High-quality binary fringe generation via joint optimization on intensity and phase

There have been active studies on optimized dithering techniques to improve 3D shape measurement quality with defocused projectors. These techniques optimize the fringe quality in either phase domain or intensity domain according to their objective functions. Phase based optimization is direct and effective, but is sensitive to projector defocus levels. Intensity based optimization is robust to projector defocus levels, but it does not fully improve the phase quality. This paper presents a joint optimization technique to combine the merits of both the intensity and phase based optimization, which includes a pre-intensity optimization and a further optimization based on the synthesized error function. Then this technique is implemented in two frameworks, the whole-fringe optimization and the best-patch optimization, to generate binary fringe patterns. Both simulations and experiments show that the proposed technique can generate binary fringe patterns with high phase quality and robustness to projector defocus levels.