The number of patterns used to reconstruct one 3D image is of great importance to high-speed 3D shape measurement. This paper presents a method to reduce the number of patterns by using Hilbert transform with only three binary patterns. Two fringe patterns at different frequencies and one DC component pattern are used for absolute phase retrieval. We directly applied Hilbert transform to the difference maps generated by subtracting the DC component from the fringe patterns. Then, with two-frequency phase unwrapping method using geometric constraints, the absolute phase is retrieved robustly. We designed a system to capture 2D images at 6,000 Hz, and achieved 3D geometries at 2,000 Hz. Experimental results verified the success of the proposed method.
|