Double-Bounce Component in Cross-Polarimetric SAR From a New Scattering Target Decomposition
Double-Bounce Component in Cross-Polarimetric SAR From a New Scattering Target Decomposition
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DOI：
10.1109/tgrs.2013.2268853
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发表时间：
2013-08
影响因子：
8.2
通讯作者：
Sang‐Hoon Hong;S. Wdowinski
中科院分区：
文献类型：
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作者：
Sang‐Hoon Hong;S. Wdowinski
通常的植被散射理论假定合成孔径雷达(SAR)交叉极化(cross-polal)信号仅代表体散射。我们发现，基于在南佛罗里达大沼泽地获取的SAR相位测量，这一假设是不正确的，这表明交叉极化雷达信号经常对植被下的水面进行采样。基于这些新的观测结果，我们提出交叉极信号由双反跳分量和体散射分量组成。产生交叉极信号的最简单的多反弹散射机制发生在旋转的二面体上。因此，我们利用旋转二面体机制对一些植被散射理论进行了修正，提出了一种包含单反、共极双反、交叉极双反、体散射分量的四分量分解算法。我们使用RADARSAT-2四极数据集在城市和农村环境中测试了新的分解。与常见的三分量分解相比，旧金山地区的分解表现出更高的双反弹散射和更小的市区体积散射。农村沼泽地的分解表明，体积与交叉极双反弹量之间的关系取决于植被密度。因此，我们建议，在可能的情况下，基于SAR的生物量估计研究应该使用由我们的分解计算的体积散射，而不是交叉极信号，后者也包含双反弹分量。
Common vegetation scattering theories assume that the synthetic aperture radar (SAR) cross-polarization (cross-pol) signal represents solely volume scattering. We found that this assumption is incorrect based on SAR phase measurements acquired over the South Florida Everglades indicating that the cross-pol radar signal often samples the water surface beneath the vegetation. Based on these new observations, we propose that the cross-pol signal consists of both double-bounce and volume scattering components. The simplest multibounce scattering mechanism that generates cross-pol signal occurs by rotated dihedrals. Thus, we use the rotated dihedral mechanism to revise some of the vegetation scattering theories and develop a fourcomponent decomposition algorithm with single-bounce, co-pol double-bounce, cross-pol double-bounce, and volume scattering components. We tested the new decomposition in both urban and rural environments using RADARSAT-2 quad-pol data sets. The decomposition of the San Francisco area shows higher doublebounce scattering and reduced volume scattering in the urban area with respect to the common three-component decomposition. The decomposition of the rural Everglades area shows that the relation between volume and cross-pol double bounce depends on the vegetation density. Thus, we suggest that, when possible, SAR-based biomass estimate studies should use the volume scattering calculated by our decomposition rather than the cross-pol signal, which also contains a double-bounce component.