Fast phase-based stereo matching method for 3D shape measurement

Three dimensional (3D) shape-measurement systems combining fringe projection and stereo vision utilize phase for dense stereo matching. However, projection of orthogonal fringe patterns and computation of curved epipolar lines due to lens distortion has made traditional phase-based stereo matching time-consuming. This paper presents a phase-based stereo matching method that takes advantage of epipolar line rectification and transforms bi-stereo geometry into epipolar standard geometry. Using phase-shifting techniques to compute phase, stereo matching is simplified by searching for the closest phase along horizontal epipolar lines. Compared with the traditional method, this method shortened the stereo matching time by 20 percent. In 3D reconstruction of a plane with high flatness, the 3D shape measurement accuracy was demonstrated to be 0.0178mm. Thus, this method is suitable for applications that require fast speed and high accuracy.