved along its normal direction to several known positions. The camera records the projected fringe patterns on the reference plane at every position. Based on the projection principles of the camera and projector, unified phase values in this process were extracted enabling the PTH relationship to be determined easily. This makes the subtraction of a reference phase, as used in traditional FPP, is no longer necessary. Second, distorted fringe patterns reflected by target object are captured, and height values are calculated based on the obtained PTH relationship. Finally, by calibrating the intrinsic and extrinsic parameters of the camera, the 3D coordinates (xw,yw,zw) of object surface can be determined accordingly. The proposed method was verified by experiments, which demonstrate the validity and accuracy of the proposed method.