Polarimetric synthetic aperture radar (SAR) tomography (Pol-TomoSAR) can be used for global forest digital terrain model (DTM) and canopy height model (CHM) mapping with high spatial and temporal resolution at low economic cost. However, the performance of DTM and CHM inversion in current Pol-TomoSAR methods is often compromised when the ground-to-volume ratio (GVR) is low, which usually happens in complicated terrain where large negative slope angles are commonly present, or in dense tropical forest where the ground visibility is low due to strong attenuation by the dense vegetation layer. In this work, a novel method for the separation of ground and volume scattering, aiming at robust and accurate DTM and CHM inversion in dense tropical forest and complicated terrain, is proposed. By fully exploiting multibaseline polarimetric SAR data, the proposed method can perform a more effective separation of ground and volume scattering. Subsequently, by applying the SAR tomography technology on the separated ground and volume scattering, the proposed method can retrieve accurate DTM and CHM information even at low GVR areas. Numerical experiments conducted on both simulated data and P-band airborne F-SAR data show that, compared to the most commonly used two-component algebraic synthesis method, the proposed one has a much better performance in terms of separation of ground and volume scattering. Furthermore, the inversed DTM and CHM present better agreement with light detection and ranging (LiDAR) measurements, especially in large negative slope angle terrain where the GVR is rather low.

中文翻译：

---

多基线极化SAR数据中地面散射和体散射的分离及其在DTM和CHM反演中的应用


偏振合成孔径雷达（SAR）断层扫描（Pol-TomoSAR）可用于全球森林数字地形模型（DTM）和冠层高度模型（CHM）测绘，具有高空间和时间分辨率，且经济成本低。然而，当前Pol-TomoSAR方法中的DTM和CHM反演性能在地体比（GVR）较低时往往会受到影响，这通常发生在通常存在大负坡角的复杂地形或密集地区由于茂密植被层的强烈衰减，地面能见度较低的热带森林。在这项工作中，提出了一种分离地面和体散射的新方法，旨在在茂密的热带森林和复杂地形中实现鲁棒、准确的DTM和CHM反演。通过充分利用多基线极化SAR数据，所提出的方法可以更有效地分离地面和体散射。随后，通过将SAR层析成像技术应用于分离的地面和体散射，该方法即使在低GVR区域也能检索准确的DTM和CHM信息。对模拟数据和P波段机载F-SAR数据进行的数值实验表明，与最常用的二分量代数综合方法相比，该方法在地面散射和体散射的分离方面具有更好的性能。此外，反演的 DTM 和 CHM 与光探测和测距 (LiDAR) 测量结果具有更好的一致性，特别是在 GVR 相当低的大负坡角地形中。