3-D Structured Light Scanning With Phase Domain-Modulated Fringe Patterns

Abstract

Existing 3D structured light scanning methods require a high number of images (multi-frequency phase shifting, MF-PS) or embed signals in the space domain (space domain modulation phase shifting, SDM-PS) to conduct phase unwrapping. These methods are either movement sensitive (for MF-PS) or low in accuracy (for SDM-PS). In this work, a new 3D structured light scanning method is proposed to use the theoretical minimum of three images only. Unlike existing methods that directly embed signals in the space domain, the assistance signals are modulated in the phase domain of phase shifting images, inspired by the phase-shift keying (PSK) theory. Phase calculation in the proposed phase domain modulation phase shifting (PDM-PS) method is independent of embedded assistance signals. The signal to noise ratio (SNR) of phase codewords and the accuracy of phase unwrapping and 3D reconstruction are well retained. Experimental results demonstrated that the proposed PDM-PS method using only three images was able to achieve comparable 3D measurement accuracy as the traditional MF-PS method (3 images vs. 9 images, 0.03 mm vs. 0.02 mm); and both using three images, the proposed PDM-PS method outperformed the traditional SDM-PS method in terms of measurement accuracy (0.03 mm vs. 0.07 mm).