A visual circle based image registration algorithm for optical and SAR imagery

A visual circle based image registration algorithm for optical and SAR imagery is proposed in this paper. The visual circles with robustness to angle differences and flexible resolution build a bridge between the reference and sensed images with different resolutions and angles, and combine the spatial features and correlation measures together for the feature matching. Two universal correlation measures comprising normalized cross correlation coefficient (NCCC) and normalized mutual information (NMI) are adopted respectively for registration between Radarsat-2 and ASTER images. In order to testify the visual circle´s robustness to rotation, the visual squares and circles were constructed meanwhile and used to register the rotated sensed images with different angles respectively. The results proved that the total RMS error of the proposed algorithm was less than one pixel and the circle had higher robustness to angle differences and better performance than that of the square.