3D Measurement Based On Binocular Structured Light System

Let the machine has a vision like human beings, has been a dream pursued by generations, and machine vision is happened to the discipline of this field Among numerous methods of machine vision, three-dimensional imaging techniques have been becoming more and more popular, thanks to the development and progress made in the fields of computing technology, microelectronics, optics and so on. Even though, there are still quite amount of rooms for improvement.In all the different varieties of3D imaging technologies, binocular vision and structured light are two of those attracted wide interest. The principle of binocular vision is relatively simple, it has low background environmental requirements, and it’s the closest way to the biological visual system, all these made binocular vision a hot topic of research all over the world. However, this method has the difficult to obtain depth information without the texture, and the matching calculation is generally large. Phase shift represented structured light system has high accuracy, but the calibration and non-linear effect correction of the projector is very time-consuming.In this paper, binocular vision is studied at the first, then digital fringe information is added to the scene by an extra projector, after that binocular structured light system is established. In contrast to binocular vision alone, binocular structured light system improve the accuracy of the measuring system, and stereo matching become more easily to operate because of the phase from two directions, which reduce the stereo matching cost. As to compare with traditional structured light technology, the nonlinear error about the projector is the same in left and right image, this means the time-consuming calibration of the projector can be passed. Concentrated in binocular structured light system, the two following aspects had been studied in this paper:1. Research on stereo calibration, and developed a tool kit for fast image acquisition and stereo calibration.2. Research on binocular vision systems. A binocular vision system is installed with two high-precision lenses and two progressive CMOS cameras. In the system, the synchronization of the left and right camera had been accomplished, three stereo match algorithms, namely BM, SGBM and GC, had been integrated and the measurement result of this system is also given in the paper.3. Research on binocular structured vision systems on the basis of binocular vision. In the acquisition procedure of the two phase maps, an dual-frequency pattern scheme is adopted, which use a LUT to not only calculate the wrapped phase, but also retrieve the absolute phase. Compared to the traditional phase shift technology, the new method avoiding the large computing costs of arctangent calculation and the ambiguity in phase unwrapping.Stereo match based on phase is implemented after the retrieving of absolute phase maps. After stereo match, the3D information can be get by the triangulation. The measurement result with error analysis of this system is also given in the paper.