Fig. 1. Normalized absolute phase diagrams (each row represents a method of phase decompression, with noise increasing from left to right). (a)--(d) Multi-frequency(hierarchical) phase unwrapping method; (e)--(h) negative exponential fitting method; (i)--(l) multi-wavelength (heterodyne) method; (m)--(p) multi-wavelength(heterodyne) method based on fringe location

Fig. 2. Error trend diagram of four algorithms at different noise levels

Fig. 3. Normalized phase unwrapping results(the first row represents the value of the entire surface, and the second row corresponds to the expansion of the first row result in 800th row). (a)(e) Multi-frequency(hierarchical) phase unwrapping method; (b)(f) negative exponential fitting method; (c)(g) multi-wavelength (heterodyne) method; (d) (h) multi-wavelength(heterodyne) method based on fringe location

Fig. 4. Three-dimensional reconstruction diagrams. (a) Deformed fringe pattern; (b) wrapped phase map; (c) unwrapped phase map of negative exponential fitting; (d) reconstruction by multi-frequency(hierarchical) phase unwrapping method; (e) reconstruction by negative exponential fitting method; (f) reconstruction by multi-wavelength (heterodyne) method; (g) reconstruction by multi-wavelength (heterodyne) method based on fringe location

Table 1. Error comparison of four unwrapping algorithms