Phase unwrapping method combining hilbert transform and gray code
Traditional Gray-code assisted four-step phase shifting phase unwrapping method requires projection of four stripe patterns,but the reconstruction accuracy is not high due to factors such as environmental noise and defocus-ing of the projector.In order to improve the efficiency and accuracy of three-dimensional reconstruction,a phase un-wrapping method combining Hilbert transform and Gray code is proposed.First,the cosine component is obtained u-sing the acquired sine stripes image and the background light intensity image,and then the cosine component is con-volved with the shock response using the Hilbert transform.Shifting the phase by π/2 while keeping the original fre-quency and amplitude unchanged.Finally,the absolute phase of the measured object is solved by using the phase or-der obtained by Gray code decoding.In addition,the tripartite phase unwrapping method(Tri-PU)is used to elimi-nate the edge hopping error in the process of Gray code phase unwrapping.The experimental results show that the ac-curacy of the proposed method is 0.045 mm in the reconstruction of high precision standard ball,and the reconstruc-tion accuracy is high.The projection stripe images are reduced from four to two,which improves the projection effi-ciency.
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