With the launch of several planetary missions in the last decade, a large amount of planetary images has been already acquired and much more will be available for analysis in the coming years. The image data need to be analyzed, preferably by automatic processing techniques because of the huge amount of data. Although many automatic feature extraction methods have been proposed and utilized for earth remote sensing images, these methods are not always applicable to planetary data that often present low contrast and uneven illumination characteristics. Here, we propose a new unsupervised method for the extraction of different features of elliptical and geometrically compact shapes, such as craters and rocks of compact shape (e.g., boulders), to be used for image registration purposes. This approach is based on the combination of several image processing techniques, including watershed segmentation and the generalized Hough transform. The method potentially has application for extraction of craters, rocks, and other geological features.