Multiple views merging from different cameras in fringe-projection based phase-shifting method

摘要

This paper discusses issues related to accurate measurement using multiple cameras with phase-shifting techniques. Phase-shifting methods have been widely used in industrial inspections due to high accuracy and excellent tolerance to surface finish. But so far, most such systems use only one camera. In our applications to inspect manufactured part with complex shapes, one camera cannot capture the whole surface because of occlusions, double bounced light, and the limited dynamic range of cameras. Multiple cameras have to be used and the data from different cameras must be merged together. Because different cameras have individual error sources when a part is to be measured, it is a challenge to obtain the same shape, in the same 3D coordinates system from all cameras without data manipulation such as iterative registration. This paper addresses this challenge of data registration. The error sources are analyzed and demonstrated and several paths for error reduction are presented. Experiment results show the significant improvement obtained.