Dual-frequency structured light coding and decoding method for real-time three-dimension reconstruction

In order to realize real-time three-dimensional (3D) reconstruction, this paper proposes a novel dual-frequency method for measuring the 3D surface geometry of objects. First, a group of unit-frequency sinusoidal wave patterns and a group of high-frequency sinusoidal wave patterns are combines. Then the generated patterns are projected onto the object surface and the reflected patterns distorted by the object are captured by a camera simultaneously. Second, the unit-frequency phase and high-frequency phase can be derived through the captured unit-frequency patterns and high-frequency patterns respectively. The unwrapped phase can be obtained by unwrapping the high-frequency phase by means of the unit-frequency phase which represents the correspondences between the projector and the camera, i.e., the high-frequency patterns guarantee high-quality phase and the unit-frequency patterns help to conveniently unwrap the wrapped phase generated from the high-frequency patterns. Finally, the high-quality 3D point clouds of the object can be computed using the unwrapped phase through triangulation. To confirm the validity of the proposed method, a statue is scanned and the results indicate that the variance of the phase error is 5.5591×10 rad and the sweep time is 0.1563 s. Compared with the data of the traditional methods, the proposed method reduces the number of projected patterns and keeps the accuracy of reconstructed results.