This paper introduces a novel real-time, high-dynamic-range (HDR) three-dimensional (3D) shape measurement method using a RGB camera. The proposed method takes advantage of two effects to realize HDR 3D fringe acquisition for 3D shape measurements: (1) the different responses of a RGB camera’s three channels to a single color light source can be utilized to produce fringe images with different intensity levels; (2) the projector’s dark time can be utilized to produce bright versus dark intensity contrast if bit-wise binary patterns are used. Experiments demonstrate the real-time capabilities of the proposed method by dynamic 3D shape measurements (with a maximum camera frame rate of 166 Hz). Given that a bit-wise defocused binary pattern projection is adopted, the proposed HDR method has the potential for high-speed applications if a high-speed color camera is present.

The recently proposed binary defocusing technique has brought speed breakthroughs for three-dimensional (3D) shape measurement with a digital fringe projection system. Despite this, motion-induced phase error is still inevitable due to the multi-shot nature of the phase-shifting algorithm. To alleviate this problem, this paper proposes a motion-induced error reduction method by taking advantage of additional temporal sampling. Particularly, each illuminated fringe pattern will be captured twice in one projection cycle, resulting in two sets of phase shifted fringe images being obtained. Due to the mechanism of binary defocusing projection, the motion-induced phase error could be effectively separated from the fixed phase shift value by evaluating the difference between the two phase maps. Based on this, an iterative compensation strategy is further applied to compensate the phase error until high-quality phase maps are generated. Meanwhile, different synchronization schemes are also proposed and tested to evaluate the error compensation effects. Both simulation and experiments demonstrated that the proposed methods can substantially reduce motion-introduced measurement errors. Since defocused 1-bit binary patterns are utilized to bypass rigid camera-projector synchronization, this method has potential for high-speed applications. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement