Fig. 1. The flowchart of noisy fringe image phase acquisition based on U-NET

Fig. 2. Different stages of high-frequency noisy fringe images restoration. (a) High-frequency noisy fringe image of the doll cat; (b) High-frequency noisy fringe image of the combined object; (c) The arc tangent function numerator of the doll cat; (d) The arc tangent function numerator of the combined object; (e) The arc tangent function denominator of the doll cat; (f) The arc tangent function denominator of the combined object; (g) The absolute phase of the doll cat; (h) The absolute phase of the combined object

Fig. 3. Comparison of the phase error between deep learning and traditional method. (a) The error between the true value and the absolute phase of the doll cat recovered by the traditional three-step phase shift method; (b) The error between the true value and the absolute phase of the doll cat using deep learning; (c) The error curve of the true value and the absolute phase of the doll cat recovered by the two methods; (d) The error between the true value and the absolute phase of the combined object recovered by the traditional three-step phase shift method; (e) The error between the true value and the absolute phase of combined objects using deep learning; (f) The error curve of the true value and the absolute phase of the combined object recovered by the two methods

Fig. 4. Comparison of 3D reconstruction results under different methods. (a) 3D reconstruction result of the doll cat restored by the method in this paper; (b) 3D reconstruction result of dolls cat restored by traditional methods; (c) The true 3D reconstruction result of the doll cat; (d) 3D reconstruction result of composite objects recovered by the method in this paper; (e) 3D reconstruction result of composite objects recovered by traditional methods; (f) The true 3D reconstruction result of the combined object

Fig. 5. 3D reconstruction results comparison of fans at different speeds. (a) Fan images collected at first speed (about 800 rpm); (b) 3D reconstruction results of fan at first speed by the traditional three-step phase shift method; (c) 3D reconstruction results of fan at first speed based on U-Net network; (d) Fan images collected at second speed (about 1800 rpm); (e) 3D reconstruction results of fan at second speed with the traditional three-step phase shift method; (f) 3D reconstruction results of fan at second speed based on U-Net network

Fig. 6. 3D reconstruction and analysis of precision sphere. (a) 3D reconstruction result of left precision sphere; (b) Error distribution of left precision sphere; (c) Error histogram of left precision sphere; (d) 3D reconstruction result of right precision sphere; (e) Error distribution of right precision sphere; (f) Error histogram of right precision sphere