Ship detection with polarimetric synthetic aperture radar (PolSAR) images has attracted a lot of attention in recent years. However, modeling the distribution of clutter is a complicated task. This article introduces a distribution independent ship detector for PolSAR images. First, in order to improve the detection performance, the multichannel PolSAR data are projected onto a 1-D space utilizing an adaptive linear filter. The design of linear filter is modeled as a nonconvex optimization problem with the principle of maximization target-to-clutter ratio, which is solved by an iteration optimization algorithm. Then, the convergence and computational complexities of the proposed algorithm are theoretically analyzed. After that, a distribution independent detector with a bounded constant false alarm rate property is proposed to distinguish ships from sea clutter. The detection threshold is calculated based on the Markov inequality without modeling the statistical distribution of clutter. Experiments are carried out on real Radarsat-2 and AirSAR data to test the proposed detector. The results demonstrate that the proposed detector, which takes the distribution independent and unsupervised properties as the main advantages, also achieves comparable detection performance with state-of-the-art methods. Moreover, additional experiments verify the robustness of the proposed detector to the initialization of the algorithm, even though the optimization problem is nonconvex. Finally, the effects on detection results caused by polarization characteristics are investigated to give a further explanation about linear polarization enhancement.

中文翻译：

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一种用于 PolSAR 图像的分布独立的船舶探测器


近年来，利用极化合成孔径雷达（PolSAR）图像进行船舶检测引起了广泛关注。然而，对杂波分布进行建模是一项复杂的任务。本文介绍了一种独立于分布的 PolSAR 图像船舶探测器。首先，为了提高检测性能，利用自适应线性滤波器将多通道 PolSAR 数据投影到一维空间。线性滤波器的设计被建模为一个非凸优化问题，其原则是最大化目标杂波比，并通过迭代优化算法来求解。然后，从理论上分析了该算法的收敛性和计算复杂度。之后，提出了一种具有有界恒定误报率特性的分布独立检测器来区分船舶和海杂波。检测阈值是基于马尔可夫不等式计算的，没有对杂波的统计分布进行建模。在真实的 Radarsat-2 和 AirSAR 数据上进行了实验，以测试所提出的探测器。结果表明，所提出的检测器以分布独立和无监督特性为主要优点，也实现了与最先进的方法相当的检测性能。此外，额外的实验验证了所提出的检测器对算法初始化的鲁棒性，即使优化问题是非凸的。最后，研究了偏振特性对检测结果的影响，进一步解释了线性偏振增强。