Study Of 3D Reconstruction Based On Structured Light Projection Technology

Three-dimensional reconstruction technology has a very wide range of applications in the medical, aviation, robot navigation, three-dimensional measurement, virtual reality and other professional areas. The study of this technology is useful for shortening the development cycle and greatly improving the efficiency of product design. Currently, there are many techniques to reconstruct the three-dimensional structure of an object, but some of these methods must rely on expensive equipments or need to spend a lot of computation time, which results in relatively low efficiency. Herewith the issue to be solved is that how to not only maintain a relatively high efficiency (less time-consuming ) but also has a lower cost (less equipment needs), and to enable users to choose appropriate reconstruction schemes according to their specific needs of different applications. Study of such a three-dimensional reconstruction system is of great significance, which is just the starting point of this research project.A projector-camera (ProCam) system was set up in this research. The camera and projector were firstly calibrated separately, then the triangulation theory and binocular vision principle were used for the three-dimensional reconstruction based on the structured light projection technique. As the core technology of three-dimensional reconstruction, different coding strategies of structured light were discussed, classified and compared with one another. Then two main coding strategies were implemented, of which the Gray Code + Phase Shifting coding strategy can be used to reconstruct complex objects with the advantages of simple encoding and decoding, but it costs rather long time. Another coding strategy is based on De Bruija sequence, which only needs to project coding image once so the consumption time is only one-twentieth of the previous one, but its encoding and decoding process are quite complex, and this strategy cannot reconstruct objects with complex structure or rich colors. The experiments were carried out to analyze and compare these two coding strategies in detail, on the basis of which their different suitable applications were pointed out. Both strategies have been successfully achieved in the reconstruction system of this research, so that the users could select the applicable coding strategies scientifically and practically for their required three-dimensional reconstructions.As the application examples of the achievements in this research, a non-planar projection correction method was proposed based on the three-dimensional reconstruction technology of this system. The experimental results of correction on a curved surface indicated that the images captured by a camera as the observer were no longer distorted by the impact of the surface and achieved the similar display effects as the original images. In addition, a projector-moving detection technique was put forward. When the projector is moved in practical projection display process, it is not necessary to recalibrate the device, and the new projection calibration parameters will be computed automatically by this system. The errors of the new calibration parameters were evaluated, by the projector-moving experiments, as being less than 1% , which implied that the restored display effects were very close to those before the projector was moved.Finally, the main work of this dissertation was summarized, and the perspective of the future study was also forecasted.