Demonstration of Super-Resolution for Tomographic SAR Imaging in Urban Environment
Demonstration of Super-Resolution for Tomographic SAR Imaging in Urban Environment
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DOI：
10.1109/tgrs.2011.2177843
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发表时间：
2012-08
影响因子：
8.2
通讯作者：
Xiaoxiang Zhu;R. Bamler
中科院分区：
文献类型：
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作者：
Xiaoxiang Zhu;R. Bamler
层析合成孔径雷达（SAR）反演，包括SAR层析成像和差分SAR层析成像，本质上是一个光谱分析问题。仰角方向的分辨率取决于仰角孔径大小，即轨道的扩展。由于现代米分辨率星载SAR系统（如TerraSAR-X）的轨道受到严格控制，层析高程分辨率至少比距离和方位角分辨率低一个数量级。因此，需要超分辨率（SR）重建算法。考虑到高程信号的稀疏性，作者在之前的论文中提出了一种基于压缩感知的超分辨算法，名为“L1范数最小化，模型选择和估计重建”（SL1MMER，发音为“slimmer”）。研究了该技术在定位精度和SR功率上的极限。本文通过几何分析和统计分析，说明了SR在城市基础设施监测中的重要作用。结果表明，小海拔距离的双散射体比大海拔距离的双散射体出现频率高。此外，使用TerraSAR-X真实数据示例验证了SL1MMER的SR能力。对于高层建筑群，检测到的双散射体的百分比几乎是传统线性估计的两倍。其中，探测到的双散射体对中，有一半的高程距离小于瑞利高程分辨率。这证实了SR对于这类应用程序的重要性。
Tomographic synthetic aperture radar (SAR) inversion, including SAR tomography and differential SAR tomography, is essentially a spectral analysis problem. The resolution in the elevation direction depends on the elevation aperture size, i.e., on the spread of orbit tracks. Since the orbits of modern meter-resolution spaceborne SAR systems, such as TerraSAR-X, are tightly controlled, the tomographic elevation resolution is at least an order of magnitude lower than in range and azimuth. Hence, super-resolution (SR) reconstruction algorithms are desired. Considering the sparsity of the signal in elevation, a compressive sensing based super-resolving algorithm, named “Scale-down by L1 norm Minimization, Model selection, and Estimation Reconstruction” (SL1MMER, pronounced “slimmer”), was proposed by the authors in a previous paper. The ultimate bounds of the technique on localization accuracy and SR power were investigated. In this paper, the essential role of SR for layover separation in urban infrastructure monitoring is indicated by geometric and statistical analysis. It is shown that double scatterers with small elevation distances are more frequent than those with large elevation distances. Furthermore, the SR capability of SL1MMER is demonstrated using TerraSAR-X real data examples. For a high rise building complex, the percentage of detected double scatterers is almost doubled compared to classical linear estimators. Among them, half of the detected double scatterer pairs have elevation distances smaller than the Rayleigh elevation resolution. This confirms the importance of SR for this type of applications.