【摘要】 受到海面整体运动、海面后向散射系数相对低以及海况的影响,海洋锋特征在SAR图像中表现较弱,给后续的应用带来困难,亟需开展海洋锋特征增强方法的研究。SAR海面回波可以分解成Bragg散射分量和非极化分量,本文提出了一种基于非极化分量的SAR图像海洋锋特征增强方法。首先对双极化(VV和HH极化)数据进行辐射定标,为解决非极化分量提取过程中噪声增强的问题,对定标结果进行滤波;然后计算Bragg散射极化比;最后借助于极化差和极化比提取非极化分量,实现海洋锋特征增强。本文使用ALOS PALSAR数据进行处理验证,并通过计算峰值-背景比(PBR)和等效视数(ENL)进行定量分析。实验结果表明,经过本文方法处理后PBR较双极化图像可以提升15%以上,ENL较双极化图像可以提升30%以上。实验结果证明了方法的有效性,为后续的应用奠定基础。更多还原

【Abstract】 Owing to the sea surface motion,relatively low NRCS of the sea surface,and influence of the sea state,the oceanic front features in SAR images tend to be weak;this causes difficulties in subsequent applications.Therefore,it is imperative to develop methods for enhancing oceanic front features.The sea surface echoes received by SAR can be decomposed into Bragg scattering components and nonpolarized components.This paper proposes a method for enhancing oceanic front features based on these nonpolarized components.First,dual co-polarization(VV and HH)radar data are calibrated.To address the problem of noise enhancement during the extraction of nonpolarized components,the calibrated results are filtered.Subsequently,we calculate the Bragg model polarization ratio.Finally,the nonpolarized components are extracted based on the polarization difference and polarization ratio to enhance the oceanic front features.In this study,the ALOS PALSAR data are processed.Quantitative analyses are performed by calculating the peak-to-background ratio(PBR)and the equivalent number of looks(ENL).The experimental results indicate that the PBR increased by more than 15% and the ENL increased by more than30%,as compared with those for dual-polarization images.These experimental results prove the effectiveness of the proposed method,serving as the basis for subsequent applications.更多还原