Polarimetric radar, which can acquire full polarization information, has become mainstream in microwave remote sensing. However, radar target scattering responses are strongly orientation dependent, which makes applications such as target detection and recognition more difficult. Polarimetric roll-invariant features, which are independent of target orientations along the radar line of sight (LOS), exhibit great importance and have achieved successful applications in many fields. During the development of radar polarimetry, a number of polarimetric roll-invariant features have been found and reported. A comprehensive summary and investigation of these polarimetric roll-invariant features is necessary and valuable for current studies and further developments. This article is dedicated to this purpose and contains two main contributions. First, according to the authors’ knowledge, polarimetric roll-invariant features are thoroughly investigated. Based on their original derivation fashion, they are partitioned into six groups, including those derived from the Sinclair matrix, the Graves matrix, the polarimetric coherency and covariance matrices, eigenvalue–eigenvector-based decompositions, polarimetric coherence/correlation patterns, and the Kennaugh matrix. Meanwhile, their expressions, inner relationships, and physical interpretations are further examined and presented. Second, since ship detection is an important application for polarimetric synthetic aperture radar (PolSAR), the potential of these independent features for PolSAR ship detection is investigated and demonstrated. Experimental studies with Radar Satellite-2 ( RADARSAT-2 ) and Gaofen-3 PolSAR datasets are carried out. It is validated that the selected polarimetric roll-invariant features exhibit superior performance compared with normal polarimetric features.

中文翻译：

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偏振合成孔径雷达船舶检测的偏振滚转不变特征和应用：全面总结和研究

能够获取全偏振信息的偏振雷达已成为微波遥感的主流。然而，雷达目标散射响应强烈依赖于方向，这使得目标检测和识别等应用变得更加困难。偏振滚转不变特征与雷达视线（LOS）上的目标方向无关，具有非常重要的意义，并在许多领域取得了成功的应用。在雷达偏振测量的发展过程中，已经发现并报道了许多偏振滚动不变特征。对这些偏振滚动不变特征进行全面的总结和研究对于当前的研究和进一步的发展是必要的和有价值的。本文致力于此目的并包含两个主要贡献。首先，根据作者的知识，对偏振滚动不变特征进行了深入研究。根据它们最初的推导方式，它们被分为六组，包括辛克莱矩阵、格雷夫斯矩阵、极化相干和协方差矩阵、基于特征值-特征向量的分解、极化相干/相关模式和肯诺矩阵。 。同时，它们的表达、内在关系和物理解释也被进一步审视和呈现。其次，由于船舶检测是极化合成孔径雷达（PolSAR）的重要应用，因此研究并论证了这些独立特征在 PolSAR 船舶检测中的潜力。实验研究雷达卫星二号（ RADARSAT-2 ) 和开展了高分三号PolSAR数据集。经验证，所选的偏振滚动不变特征与普通偏振特征相比表现出优越的性能。