Automatic Aerial Image RegistrationWithout Correspondence

This paper presents an approach for registering aerial images taken at different time, viewpoints, or heights. Different from conventional image registration algorithms, our approach does not need image matching or correspondence. In this approach, we extract a number of corner features as the basis for registration and create a number of image patches with the corner points as centers on both reference and observed images. In order to let the corresponding patches cover same scene, we use a circle which the radius can be changed as the shape of the image patches. In this way, the image patches can handle the case in which there are rotation and scaling at the same time between reference and observed images. With the orientation differences of patches between these two images, we create an angle histogram with a voting procedure. The rotation angle between the two images can be determined by seeking the orientation difference that corresponds to the maximum peak in the histogram. Once we get the rotation angle, we seek back for the two corresponding patches which the value of orientation difference is the same as the rotation angle. The ratio of radii of these two patches is the value of the scaling. The proposed approach can handle the situation of large rotation and scaling between reference and observed images. It is applied to real aerial images and the results are very satisfying.