Three-Dimensional Complex Shape Measurement Using Heterodyne Principle with Binocular Stereo Vision

Three-dimensional (3-D) shape measurement for an object has been a hot topic in recent years due to its wide field of application. In order to implement the 3D shape measurement for complex shape object, a measurement framework based on heterodyne principle is proposed in this work. Firstly, the four-step-phase-shifting algorithm is adopted to generate twelve different fringe patterns with three different frequency, meanwhile, the relative phase can be obtained. Then, the phase unwrapping using the heterodyne process is carried out to compute the beats using relative phase. Finally, the absolute phase images are operated by binocular stereo correspondence method, and the 3D points can be obtained by the classic triangulation method. To verify the proposed measurement framework, a 3D measurement hardware system is developed, which consists of DLP Lightcrafter 4500 and two Basler cameras. Experimental results for two different statue objects confirmed that the proposed framework could be applied to arbitrary 3D shape measurement, even for the complex shape.