| Summary: | 碩士 === 國立交通大學 === 資訊科學與工程研究所 === 97 === Image registration is a fundamental problem in computer vision, and it also has been used to many research issues including stereo matching, 3D structure reconstruction, object recognition, and motion tracking. In this thesis, we focus on planar image registration. A novel image feature descriptor: spiral descriptor is proposed for image matching and correspondences refinement. The planar image registration and its optimization method is also proposed in this thesis.
The image registration system involves two major techniques, image correspondence detection/selection and homography matrix optimization. For image correspondences,
we obtain them automatically using reliable image matching methods like SIFT, but it is impossible for all cases. Therefore, we manually select pairs of corresponding points and refine using proposed spiral descriptor for the hard cases of image matching. The spiral feature points are localized in scale space and the descriptors are built along spiral-shape profile, which can achieve scaling and translation. The dynamic programming technique is used to match spiral descriptors and it is suitable for rotation invariant. For planar image registration, we propose a novel method to promote the registration accuracy. First, we estimate the homography matrix by either detecting the image correspondences automatically or selecting image corresponding points manually and refining using proposed spiral descriptor. The initial homography matrix is decomposed into its parameters and the non-linear optimization process adjusts these parameters using iterative process. Finally, the optimal homography can produce high registration accuracy for planar images.
The proposed spiral descriptor can match images automatically and robustly. For the hard cases of image matching, we select the correspondences manually and refine the positions automatically. The proposed planar image registration system not only promote the registration accuracy but also provides convenience process for user doing image registration.
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