Imaging Technologies to the Inner Surface of an Opaque Paper Cup
| Autor: | Yang Shin-Yi, 楊詩億 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 This paper applies a fisheye camera in capturing image of the inner surface of a paper cup for developing automatic inspecting application. The creative motivation bases on the inherent optic property of the fisheye lens. It focuses images well to objects immersed in the semi-spherical space viewing as well as it scales image evenly to picture inside a sphere shell, which takes space angle as a reference unit. To a typical cup inspection setup, the body is bounded inside a virtual semi-sphere and its inner surface is near a spherical shell. So, a fisheye camera can image the inner surface of paper cup well. If a common camera is used in cup inspection, the imaging mapping is as taking central perspective transformation from a hollow body to a plane. Under a properly configuration, morphologically, its bottom figures perform exactly constant amplification. However, the part on the side-wall wall would progressively deform and blur. This distortion is progressively worse from bottom upward. Therefore, a directly front exposure cannot present a reasonable image inside the cup for machine vision application. Regarding image construction scheme of a paper cup, fisheye lens owns many good properties. It is a center based radial mapping from a cylindrical body to a semi-sphere shell. While the shape is totally distorted, the image deformation can evenly distributed to every part of the internal surface. Moreover, the intensity difference in the sidewall will not too heavy to a practical application. Under a deliberate setup, the signature can keep similar image quality throughout the inside of the inspected cup. Experimental set-up was designed and implemented to survey the optic properties of the imaging inside the paper cup. The achievements were reviewed and discussed in this paper. It is concluded that fisheye camera perform well as our forecast. Other than typical components of the camera, the lens, the computer, and software, a home-made light source apparatus was purposely developed. However, with all our effort, the intensity difference between sidewall zone and bottom zone cannot reach that of a common machine vision application. If it is accepted, many well-developed algorithms cannot directly adapt to process fisheye image. For a deeper study, at the final part of this paper the FRED optic software package is used to numeric analysis the home-made light source. While some achievement in tuning intensity error is also presented, the further study is needed. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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