Comparison of Multi-frequency Phase Unwrapping Algorithm for Shape Measurement Using Digital Fringe Projection

As technology development, projected digital fringe pattern is widely used in measuring three-dimensional (3D) shape, even in the presence of surface discontinuities. This paper investigates the reliability and accuracy of two multi-frequency phase unwrapping algorithms by experimental means. The first, which unwraps through a sequence of phase maps produced with exponentially change in spatial frequency with time, is found to be less robust and accuracy than the second, which only use three different frequency to beat new frequency for unwrapping the phase. Through experiment, the best frequency, adjacent ratio for the first method and frequency difference for the second method are proposed for the high efficiency and accuracy measurement.