Fig. 1. Flowchart of real-time 3D imaging based on ROI projection and phase estimation. The green and orange arrows indicate the processing flow for low- and high-frequency fringe patterns, respectively.

Fig. 2. Real-time phase estimation network structure. (a) Outer structure of PE-Net, loss function design, and training process; (b) internal structure of the phase estimation module; (c) internal structure of the lightweight network.

Fig. 3. NonBt1d module, downsampling module, dilated convolution module, and upsampling module within the lightweight network.

Fig. 4. Flowchart of the MHPU method. (a) Equivalent phase with the phase difference of low- and high-frequency fringe; (b) unwrapped equivalent phase assisted by a reference plane; (c) unwrapped phases of low frequency and high frequency.

Fig. 5. Depth limitation of MHPU.

Fig. 6. Two fringe projection strategies. (a) Normal fringe projection. (b) ROI fringe projection.

Fig. 7. Comparison of two fringe projection strategies. (a) Generated fringe pattern (top left) and perspective view (top right) of normal fringe projection. (b) Corresponding results of ROI fringe projection.

Fig. 8. Measurement results of standard spheres using three-step PSP and two projection strategies. (a), (b) Fringe patterns of two projection strategies. (c),(d) 3D reconstruction results of two projection strategies.

Fig. 9. Train and validation loss curves of PE-Net.

Fig. 10. 3D reconstruction results of the David sculpture. (a) Ground truth. (b) Feng’s method; (c) UNet method; (d) NAS method; (e) proposed PE-Net.

Fig. 11. Error distributions of the David sculpture. (a) Feng’s method; (b) UNet method; (c) NAS method; (d) proposed PE-Net. (e)–(h) Localized enlarged images of the dashed-boxed regions corresponding to each method.

Fig. 12. 3D reconstruction results and error values of the standard spheres. (a) Feng’s method; (c) UNet method; (e) NAS method; (g) proposed PE-Net. (b), (d), (f), (h) Corresponding depth error distributions and error values.

Fig. 13. Real-time 3D reconstruction results (Visualization 1). (a), (b) Measurement scene comprising a stationary David and a rotating Nike sculpture. (c)–(f) 3D point cloud of different frames.