Phase-domain modulated hybrid phase-shifting structured light based efficient 3D measurement

Phase-shifting profilometry (PSP) measurement technology remains a research hotspot in 3D imaging. However, existing PSP methods require projecting additional patterns, which limits measurement space, or involves compressing fringe amplitudes to eliminate phase ambiguity. These practices result in reduced measurement efficiency and robustness. To overcome these challenges, we present a novel phase-domain modulated hybrid phase-shifting (PDM-HPS) structured light 3D measurement approach to solve the phase error of existing spatialdomain modulated phase-shifting (SDM-PS) methods without imposing additional pattern or space constraints. The method integrates phase-shifting speckle and phase-shifting fringe methodologies to create a hybrid phaseshifting coding pattern. In the decoding phase, the offset speckle phase is detected and corrected by the lowprecision phase extracted in the frequency domain. The separation of binary speckle and high-precision wrapped phase is realized. Ultimately, an efficient binary speckle-aided stereo phase matching process is employed to achieve unambiguous phase unwrapping. We test the PDM-HPS method in multiple complex real-world scenarios using binocular structured light systems, and compare its accuracy and efficiency with three existing advanced methods. The qualitative and quantitative results show that the proposed method can achieve the measurement accuracy similar to that of the multi-frequency (MF) method by using only 1/3 projection patterns.