[OPTICAL REVIEW Vol. 19, No. 6 (2012) 444-450]
© 2012 The Japan Society of Applied Physics

Phase Unwrapping Algorithm Based on Singularity Compensation for Three-Dimensional Shape Measurement

Samia HESHMAT1,2*, Satoshi TOMIOKA3, and Shusuke NISHIYAMA3

1Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan
2Aswan Faculty of Engineering, Aswan University, Aswan 81542, Egypt
3Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan

(Received May 28, 2012; Accepted August 31, 2012)

Three-dimensional (3D) imaging continues to attract much research interest for its wide applications. In 3D shape measurement, the phase carries information about the object. However, phase mapping is ambiguous as the extracted phase is returned in a form that suffers from 2π phase jumps. In this case, the phase data must be unwrapped to be fit for use. Furthermore, sometimes the presence of noise in the measured data, in which many singular points (SPs) are found, makes general phase unwrapping algorithms fail to produce accurate unwrapped results. For this reason, we propose a new phase unwrapping method for dynamic 3D shape measurement. The new algorithm is based on compensating the singularity of discontinuity sources. It uses direct compensators for adjoining SP pairs and uses rotational compensators for other SP pairs. The proposed algorithm has been evaluated and compared with past phase unwrapping methods. Results show that the proposed method gives satisfactory unwrapped results with a low computation time.

Key words: 3D shape measurement, phase unwrapping, fringe analysis

*E-mail address: samia@athena.qe.eng.hokudai.ac.jp