LUT-based phase error compensation method for large-step phase-shifting algorithm in DLP4500-based FPP system.

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As a low-cost professional digital light projection device, the DLP4500 have been widely applied in fringe projection profilometry (FPP), for both laboratory and practical application. However, our recent experiments revealed a new hardware-induced projection instability when the projection pattern data exceeds its buffer capacity (48 bits). This phenomenon undermines the measurement accuracy advantage of the phase-shifting (PS) algorithms with large number of shifting steps, and eventually leads unwanted and complicated error to 3D reconstruction. In this paper, we experimentally investigate the new hardware-induced phase error and proposed a LUT-based phase error compensation method. In this method, a standard plate with a precision manufactured plate is used as the standard reference for the phase error evaluation, where an ideal plane fitting and the projector pixel reprojection process are introduced to generate the ideal reference phase. Comprehensive experiments are conduct to verify the stability of the proposed method in LUT creation. Comprehensive experiments are conduct, and the results show that (i) the method works creates LUTs stably at different plate positions, (ii) the plate with regular manufacturing accuracy (not exceeding 0.01 mm) can meet the application requirements of the proposed method. Both quantitative and qualitative experimental results successfully verify the effectiveness of proposed method in LUT creation and phase error reduction.