Fig. 1. Correspondence among wrapped phase, unwrapped phase, and phase order

Fig. 2. Correspondence between Gray code and phase

Fig. 3. Wrapped phase and intensity of sinusoidal stripe after amplitude modulation. (a) Wrapped phase; (b) corresponding intensity of sinusoidal stripe

Fig. 4. Mean error of the unwrapped phase in different periods T

Fig. 5. Correspondence between the number of phase periods and De Bruijn sequence

Fig. 6. Four computer generated projection patterns

Fig. 7. Flowchart of unwrapping phase

Fig. 8. Incomplete period case. (a) Occluding falling edge, only left rising edge; (b) occluding rising edge, only left falling edge

Fig. 9. Symbol judgment error caused by the maximum value being blocked

Fig. 10. A mask. (a) Object to be tested; (b) fringe image captured by camera; (c) wrapped phase; (d) unwrapped phase

Fig. 11. 3D point cloud results. (a) Frontal result; (b) profile result

Fig. 12. Two water pipes placed front and back. (a) Object to be tested; (b) wrapped phase

Fig. 13. Phase unwrapping. (a) Wrapped phase; (b) phase order; (c) unwrapped phase

Fig. 14. Comparison of the reconstruction results between Gray code combined with phase-shifting method and the proposed method

Fig. 15. Reconstruction results of flat plate. (a) Reconstruction result of Gray code combined with phase-shifting method; (b) reconstruction results of multi-frequency heterodyne; (c) reconstruction results of proposed method