Road detection in spaceborne SAR images based on ridge extraction

This paper presents an automatic and map-based road detection algorithm for spaceborne SAR images, aiming at subpixel accuracy on average. We propose a two-step algorithm which is composed of the coarse and the fine matching. In the coarse matching step, we find roughly road positions by using water areas or the generalized Hough transform. The fine matching step detects roads accurately by applying the active contour models (snake) to the novel field called the potential field. In the fine matching step, we first extract ridges or ravines of curvilinear structures in SAR images, then construct the potential field by smoothing extracted structures. The proposed method utilizes digital maps to extract information of the road model in the coarse matching and to initialize positions and shapes of snakes in the fine matching. Experimental results show the performance of detecting roads with the average error less than one pixel.