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摘要: 目标检测与识别是高分辨合成孔径雷达(SAR)领域的热点问题。机场上飞机作为一种典型目标,其检测和识别有一定的独特性。该文回顾了SAR图像典型目标检测识别领域技术的发展过程,分析了SAR图像中飞机目标的散射机制及面临的技术难点,阐述了 SAR 飞机目标检测识别的系统流程、技术路线和关键科学问题,对基于传统与基于深度学习两个方面的飞机目标检测识别的研究进展进行了归纳总结,并讨论了各类方法的特点及存在的问题,展望了未来的发展趋势。该文认为如何将深度学习与目标电磁散射机理结合、提高网络或模型的泛化能力是提升SAR图像中目标检测识别精度的关键,并给出了一种基于散射信息与深度学习融合的飞机目标检测方法。Abstract: Target detection and recognition are popular issues in the field of high-resolution Synthetic Aperture Radar (SAR). As a typical target, aircraft detection and identification has certain uniqueness. This paper reviews the development of detection and recognition techniques for a typical target in SAR imagery, analyzes the scattering mechanism and technical difficulties of aircraft in SAR imagery, describes the system flow, technical routes, and key scientific problems of target aircraft detection and recognition in SAR imagery, summarizes the research progress from traditional methods to deep-learning-based methods for aircraft detection and recognition, discusses the characteristics and existing problems of various methods, and predicts the future development trend. This paper proposes that combining target electromagnetic scattering mechanism with deep convolutional neural network to improve the generalization capability of the model is the key to improve SAR detection and recognition performance. Moreover, this paper establishes an aircraft detection method based on the fusion of scattering information and deep convolutional neural network.
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表 1 飞机各部件散射机理
Table 1. Scattering mechanism of each component
部件 散射机理 具体描述 机头 反射/多次散射 机头是由一系列结构组成的,驾驶舱与地面成二面角结构 机身 反射/多次散射 机身包含多种纵向和横向元件:大梁、桁条、隔框和蒙皮等;发动机与机翼成二面角结构 尾翼 多次散射/边缘绕射 尾翼分垂直尾翼和水平尾翼两部分,形成二面体或三面体结构 机翼 边缘绕射 机翼包括副翼、襟翼和缝翼等结构,包含丰富的边缘信息 动力装置 腔体散射 发动机有典型的空腔结构 表 2 机场检测算法效果论证
Table 2. Demonstration of airport detection algorithm effectiveness
算法 正确检测目标数目(个) 漏检目标数目(个) 虚警目标数目(个) 虚警率(%) 精确率(%) 未进行机场检测 580 28 103 15.1 84.9 进行机场检测 580 28 50 7.9 92.1 表 3 基于GF-3与TerraSAR-X卫星数据的散射信息增强效果对比
Table 3. Results of algorithm without/with scattering information enhancement based on GF-3 and TerraSAR-X data
算法 检测结果 GF-3 TerraSAR-X 合计 未进行散射信息增强特征金字塔算法 正检个数 429 133 562 漏检个数 42 4 46 虚警个数 53 14 67 虚警率(%) 11.0 9.5 10.7 召回率(%) 91.1 97.1 92.4 精确率(%) 89.0 90.5 89.3 散射信息增强特征金字塔算法 正检个数 445 135 580 漏检个数 26 2 28 虚警个数 43 7 50 虚警率(%) 8.8 4.9 7.9 召回率(%) 94.5 98.5 95.4 精确率(%) 91.2 95.1 92.1 表 4 SAR图像飞机目标检测识别算法对比
Table 4. Comparison of different aircraft detection and recognition methods in SAR imagery
算法 具体分类 具有的优势 存在的问题 传统的方法 基于目标结构特征 算法的稳定性较好 需要先验信息,难以推广应用 基于目标散射特征 目标几何特征 算法的速度较快 容易受背景杂波干扰 灰度统计特征 算法的稳定性较好 建立统一的目标统计模型难度大 目标纹理特征 算法精度较高 鲁棒的目标局部纹理特征提取难度大 基于深度学习的方法 直接应用深度学习 算法的精度较高,算法速度较快 训练样本需求量大,网络泛化能力差 结合目标散射特征 算法的精度较高,稳定性较好 训练样本需求量大,训练过程较为复杂 -
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