We develop an application to identify and characterize polygonal features in SAR images, based on a watershed algorithm, modified for a good robustness to radar noise. Our system performs a multi-scale analysis of the image. Oversegmentation is prevented by a selection of outstanding contours; regions with less prominent contours are merged This analysis is applied to Venus images from the Magellan mission. The system makes the distinction between polygonal and non-polygonal areas, and analyzes the polygon characteristics.