Abstract
Many geoscientific computations are directly influenced by the resolution and accuracy of digital elevation models (DEMs). Therefore, knowledge about the accuracy of DEMs is essential to avoid misleading results. In this study, a comprehensive evaluation of the vertical accuracy of globally available DEMs from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Shuttle Radar Topography Mission (SRTM), Advanced Land Observing Satellite (ALOS) World 3D and TanDEM-X WorldDEM™ was conducted for a large region in Northern Chile. Additionally, several very high-resolution DEM datasets were derived from Satellite Pour l’Observation de la Terre (SPOT) 6/7 and Pléiades stereo satellite imagery for smaller areas. All datasets were evaluated with three reference datasets, namely elevation points from both Ice, Cloud, and land Elevation (ICESat) satellites, as well as very accurate high-resolution elevation data derived by unmanned aerial vehicle (UAV)-based photogrammetry and terrestrial laser scanning (TLS). The accuracy was also evaluated with regard to the existing relief by relating the accuracy results to slope, terrain ruggedness index (TRI) and topographic position index (TPI). For all datasets with global availability, the highest overall accuracies are reached by TanDEM-X WorldDEM™ and the lowest by ASTER Global DEM (GDEM). On the local scale, Pléiades DEMs showed a slightly higher accuracy as SPOT imagery. Generally, accuracy highly depends on topography and the error is rising up to four times for high resolution DEMs and up to eight times for low-resolution DEMs in steeply sloped terrain compared to flat landscapes.
Highlights
Relief plays a main role for numerous geomorphological, climatic, hydrologic and ecologic processes
The most recent dataset with global coverage is the TanDEM-X World digital elevation models (DEMs) TM dataset with a ground sampling distance (GSD) of 12 m, which is expected to be the new standard in geometric resolution and accuracy [6,7]
A direct comparison of the latest two ASTER Global DEM (GDEM) Versions was not conducted here, the results indicate that the last update of ASTER GDEM is not able to achieve the accuracies of the other global elevation datasets
Summary
Relief plays a main role for numerous geomorphological, climatic, hydrologic and ecologic processes. The most recent dataset with global coverage is the TanDEM-X World DEM TM dataset with a GSD of 12 m, which is expected to be the new standard in geometric resolution and accuracy [6,7] All of these DEMs usually are less accurate and capture less terrain details due to lower GSD in comparison to very high-resolution elevation models derived by stereo satellite imagery. These datasets normally have a higher GSD and vertical accuracy. They are often not suitable for larger areas, due to high cost and time-consuming processing.
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