Unambiguous 3D measurement from speckle-embedded fringe.

This paper proposes a novel phase-shifting method for fast, accurate, and unambiguous 3D shape measurement. The basic idea is embedding a speckle-like signal in three sinusoidal fringe patterns to eliminate the phase ambiguity, but without reducing the fringe amplitude or frequency. The absolute depth is then recovered through a robust region-wise voting strategy relying on the embedded signal. Using the theoretical minimum of only three images, the proposed method greatly facilitates the application of phase shifting in time-critical conditions. Moreover, the proposed method is resistant to the global illumination effects, as the fringe patterns used are with a single high frequency. Based on the proposed method, we further demonstrate a real-time, high-precision 3D scanning system with an off-the-shelf projector and a commodity camera.