3D Shape Reconstruction Algorithms for Modulation Measuring Profilometry with Synchronous Scanning

Abstract

The three-dimensional profilometry based on structured light triangulation can achieve relatively high precision, but the offset angle formed by the optical axis of projection system and observation system can cause shadow and occlusion. The measurements from two directions and image stitching technology are needed. Different from the triangulation methods, the modulation measuring profilometry is based on vertical measurement theory. In its measuring system, the optical axes of projection and observation are coaxial, which avoid the shadow and occlusion problem in the triangulation methods. A modulation measuring profilometry with auto-synchronous phase shifting and vertical scanning and the reconstruct algorithm are studied. The features of scanning fringes are analyzed, and the features of several algorithms about modulation extraction and 3D shape reconstruction are introduced and compared. Experiments indicate that choosing the proper algorithm can achieve better measuring accuracy of 0.19 mm standard deviation in the measuring range of 115 mm while measuring a 120 mm×120 mm testing plane, under vertical measuring mode.