Skipsdeteksjon i SAR data fra sivile radarsatellitter for SATHAV

Synthetic Aperture Radar (SAR) images with the capability to detect ocean-going vessels have been available since 1991. This report summarizes earlier experiences and gives and overview of new investigations of the ship detection capability using RADARSAT-1 and ENVISAT. It is shown that polarization and incidence angle are important factors for ship detection. Using co-polarization, it is recommended to use large incidence angles due to small ocean backscatter. Cross-polarized data have insignificant ocean backscatter, and the ship detection capability is depending on whether the signal from the ship is above the noise floor or not. Ships give strong enough reflections to be detected for small incidence angles using cross-polarized data. It is hard to detect small boats for large incidence angles, because the signals from small boats are below the noise floor. Ship wakes are almost impossible to detect since there is hardly any reflection from the sea.