Ship Target Detection Method Based On Compact Polarimetric SAR

Compact polarimetric synthetic aperture radar(SAR)is a kind of new working mode,whose width is bigger than full polarimetric SAR,and the polarization information is richer than literal polarimetric SAR and dual polarization SAR.It is of great importance to transportation at sea and fisheries management,which become heat in recent years.In this paper,the ship target detection performance and the scattering characteristic differences of ship and sea was studied.The scattering model of ship targets in compact polarimetric SAR was built,and the new parameter of compact polarimetric SAR was put forward.Based on the new parameter,a new method of ship targets detection in compact polarimetric SAR was developed.The main job is as follows:(1)Based on the theory of compact polarimetric decomposition and the reconstructed compact polarimetric SAR data,36 compact polarimetric characteristics were got,and the scattering characteristics differences of ship and sea was analyzed comprehensively in this paper.The ships target detection performance was evaluated by using the ship and sea distance,the best six characteristics were roundness,the relative phase,circular polarization ratio,scattering angle,compact polarimetric scattering angle and the elliptical azimuth.(2)According to the above six compact polarimetric SAR characteristics,the impact of incidence angle,the window size and vessel length on the performance of ship target detection were studied,which will be a reference for the subsequent ship target detection in compact polarimetric SAR.(3)Based on compact polarimetric vector and X-Bragg scattering model,the ship target detection model was established.Taking the circular polarization ratio,relative phase and roundness for example,the scattering characteristic difference of ship and sea was analyzed.What's more,a new parameter was put forward,called phase factor.Compared with the six compact polarimetric SAR characteristics mentioned above,the advantages of phase factor was analyzed comprehensively.First,the rotation invariant characteristic of the phase factor was deduced by using compact polarimetric SAR scattering model,the value of the phase factor has nothing to do with the surface roughness,which proved the stability of the phase factor.Secondly,compared with other six compact polarimetric SAR characteristics,the ship and sea distance is 1 to 3 times of other characteristics,proved that the phase factor achieves optimal performance.(4)Based on the phase factor,a new method was developed to detect ships on the sea.The process of ship target detection method was introduced,combined with the reconstructed compact polarimetric SAR data,five test areas were selected,the result were as follows: compared with the traditional K-CFAR and G0-CFAR,the FOM of phase factor method was highest at 0.98,and FOM of K-CFAR and G0-CFAR were 0.58 and0.85,respectively.In brief,phase factor method is best,and overcome the poor automaticity problem.