Three-dimensional shape measurement apparatus and method for eliminating2pi ambiguity of moire principle and omitting phase shifting means

Abstract

A three-dimensional (3-D) shape measurement method using a Moire measurement principle and a Stereo vision measurement principle is provided. The method comprises; a first step to detect candidate points and 3D positions of the candidate points in world coordinates which are identical results from typical Moiré technique by using a pattern projector, which adjusts a pitch of a fringe pattern and projects the fringe pattern to a measurement object, and a first camera, which detects a modulated fringe pattern caused by shape of the object, by means of obtaining candidate points by comparing a reference fringe pattern to the modulated fringe pattern and calculating 3D positions at an arbitrary point on an image captured from the first camera; a second step to determine a final matching point among the candidate points detected from the first step by using the Stereo vision technique with the first and the second cameras, by means of projecting the 3D positions of the candidate points to an image plane of the second camera based on a camera matrix of the second camera, comparing intensity value of a projected point in the image plane of the second camera to intensity value of given point in the image plane of the first camera, and judging whether the candidate point is matched with an arbitrary point by using the stereo vision criteria; and a third step to measure the depth value of the arbitrary point by using the resultant value of the final matching point, which was determined at the second step. Therefore, the error of 2π ambiguity of the typical Moire principle is eliminated, and thus 3-D shape information can be more rapidly and accurately measured