Abstract
Synthetic Aperture Radar (SAR) interferometry technique generates digital elevation models (DEMs) and is used by various agencies widely. The recently released TanDEM-X DEM by DLR at 90 m spatial resolution is available for free download to users. This paper examines the accuracy of TanDEM-X DEM at different experimental sites with different topographic characteristics. Three sites were chosen, namely Kendrapara (Odisha), Jaipur (Rajasthan), and Dehradun (Uttarakhand) with plain, moderate, and highly undulating terrain conditions. The root mean square error (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 90 m 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 reveal that at Jaipur site with moderate terrain with urban and agriculture as major land use land cover (LULC) classes, the results of TanDEM-X 90 m DEM have higher accuracy than ALOS PALSAR RTC HR DEM. However, it is observed that in a predominantly plain region with agriculture practice (Kendrapara site, Odisha) and rugged region (Dehradun site, Uttarakhand) with mixed land use land cover (LULC) (e.g., forest, urban, streams, and agriculture) the results of ALOS PALSAR RTC HR data have higher accuracy than TanDEM-X 90 m DEM. Further, the study indicates that for a relatively plain site at Kendrapara (Orissa), CartoDEM V3 R1 DEM has the best performance with an RMSE of 1.96 m, which is the lowest among all DEMs utilized in the study.
Highlights
Digital elevation models are the primary input to terrain analysis or geomorphometry essential in various applications in hydrology, environment, and climatology
Ground control points (GCPs) collected through differential GPS (DGPS) survey technique are used for evaluation of digital elevation models (DEMs) at the experimental sites
The study indicates that for a relatively plain site at Kendrapara, Orissa, CartoDEM V3 R1 DEM has the best performance with an root mean square error (RMSE) of 1.96 m (LE90 = 3.22 m), which is the lowest among all DEMs utilized in the study
Summary
Digital elevation models are the primary input to terrain analysis or geomorphometry essential in various applications in hydrology, environment, and climatology. A large number of openly accessible DEMs are available for utilization in various models, which makes it essential to analyze the quality of DEM with quantitative accuracy assessments for best results. TanDEM-X is the latest DEM released by DLR at 90 m spatial resolutions. To prepare a global DEM with high accuracy, TanDEM-X mission utilizes the highly accurate orbits and baseline determination, while exploiting the InSAR capabilities of the two twin SAR satellites TerraSAR-X and TanDEM-X [1]. The parameters governing the selection of InSAR data pairs include view angle (ascending and descending pass), spatial or geometrical baseline, temporal baseline, time of acquisition, meteorological conditions, and coherence [2,3]. TanDEM-X DEM had systematic height errors like offsets and tilts in the order of some meters, which requires DEM calibration [4]
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