Fig. 1. Optical path used in projection fringe method

Fig. 2. t and k when T=10 and p=30 pixel

Fig. 3. Effect of special point on coding unwrapping method. (a) Incorrect decoding when T=10; (b) correct decoding when T=31/3

Fig. 4. Effect of noise on coding unwrapping method. (a) Distribution of k; (b) distributions of σ_lim and I'_N+1

Fig. 5. Simulation results. (a) Decoding results of conventional method and proposed method; (b) anti-noise effects of three discrimination methods

Fig. 6. Decoding results by proposed method in case of large noise. (a) Error decoding position and corresponding NTI index; (b) neighborhood correction result

Fig. 7. Test experiment. (a) Experimental setup; (b) measured objects

Fig. 8. Flow chart of improved phase-shift coding method

Fig. 9. Experimental process and results. (a) Fringe projecting to measured object; (b) wrapped phase of measured object; (c) distribution of k; (d) unwrapping phase; (e) 2D distribution of phase difference; (f) result by proposed decoding method; (g) result by decoding method in Ref. [14]