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摘要: 传统合成孔径雷达(SAR)成像可视为点目标散射模型约束下数据空间到图像空间的映射。然而,真实目标多为延展目标,与传统线性成像处理中的点目标散射模型存在失配,会导致SAR图像表征失真。常见的现象是使延展目标多呈现为孤立强点,阻碍了基于SAR图像的目标辨识等应用。SAR参数化成像技术是为解决上述模型失配问题而诞生的一种非线性成像方法,特点是兼顾点目标和延展目标的散射模型。具体来说,是通过利用不同类别目标的回波或图像的相位与幅度特征对观测角度的敏感性,辨识目标类型,反演目标散射参数,进而根据目标散射的参数化模型,重建目标图像的技术。在对延展目标成像时,可获得比传统线性成像方法更好的图像质量。该文主要介绍了线型延展目标的参数化成像技术,对应真实场景中的孤立强点和连续边缘,深入讨论了基于回波域、图像域的参数化成像技术和试验结果,展望了未来SAR参数化成像技术的发展趋势。Abstract: Under the constraints of the point scattering model, traditional Synthetic Aperture Radar (SAR) imaging algorithms can be regarded as a mapping from data space to image space. However, most objects in the real scene are extended targets, which are mismatched with the point scattering model in traditional linear imaging algorithms. The abovementioned reasons lead to the distortion of SAR image representation. A common phenomenon is that the extended targets appear as isolated scattered points, which hinder the application of target recognition on the basis of SAR images. SAR parametric nonlinear imaging techniques are established to solve the abovementioned model mismatch problem. Such methods are characterized by the scattering models that consider point targets and extended targets. Specifically, by using the sensitivity of the phase and amplitude characteristics of the echoes or images to the observation angles, SAR parametric imaging methods can first identify the target type and estimate the scattering parameters, and then reconstruct the target image on the basis of the scattering model. SAR parametric imaging methods can obtain better image quality than traditional linear methods for extended targets. This article mainly introduces the parametric imaging methods of linear extended targets, which correspond to the isolated strong points and continuous edges of objects in the real scene, and discusses the parametric imaging methods on the basis of the echo and image domains and experimental results. Last, the future development trends of SAR parametric imaging methods are discussed.
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Key words:
- Synthetic Aperture Radar (SAR) /
- Parametric imaging /
- Extended targets
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表 1 不同成像方法效果对比分析
Table 1. Analysis of the effects of different imaging methods
类型 成像方法 优点 缺点 线性方法 圆迹SAR BP成像 1.成像分辨率高
2.目标展现度高1.算法计算量大
2.实时性差
3.对雷达航迹需求高
4.数据量大非线性方法 压缩感知SAR成像 1.成像分辨率高
2.成像质量高
3.数据量小1.低信噪比下易出现虚假目标
2.算法计算量大
3.目标特征直观可视效果低多角度SAR图像融合 目标展现度高 1.数据量大
2.图像需要配准回波域参数化成像 1.目标展现度高
2.数据量小
3.成像质量高1.需要至少两个观测角度数据
2.处理多目标困难图像域参数化成像 1.目标展现度高
2.数据量小
3.成像质量高1.需要至少两个观测角度数据
2.图像需要配准 -
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