An Improved Phase Unwrapping Method Based on Geometric Constraints

Abstract

In the field of three-dimensional measurement of structured light, the phase unwrapping method based on geometric constraints has the characteristics of high precision. This method does not need to acquire additional marking images, nor does it need to use expensive hardware equipment, and can achieve rapid and accurate phase unwrapping with the help of a reference plane, which can meet the practical requirements of fast and high precision 3D measurement. However, the 3D measurement method based on geometric constraints has a problem of limited measurement depth, and the maximum measurement depth range is within the phase domain of 2π . If the height of the measured object is beyond this range, normal phase unwrapping cannot be performed. In this paper, the target image is segmented according to the boundary discontinuous feature of the region beyond the measurement range, and then the relative phase unwrapping algorithm based on modulation intensity sorting is used for this region. Finally, the correct absolute phase information of the measured target is recovered. Experiments show that this method can not only increase the depth of measurement but also has better robustness for low phase mass region. The validity and correctness of the proposed method are verified by experiments.