Phase unwrapping is the decisive factor for achieving dimensional accuracy in phase-shifting profilometry, yet unavoidable phase jumps occur at discontinuities. Existing dual-frequency heterodyne techniques suffer from a narrow measurement range and overly coarse projected fringes due to grating superposition requirements, leading to large errors when scanning objects with hole-like features. To address these issues, this paper proposes an edge-oriented phase-unwrapping error-compensation method based on fringe projection phase profilometry. First, the wrapped phase of the measured object is acquired via phase-shifting profiling. The wrapped phase map is then smoothed at multiple scales using Gaussian filters, and parallel Canny edge detection combined with phase gradient thresholding is applied to comprehensively capture both coarse and fine discontinuities. Morphological closing fills in breakpoints, followed by skeleton thinning and connectivity reconstruction to generate an edge band of defined width. Within this band, edge-preserving smoothing is performed using guided filtering or bilateral filtering, and the result is fused with the original phase through Gaussian weighting based on the distance to the skeleton. Finally, an ordered multi-frequency heterodyne unwrapping restores the absolute phase, maximally preserving true discontinuities while effectively correcting noise and detection errors. Experiments show that this method overcomes edge-induced phase jumps—with jump-error correction rates exceeding 96.7%—exhibits strong noise resilience under various conditions, and achieves measurement precision better than 0.06 mm.

In dual-frequency heterodyne structured-light 3D measurement, fringe-order misjudgment often occurs near object edges, hole boundaries, and local low-reliability regions, which may further lead to absolute phase jumps and abnormal 3D reconstruction results. To address this problem, this paper proposes a phase-unwrapping method based on region-of-interest (ROI) constraint, coarse estimation using the synthetic wrapped phase, dual-frequency consistency residual optimization, and local spatial regularization. The method first automatically extracts the target ROI using a binary mask, thereby excluding invalid background regions and reducing unnecessary computation. A synthetic wrapped phase is then constructed from the two wrapped phases, and a coarse absolute phase is obtained using the long synthetic period. The initial fringe order is estimated by rounding rather than the conventional floor operation, reducing systematic fringe-order misjudgment near integer boundaries. On this basis, a dual-frequency consistency residual is constructed to perform local candidate search and reliability evaluation. Reliable-anchor constraints and local spatial regularization are subsequently introduced to correct abnormal fringe orders in low-reliability regions and suppress error propagation near edges and holes. Experimental results on objects with complex boundaries show that the proposed method effectively suppresses phase jumps and improves the continuity of the unwrapped phase and reconstructed point cloud. Accuracy verification using a three-layer step block showed mean height errors of 0.0230, 0.0320, and 0.0370 mm for the three layers, respectively, with corresponding standard deviations of 0.00852, 0.00880, and 0.00963 mm, all below 0.01 mm. These results demonstrate that the proposed method can effectively suppress fringe-order-induced phase jumps while maintaining high accuracy and stability in structured-light 3D reconstruction.