Reference image based phase unwrapping framework for a structured light system.

A novel real-time full-field phase unwrapping framework is proposed for the one-projector and one-camera structured light system. In this framework, only four patterns (including three fringe patterns and a binary speckle pattern) are required to measure the absolute 3D shape of the targets. We use the structured light system to capture four images of a nearly planar target (e.g. wall), of which the speckle image is taken as the reference image, and the corresponding absolute phase map is computed and stored, before measuring. So each pixel in the reference image can be mapped to an absolute phase value. In this way, if we can create the correspondences between the current and the reference speckle images in the process of measurement by using a matching algorithm, we can directly map the absolute values for the pixels of the current image. The mapped absolute phases can be used to determine the period of the relative phases. The experimental results verified the effectiveness and efficiency of the proposed framework. On a consumer-grade GPU (Nvidia GTX1060), our method can run at 187 fps.