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与单极化SAR(Synthetic Aperture Radar)相比,全极化SAR图像中不仅包含散射目标的几何特征和后向散射特征,还包含散射目标的极化特征。因此,基于极化特征的SAR图像分类能够更全面地描述海面目标的物理特性。单次反射特征值相对差异度(Single Bounce Eigenvalue Relative Difference,SERD)能够比较单次散射机制的相对大小,并且可以反映散射表面的粗糙度情况。而海面油膜的存在抑制了海面的短重力波和毛细波,改变了海表面的粗糙度。基于此,本文将SERD应用到海面溢油检测中。利用两景Radarsat-2全极化SAR数据对比分析了SERD与极化散射熵的溢油检测效果,实验发现:(1)SERD能够较好地区分溢油与海水。(2)对原油而言,SERD的油水对比度与极化散射熵的油水对比度在数值上差异较小;对生物油膜而言,SERD的油水对比度在数值上远小于极化散射熵。利用这一特性,SERD在区分生物油膜与原油方面更具优势。
Compared with the Synthetic Aperture Radar, the fully polarimetric SAR image contains not only the geometric features and the backscattering features of the scattering target, but also the polarization characteristics of the scattering target. Therefore, the classification of SAR images based on polarization features can describe the physical characteristics of sea targets more fully. The Single Bounce Eigenvalue Relative Difference (SERD) can compare the relative sizes of the single scattering mechanisms and reflect the roughness of the scattering surface. However, the existence of oil film in the sea suppresses the short gravimetric waves and capillary waves on the sea surface and changes the roughness of the sea surface. Based on this, this paper will SERD applied to the sea oil spill detection. Based on the data of Radarsat-2 and Polarimetric polarimetric SAR, the results of oil spill detection using SERD and Polarimetric scattering entropy were compared. The results show that: (1) SERD can distinguish oil from seawater well. (2) For crude oil, the oil-water contrast of SERD is slightly different from the oil-water contrast of polarization scattering entropy. For oil film, the oil-water contrast of SERD is far less than that of polarization scattering entropy. With this feature, SERD has the advantage of differentiating between bio-film and crude oil.