On the use of polarimetric SAR data for ship detection

The polarization information is investigated for ship detection, using the polarimetric Convair-580 SAR. Ocean and ship polarimetric signatures are analysed within the incidence angle range 45°-70° using a data set off the Nova Scotia coast. It is shown that among the classical linear polarizations HH, VV, and HV, the polarization HH gives the best ship-sea contrast at grazing angles, even though the sea clutter is the lowest for the HV polarization. Circular polarizations perform better than the HH polarization at lower incidence angles. The polarization entropy is investigated for use in ship detection. It permits a significant improvement of the ship-sea contrast for incidence angles up to 60°. For larger incidence angles, the increasing heterogeneity of the ocean scattering mechanisms reduces the efficiency of the polarization entropy tool for ship discrimination