Fig. 1. Schematic of 3D imaging technique based on phase-shift fringe analysis

Fig. 2. Main optimization approaches of real-time 3D measurement

Fig. 3. Installation diagram of fast projection equipment. (a) Laser interference fringe measurement system^[33]; (b) light source stepping method phase shift projection equipment^[34]; (c) array projection equipment^[35]; (d) rotating projection measurement system^[36]; (e) rotating structured light sequence projection equipment^[38]; (f) 5D hyperspectral imaging system^[40]; (g) rotating projection measurement system^[43]; (h) MEMS galvanometer scanning projection measurement system^[45]

Fig. 4. Fringe binarization. (a) Binary fringes; (b) local magnification; (c) binary fringe defocusing effect

Fig. 5. Schematic of phase unwrapping guided by fringe embedding auxiliary information. (a) De Bruijn sequence embedding four-step phase shift fringes^[67]; (b) periodic signal embedding four-step phase shift fringes^[68]; (c) speckle signal embedding three-step phase shift fringes^[69]; (d) phase encoding embedding four-step phase shift fringes^[21]

Fig. 6. Gray code aided phase shift technique^[72-73]. (a) Projected phase shift fringes; (b) projected Gray code fringes; (c) decoding process of the Gray codes; (d) decoding process of the complementary Gray codes

Fig. 7. Schematic of improving Gray code efficiency. (a) Cyclic complementary Gray code aided phase shift method^[74]; (b) shifting Gray code aided phase shift method^[75]; (c) regional division phase unwrapping method and Gray code multiplexing coding strategy^[76]; (d) ternary Gray code aided phase shift method^[77]

Fig. 8. Schematic of multi-frequency fringes information multiplexing. (a) Dual-frequency composite phase shift method^[79,8]; (b) 3+2 phase shift method^[80,8]; (c) 2+2 phase shift method^[81,8]

Fig. 9. Schematic of multi-view stereo phase unwrapping and depth constraint^[85]

Fig. 10. Real-time 3D shape measurement and motion error elimination method^[100]. (a) Processing flow; (b) 3D reconstruction sequence

Fig. 11. Some results of real-time 3D reconstruction