Spatial-fringe-modulation-based quality map for phase unwrapping.

The quality-guided algorithm is a method widely used in phase unwrapping. The algorithm uses a quality map to guide its unwrapping process, and its validity depends on whether the quality map can truly reflect phase quality. In fringe projection surface profilometry, discontinuous surface structure, low surface reflectivity, and saturation of the image-recording system are sources of unreliable phase data. To facilitate the unwrapping process, we demonstrate an accurate quality map based on spatial fringe modulation, which is extracted from a single fringe pattern. Compared with temporal fringe modulation, the new criterion is more sensitive to spatial structure changes and less dependent on illumination conditions.