【摘要】 舰船检测是极化SAR系统的重要应用之一。现有的舰船检测方法容易受到旁瓣泄露的干扰，使得舰船目标的形态难以提取，导致检测结果不符合真实情况。此外，在舰船过于密集、尺度不一致的情况下，相邻舰船由于旁瓣的影响有时会被认为是单个目标，从而造成漏检。针对这些问题，该文提出一种基于极化SAR梯度和复Wishart分类器的舰船检测方法。首先，将似然比检验(LRT)梯度引入对数比值梯度框架，使其适用于极化SAR数据；基于LRT梯度图进行恒虚警(CFAR)检测，提取舰船的边缘信息，消除伪影的同时抑制强旁瓣对舰船精细轮廓提取的影响。其次，利用复Wishart迭代分类器对舰船强散射部分进行检测，可排除大部分的杂波干扰且保持舰船形态细节。最后，将二者信息融合，从而可以保持舰船形态细节的同时克服旁瓣和伪信号的虚警。该文在3幅来自ALOS-2卫星的极化SAR图像上进行了对比实验，实验表明与其他方法相比，该文所提算法具有更少的虚警和漏检，且能够有效克服旁瓣泄露，保持舰船形态细节。更多还原

【Abstract】 Ship detection is one of the most important applications of polarimetric Synthetic Aperture Radar(SAR) systems. Current ship detection methods are susceptible to side flap interference, making it difficult to extract the target shape correctly. In addition, when ships are exceedingly dense and have different scales, adjacent ships may be considered as a single target because of the influence of strong sidelobes, causing missed detections. To address the issues of sidelobe interference and multi-scale dense ship detection, a ship detection method based on the polarimetric SAR gradient and the complex Wishart classifier is proposed. First,the Likelihood Ratio Test(LRT) gradient is introduced into the log-ratio gradient framework to apply it to the polarimetric SAR data. Then, a Constant False Alarm Rate(CFAR) detector is applied to the gradient image to map the ship boundaries accurately. Second, the complex Wishart iterative classifier is used to detect the strong scattering part of the ship, which can eliminate most clutter interference and maintain the ship’s shape details. Finally, the LRT detection and complex Wishart classifier detection results are fused. Thus, not only the strong sidelobe interference can be greatly suppressed, but the dense targets with different scales are also distinguished and accurately located. This study performs comparative experiments on three polarimetric SAR images from the ALOS-2 satellite. Experimental results show that compared with the existing methods, the proposed algorithm has fewer false alarms and missed detections and can effectively overcome the problems of sidelobe interference while maintaining the shape details.更多还原