Static Evaluation of One Shot 3D Surface Imaging using Digital Colored Fringe Projection Technique

This research developed an alternative to grayscale Phase Shifting Interferometry for 3D surface measurement by utilizing three channels color fringe. As it has been known, grayscale PSI has limitation on dynamic object measurement due to its multi-frame term. By utilizing digital color image, it merely needs a single fringe projection making it possible to obtain faster data acquisition. However, each channel of the recorded image has different intensity range due to optical system's non-linearity that would significantly affect the quality of the reconstruction. Therefore, normalization is urgently needed before performing phase computation. In this study, the normalization was performed using Isotropic N-Dimensional Fringe Normalization (INFPN) based on Hilbert Transformation, while the phase processing includes extraction using 3-step PSI and global phase unwrapping. Experiments are conducted to evaluate RGB fringe performance compared to the grayscale 3-step PSI and grayscale single frame Fourier Transform Profilometry (FTP). The results show that RGB fringe can produce a fairly good reconstruction with the measurement error of less than 6% compared to the grayscale 3-step PSI on static evaluation. It also gives far better quality of reconstruction than the grayscale single frame FTP.