Efficient phase unwrapping for moiré fringes via BM3D denoising and the Fourier-domain Poisson equation solution

Moiré deflectometry has been widely applied in complex flow field measurements owing to its non-contact nature and strong resistance to interference. An accurate and efficient phase unwrapping strategy for moiré deflectometry is proposed in this paper. First, the noise was estimated using a wavelet transform, followed by BM3D denoising to enhance robustness. Based on this, the denoised wrapped phase is obtained. Subsequently, the Poisson equation was solved in the frequency domain using the Fourier transform to achieve efficient phase reconstruction. Comparative evaluations were carried out in simulated flow fields with different structures and noise intensities. The results demonstrate that the method maintains high unwrapping accuracy while significantly reducing computational cost compared with the multigrid method. Finally, our proposed method is applied to three real flow fields. In a word, the effectiveness of the method expands the application prospects of moiré deflectometry in the measurement of complex flow fields.