TanDEM-X双站InSAR地形提取及精度评估

Generating and Evaluating Digital Terrain Model with TanDEM-X Bistatic SAR Interferometry

在介绍TanDEM-X/TerraSAR-X SAR数据获取模式和零秒时间基线等双站干涉测量优势的基础上,提出了一种基于TanDEM-X双站SAR数据的高精度地形提取方法,并利用ICEsat激光测高数据进行了精度评估。该方法采用引入外部DEM进行相位差分的策略,减少相位残差,提高相位解缠精度与效率。另外,在双站模拟相位和地理编码过程中考虑到双站几何结构和零时间多谱勒时间参数,采用ICESat高程数据进行绝对相位偏移校正。以复杂地形环境下的普若岗日冰原为例,获取了空间分辨率10m、高程精度0.8m的DEM结果,精度可满足国家1∶10 000地形制图的要求。

The paper introduces the bistatic SAR system of the TanDEM-X/TerraSAR-X,especially focusing on its flexible data acquisition model and the special advantages of a zero-time baseline.We present a bistatic InSAR processing method for DEM generation with TanDEM-X/TerraSAR-X data,highlighted by aphase difference strategy as a means of differencing bistatic interferograms and simulated phase from an external DEM,e.g.SRTM DEM.This strategy reduces the residual phase and improves the efficiency and the precision of phase unwrapping.We take account of the bistatic geometry and the corresponding zero Doppler time in SAR interferometric processing.The absolute phase offset was calibrated with some external ICESat points.A case study was carried out to generate the DEM product over the Puruogangri Ice Field in the Tibetan Plateau.Compared with the SRTM-X DEM and ICESat elevation,our preliminary results demonstrate the great potential of the TanDEM-X bistatic InSAR technology for mapping surface topography.