Fig. 1. Dual-frequency method

Fig. 2. Three-frequency method

Fig. 3. Symmetrical phase and wrapped phase

Fig. 4. Window matching

Fig. 5. Measurement grating diagrams. (a)-(d) High-frequency four-step phase shifting diagram; (e)-(f) symmetrical fringe diagram; (g)-(j) low-frequency four-step phase shifting diagram; (k)-(n) single-frequency four-step phase shifting diagram

Fig. 6. Phase results. (a) Wrapped phase; (b) symmetrical phase; (c) fringe order

Fig. 7. Comparison of absolute phase and error. (a)-(c) Absolute phase; (d)-(f) phase error

Fig. 8. Three-dimensional point cloud. (a) Dual-frequency method; (b) three-frequency method; (c) proposed method