Influence of sampling on composite structured light pattern

To study the influence caused by sampling, here the method, in which the pectinate function was introduced to sample the fringe patterns, was adopted. Basing the knowledge of the convolution theorem, the phase error caused by sampling in practical composite Fourier-transform profilometry (CFTP) was discussed along two directions. The criterions for the selection of sampling frequency are derived and the results indicate that to avoid the spectrum overlapping, the sampling frequency along the phrase variation direction must be at least four times as the fundamental frequency, and along the orthogonal direction it must be at least three times as the larger frequency of the two carrier frequencies. The computer simulations and practical experiments verified the theories.