Polarization and Phase-Shifting for 3D Scanning of Translucent Objects

Abstract

Translucent objects pose a difficult problem for traditional structured light \n3D scanning techniques. Subsurface scattering corrupts the range estimation in \ntwo ways: by drastically reducing the signal-to-noise ratio and by shifting the \nintensity peak beneath the surface to a point which does not coincide with the \npoint of incidence. In this paper we analyze and compare two descattering \nmethods in order to obtain reliable 3D coordinates for translucent objects. By \nusing polarization-difference imaging, subsurface scattering can be filtered \nout because multiple scattering randomizes the polarization direction of light \nwhile the surface reflectance partially keeps the polarization direction of the \nillumination. The descattered reflectance can be used for reliable 3D \nreconstruction using traditional optical 3D scanning techniques, such as \nstructured light. Phase-shifting is another effective descattering technique if \nthe frequency of the projected pattern is sufficiently high. We demonstrate the \nperformance of these two techniques and the combination of them on scanning \nreal-world translucent objects.