Octal gray-code phase unwrapping for high-speed fringe projection profilometry

Abstract

The speed of a fringe projection profilometry system is of great importance for the measurement of dynamic objects. The previous quaternary gray-code phase unwrapping method uses only five patterns to recover an absolute phase which is suitable for high-speed measurement. However, this method requires a pre-knowledge of the minimum depth and it limits the object to move in a small range of depth. To extend the measurement range, we proposed an octal gray-code phase unwrapping method, in which five patterns are required. We apply this method to different objects and analysis the experiment results. This method can recover a good-quality phase map for sample objects, while its performance is decreased when the object is complex or with an improper defocusing level.