| 3-D shape measurement and graphics model reconstruction is a branch of computer image processing and also a research direction that integrates machine vision and computer image and graph processing. It has a wide and urging application in the fields of Automation Process, Machine Vision, CAD, Virtual Reality (VR), Medicine and so on. This paper presents a method, Grating Projection, that captures the 3-D surface profilometry of an object at a high speed but noncontact. It is a whole-field measurement technology. Because of the cragginess of the 3-D surface, the distortion stripes appear when the common rectangular grating or sine grating is projected onto the object surface, which includes information about the 3-D surface profilometry. The images containing distortion stripes are taken by CCD camera. The 2-D stripes information is obtained by processing these images. On the basis of mathematic reconstruction model and algorithms, the 3-D surface profilometry data are finally got.The paper consists of the system design, digital image processing, and the research on mathematic reconstruction model and algorithms. The thinning algorithms and subpixel measurement techniques are discussed in Chapter 2. Describing and comparing several typical thinning algorithms, appropriate improvements are made to one of them. Then, gray moments, a method making edge location to subpixel values, is used to improve the precision of the point clouds. Furthermore, Chapter 3 presents the theory of phase measurement in grating projection and the result of the phase shifting measurement. The stripe images containing phase information are taken when several phase shifting gratings are projected onto the object surface according to phase shifting measurement requirements. After analyzing these images to get the phase about the 3-D surface profilometry, the 3-D surface data are got based on the phase-height conversion algorithm. Finally, we point out the deficiency of our system and the further jobs. |
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