Study On Calibration Of Three - Dimensional Morphology And Deformation Measurement System For Structural Light

Structural instability caused by material deformation commonly accompany some accidents, in which rock mass and rock deformation can lead to earthquakes, landslides, earth surface subsidence occurred and other geological disasters. The occurrence of disasters leads to tremendous disaster and loss, thus the importance of deformation measurement arouse growing attention. The three-dimensional shape measurement can not only reflect nature of the object which can indirectly measure deformation and also can directly measure deformation. In this case, the structured light3D shape and deformation measurement system emerges. The system’s accuracy depends largely on the accuracy of the calibration system. So the in-depth study of calibration method is very necessary.In this thesis, it does comparative analysis and research on varieties of visual models which have been proposed by the previous scholars. On this basis, it builds the mixed distortion visual model that can describe the various aberrations cameras and projectors accurately. The precise mathematical model lays a theoretical foundation for the precision calibration results. It is innovative to apply the mixed distortion visual model in the projector calibration, which has rarely been reported.In order to achieve automatic calibration for the system, this thesis has summarized the some classical calibration object in traditional camera calibration, and a two-dimensional planar calibration board has been designed through the comparative analysis and on the basis of meeting the demand of camera automation calibration. After the center coordinates of circle targets has extracted using a sub-pixel ellipse fitting method, an algorithm for automatic numbering all circular targets has proposed. The experimental results show that the algorithm is practical, with strong robustness and good stability. Comprehensive considering Zhang’s calibration algorithm and the visual model adopted in this thesis, the selection of initial value in the algorithm as well as the optimization process has been improved, and complete the camera calibration. Calibration results show that the calibration template designed, the automatic numbering algorithm and the improved calibration algorithm are very effective, the calibration algorithm has high flexibility, high calibration precision and good stability. The projector is regarded as a reverse camera, in order to get high precision projector calibration results, using projector DMD image generation method and obtain the information of feature points, and the camera calibration approach is used to calibrate the projector. Calibration results show that this method is reasonable and hybrid distortion model can improve the calibration accuracy. The solution to obtain the location relationship between the camera and projection is analyzed and the solution formula is deduced. Finally, in order to achieve maximum automatic calibration, the structured light3D shape and deformation measurement system calibration software has designed and developed. Then the thesis elaborates the design of the main functional modules and mutual relationship of them and presents the interface software.