Phase correction method for dynamic 3D measurement based on fringe projection

An additional phase shift is produced when the 3D shape of dynamic scene is measured by phase shifting method. The phase distribution measured by traditional method is distorted and the recovered 3D shape is distorted as well. The Gerchberg iteration algorithm and the windowed Fourier assisted phase shifting method were proposed to reduce the distortion. The main ideal of these methods is to accurately estimate the phase shift between two fringe patterns. The accuracy of phase shift estimation is low near the edge where the frequency of fringe changes suddenly. We proposed a method to increase the accuracy of phase shift estimation. The edge of frequency sudden change is found out and then the fringe pattern is divided into different regions. The Gerchberg iteration algorithm is adopted to extend the fringe to outside of every region. The windowed Fourier analysis is adopted to estimate phase of every region and then the phase distribution of whole pattern is obtained. The phase shift between two fringe patterns is obtained by subtracting the estimated phase of first pattern from that of second pattern. Finally, the accurate phase distribution is obtained from the fringe patterns and the estimated phase shifts by least square method. The comparative experiments were carried out to evaluate the proposed method. The experimental results show that the accuracy of measured phase by proposed method is higher than that by windowed Fourier assisted phase shifting method.