Assessment of vertical accuracy for TanDEM-X 90m DEMs in plain, moderate and rugged terrain

SAR Interferometry technique generates digital elevation models (DEMs) and is being used by various agencies widely. The recently released TanDEM-X DEM by DLR at 90m spatial resolution is available for free download to users. This paper examines the accuracy of TanDEM-X DEM at different experimental sites having different topographic characteristics. Three sites were chosen namely Kendrapara, Orissa; Jaipur, Rajasthan and Dehradun, Uttarakhand with plain, moderate and highly undulating terrain conditions. The RMSE were calculated using ground control points (GCPs) collected by Differential GPS method for experimental sites at Dehradun, Jaipur and Kendrapara. The accuracy of TanDEM-X 90m datasets is compared with other openly accessible optically derived DEMs (ASTER GDEM V2, CartoDEM V3 R1, AW3D30) and InSAR derived DEMs (SRTM, ALOS PALSAR RTC HR). The RMSEs reveals that at Jaipur site with moderate terrain having urban and agriculture as major LULU classes, the results of TanDEM-X 90m DEM has higher accuracy than ALOS PALSAR RTC HR DEM. However, it is observed that in predominantly plain region having agriculture practice (Kendrapara site, Orissa) and rugged region (Dehradun site, Uttarakhan) with mixed land use land cover (e.g., forest, urban, streams, and agriculture) the results of ALOS PALSAR RTC HR data are having higher accuracy than TanDEM-X 90m DEM. Further, the study indicates that for relatively plain site at Kendrapara, Orissa; CartoDEM V3 R1 DEM has best performance with an RMSE of 1.96m, which is least among all DEMs utilized in the study.