I. Introduction
Ship surveillance has gained great attention in recent years owing to the increasing maritime concerns, e.g., on piracy and illegal fishing. In particular, ship detection via synthetic aperture radar (SAR) has become a popular choice, due its many advantages including the all-time/all-weather operational capability, high resolution, wide coverage, etc. Applications have been reported using TerraSAR-X [1], RADARSAT-2 [2], and ALOS-PALSAR [3].