Windowed Fourier Transform For 3-D Shape Measurement

Optical 3-D profilometry has been widely used for machine vision, industry monitoring, reverse engineering, biomedicine, real object visualization etc. Fourier transform profilometry based on fringe projection is one of the non-contract full-field 3-D measurement methods. This method requires only one frame of deformed fringe pattern reflected by a diffuse object surface and have higher precision, so much attention of researchers was payed to it. But in FTP, Fourier transform and filtering operation are needed, so how to eliminate frequency aliasing and improve measurement precision is always the key problem for FTP application.Because of the local analysis characteristic of Windowed Fourier transform(WFT), it has been used in optical 3-D shape measurement. The major idea is that: the spectrum of partial fringes formed by scanning the whole fringe pattern by a window function is simpler and less-aliasing than that of a whole fringe. A WFT method is introduced to retrieve the phase distribution caused by object height variety, which has been modulated into deformed fringe, from spatial fringe pattern directly. Basing on this method, the filtering operation carried out to obtain the foundational frequency of each local fringe pattern is not necessary, so it...