Polarimetric SAR ship detection based on superpixel and sparse reconstruction saliency
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摘要: 极化SAR舰船检测是极化SAR系统的重要应用之一,现有的极化SAR舰船检测方法在具有强背景杂波的条件下容易将强杂波误检为目标,造成虚警;在多尺度舰船检测情况下小尺寸的舰船容易淹没在背景杂波中,造成小尺寸目标的漏检。针对上述问题,本文提出一种基于超像素与稀疏重构显著性的极化SAR舰船检测方法。该方法首先用超像素分割方法将大幅的极化SAR场景图像分割,在超像素级别上使用稀疏重构显著性方法保留含有舰船目标的超像素,再在这些保留下来的超像素中逐像素使用稀疏重构显著性检测方法,得到最终的舰船检测结果。本文选取强杂波场景和多尺度舰船检测场景的两个场景的ALOS-2卫星极化SAR数据进行对比实验,实验结果表明,本文方法在强杂波场景下品质因数达到94.87%,在多尺度舰船检测场景下品质因数达到94.05%。Abstract: Polarimetric SAR ship detection is an important application of the polarimetric SAR system. Existing polarimetric SAR ship detection methods are plagued by erroneous detection of strong clutter and missed detection of small targets in multiscale situations. Particularly, the existing methods easily detect strong clutter as the target under strong background clutter, resulting in false alarms; in the case of multiscale ship detection, small ships are easily submerged in background clutter, resulting in missed detection of small targets. To solve these problems, this paper proposes a polarimetric SAR ship detection method based on superpixels and sparse reconstruction saliency. This method has two stages. In the first stage, the large polarimetric SAR ship detection scene image is segmented using the superpixel segmentation method to obtain a superpixel image. With the superpixel as the basic unit, a saliency detection method based on sparse reconstruction is used to obtain the saliency value of each superpixel in the image. Then, the superpixels that may contain ship targets are retained using the sea surface ship density defined in this paper. Accordingly, in the first stage, the superpixel regions that may contain ship targets are obtained through superpixel segmentation and sparse reconstruction saliency detection. Next, in the second stage, a saliency detection method based on sparse reconstruction is used to obtain the saliency value of each pixel in these reserved superpixel regions. Finally, the global threshold segmentation method is used for the pixels in these regions to obtain the final detection results of ship targets. In this paper, two polarimetric SAR images of the ALOS-2 satellite with different scenes were selected for an experiment. One image contains strong clutter on the sea surface; the other contains ships of different sizes and many small ships. The experimental results show that the proposed method can well determine the superpixel regions that may contain ship targets in the first stage and successfully obtain the ship detection results in the second stage. In addition, in both scenarios, the classic constant false alarm rate (CFAR) methods and a saliency detection method are used for comparison with the proposed method. The experimental results show that the proposed method produces almost no false alarms because it is insensitive to strong clutter; moreover, this method rarely misses small ship targets in the multiscale ship detection scene. The figure of merit of the proposed method reaches 94.87% in the strong clutter scene and 94.05% in the multiscale ship detection scene.
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Key words:
- polarimetric SAR /
- ship detection /
- sparse reconstruction /
- superpixel segmentation /
- saliency detection
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表 1 场景一极化SAR舰船定量检测结果
Table 1. Polarization SAR ship quantitative detection results of scene 1
Method Nc NFA NM FoM/% CA-CFAR 37 3 2 88.10 OS-CFAR 36 5 3 81.82 Saliency method 35 0 4 89.74 Our method 37 0 2 94.87 表 2 场景二极化SAR舰船定量检测结果
Table 2. Polarization SAR ship quantitative detection results of scene 2
Method Nc NFA NM FoM/% CA-CFAR 75 0 7 91.46 OS-CFAR 77 6 5 87.50 Saliency method 65 0 17 79.27 Our method 79 2 3 94.05 -
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