Robust Optical-to-SAR Image Matching Based on Shape Properties

Although image matching techniques have been developed in the last decades, automatic optical-to-synthetic aperture radar (SAR) image matching is still a challenging task due to significant nonlinear intensity differences between such images. This letter addresses this problem by proposing a novel similarity metric for image matching using shape properties. A shape descriptor named dense local self-similarity (DLSS) is first developed based on self-similarities within images. Then a similarity metric (named DLSC) is defined using the normalized cross correlation (NCC) of the DLSS descriptors, followed by a template matching strategy to detect correspondences between images. DLSC is robust against significant nonlinear intensity differences because it captures the shape similarity between images, which is independent of intensity patterns. DLSC has been evaluated with four pairs of optical and SAR images. Experimental results demonstrate its advantage over the state-of-the-art similarity metrics (such as NCC and mutual information), and show the superior matching performance.