Detecting small ships in TerraSAR-X/TanDEM-X acquisitions at large grazing angle and moderate metocean conditions

Inhalt:
The feasibility of detection of small ships in open sea using space-borne Synthetic Aperture Radar (SAR) techniques has been a hot research topic in the latest years. The increasing interest is justified by the large availability of Very High Resolution (VHR) civil SAR satellite missions, such as TerraSAR-X/TanDEM-X, COSMO-SkyMed and RADARSAT-2. In parallel, much attention has been paid to predict the minimum detectable ship size depending on the radar settings, e.g. resolution, transmitting and receiving polarization, radar angle of incidence, and metocean conditions, e.g. sea surface wind speed, sea surface wave height. Both, the simulated ship detectability model and data-driven approach show that at large radar grazing angle and starting with moderate metocean conditions, the probability of detecting small ships in single polarization (HH or VV) SAR data is drastically reduced. This paper investigates the potential of the coherent dual polarimetric phase information and additional polarimetric features in detecting small ships in this challenging environment. The goals are achieved with the help of dual co-pol (HH and VV) TerraSAR-X/TanDEM-X data acquired in the Mediterranean Sea in the framework of a large data collection campaign, where ships ground truth information is given by self-reporting messaging system.