High-accuracy 3D measurement technique without phase unwrapping based on fringe projection

In the existing binocular fringe projection methods, the continuous phase is commonly employed for performing 3D scene reconstruction. However, this method has phase ambiguity issues that require the addition of patterns or the utilization of embedded signals to be solved. However, this approach not only leads to the introduction of cumbersome steps but also fails to accurately reconstruct objects without obvious features. To effectively overcome these challenges, an active stereo 3D measurement method was proposed that eliminated the need for phase unwrapping. More specifically, the proposed method first applied binary processing to the wrapped phase map, followed by extracting phase order lines, and assigning symbolic labels to the phase intervals between them, accomplishing thus rough matching. Finally, based on the region block matching, the phase values were used to refine the disparity map. The proposed method was evaluated using a standard sphere with a diameter of 60 mm, and the root-mean-square error of the proposed method is 0.053 mm.