Two-neighbor-wavelength phase-shifting approach for high-accuracy rapid 3D measurement

This paper presents a two-neighbor-wavelength fringe projection approach for high-accuracy fast 3D measurement. Different from the traditional two-wavelength fringe projection approach, the proposed approach encodes four fringe images, wherein two are short-wavelength images and the other two are long-wavelength images, which significantly reduces the time for the camera to collect images. And the short-wavelength pattern has one more fringe period than the long-wavelength pattern, which decreases the frequency ratio and extends the noise tolerance. Through a concise algorithm, the one-period reference phase and multiple periods wrapped phase are extracted simultaneously. The wrapped phase is unfolded through phase stairs derived from the reference phase, so as to retrieve the unwrapped phase. Both static and dynamic experiments demonstrate the effectiveness and superiority of our method.