SAR POLARIZATION INFORMATION FOR SHIP DETECTION

摘要

The polarization information was investigated in [8] for ship detection using calibrated polarimetric Convair-580 SAR data that were collected within the incidence angle range of 45°to 70°. It was shown that at operational satellite SAR incidence angles (lower than 60°, there is a significant improvement of ship-sea contrast when the full polarimetric information is used instead of the information provided by the (scalar) one channel polarization (HH, VV, or HV). In this paper, the investigation is extended to lower incidence angles, and the robustness of the polarimetric discriminators used for ship enhancement, is assessed at various wind conditions (7, 14 and 20 knots). Polarization channel phase information is also investigated. It is shown that the information contained in the HH-VV channel phase difference, looks to be very promizing for ship enhancement, mainly when a dual-polarized SAR is used. For optimum extraction of the polarimetric information, a general expression of the entropy is introduced, and investigated. The new entropy named "the polarization entropy" permits a significant improvement of ship-sea contrast within the operational satellite SAR incidence angles.