Fast 3D Scanning with Automatic Motion Compensation (Stereo approach)

An intrinsic problem of phase-shifting methods is the inability to deal with blurred images caused by motion of the scanned object or person. There are a lot of initiatives or modifications performed to the original structured light method to support scanning of objects in motion. Please refer to Zhang's paper "Recent progress on real-time 3D shape measurement ... - Song Zhang" mentioned in the previous post. There Zhang cover some techniques to deal with blur by motion images with acceptable results.

In the paper presented below, the authors have decided to replace the unwrap phase of the structured light method by an stereo-based approach to have the same problem of correspondence solved but by a different mechanism. They argued that the unwrapping phase does not solve the absolute phase and that if two surfaces been scanned have a discontinuity of more than 2pi then no method based on phase-shifting will correctly unwrap these two surfaces to each other.


* Fast 3D Scanning with Automatic Motion Compensation - Thibaut Weise, Bastian Leibe and Luc Van Gool

Abstract
We present a novel 3D scanning system combining stereo and active illumination based on phase-shift for robust and accurate scene reconstruction. Stereo overcomes the traditional phase discontinuity problem and allows for the reconstruction of complex scenes containing multiple objects. Due to the sequential recording of three patterns, motion will introduce artifacts in the reconstruction. We develop a closed-form expression for the motion error in order to apply motion compensation on a pixel level. The resulting scanning system can capture accurate depth maps of complex dynamic scenes at 17 fps and can cope with both rigid and deformable objects.