Frequency Shift Method: A Technique for 3-D Shape Acquisition in the Presence of Strong Interreflections

This article presents a structured light codification technique called frequency shift method which is especially designed for scenes containing strong interreflections. The method works by projecting multiple sine wave patterns having different frequencies. While the phase shift method associates a phase to each column of the projector, in the proposed codification, each column of the projector is uniquely encoded by the frequencies used and explicitly decoded using the discrete Fourier transform. This encoding allows the method to recover all the projector columns that contribute to a camera pixel's observed intensity. An energy minimization is then used to separate direct and indirect illuminations. Objects presenting diffuse and specular interreflections are considered, and our experimental results illustrate the efficiency of our method compared with previously proposed methods.