On The Theory Of Image Mosaicing And Its Related Algorithms

Image mosaicing is the art of constructing scene representation with wide view field by use of image sequences shot from real world. With great practical value, now it exerts profound influence on the research and application field of photogrammetry, virtual reality and video processing. This dissertation systematically investigated the topic and its related techniques, which are further concluded as follows:The origin, development and applications of image mosaicing are reviewed first. The fundamental theory and key techniques of image mosiacing are systemically introduced.Later, an algorithm of image mosaicing using method of block matching based on phase correlation is described, in which the motion vector field is first calculated to establish the correspondences of adjacent images, then iterative estimation on parameters of transformation model is performed to create the panoramic image. The proposed method does not need to extract features of images and takes full advantage of the image information. When the geometric deformation and the changes of the scale factor among images are not serious, the method can obtain good panoramic image.Then, an algorithm based on corner matching is put forward, which constructs the panoramic images by a sequence of operations including: the extraction of the feature points by using Harris corner detector, corner matches between image pairs with normalized cross correlation method, and the estimation of the parameters of the transformation model through Robust Random Sample Consensus (RANSAC) approach by which the outliers could be effectively eliminated.An algorithm based on optical flow field is also presented in the thesis. The algorithm builds objective function upon the parameters of transformation model according to the optical flow constraints and estimates these parameters through iterative solution. It is shown to be robust to illumination variety between images and deviations from the assumption of planar scene, or the dithering of camera.The technique of cylindrical panoramic image mosaicing is investigated. The frequency domain information of images by Fourier Transform is employed to estimate the focus of camera and the motion parameters to complete the cylinderimage mosaicing. The rotation of camera around optical axis, which resulting in mis-registering between images, is further considered during the initial estimation and refining process of motion parameters.Finally, some open issues on image mosaicing as well as the further works are pointed out.