Abstract
The global digital elevation model (DEM) is important for various scientific applications. With the recently released TanDEM-X 90-m DEM and AW3D30 version 2.2, the open global or near-global coverage DEM datasets have been further expanded. However, the quality of these DEMs has not yet been fully characterized, especially in the application for regional scale studies. In this study, we assess the quality of five freely available global DEM datasets (SRTM-1 DEM, SRTM-3 DEM, ASTER GDEM2, AW3D30 DEM and TanDEM-X 90-m DEM) and one 30-m resampled TanDEM-X DEM (hereafter called TDX30) over the south-central Chinese province of Hunan. Then, the newly-released high precision ICESat-2 (Ice, Cloud, and land Elevation Satellite-2) altimetry points are introduced to evaluate the accuracy of these DEMs. Results show that the SRTM1 DEM offers the best quality with a Root Mean Square Error (RMSE) of 8.0 m, and ASTER GDEM2 has the worst quality with the RMSE of 10.1 m. We also compared the vertical accuracies of these DEMs with respect to different terrain morphological characteristics (e.g., elevation, slope and aspect) and land cover types. It reveals that the DEM accuracy decreases when the terrain elevation and slope value increase, whereas no relationship was found between DEM error and terrain aspect. Furthermore, the results show that the accuracy increases as the land cover type changes from vegetated to non-vegetated. Overall, the SRTM1 DEM, with high spatial resolution and high vertical accuracy, is currently the most promising dataset among these DEMs and it could, therefore, be utilized for the studies and applications requiring accurate DEMs.
Highlights
Digital elevation model (DEM), containing the basic information about the topographic features representing the actual Earth’s surface [1]
ASTER GDEM2 and AW3D30 DEM were obtained by photogrammetric methods using stereo data, but Shuttle Radar Topography Mission (SRTM) DEM and TanDEM-X DEM were generated by interferometric synthetic aperture radar (InSAR)
The assessments of the vertical accuracy of the six DEMs using high-precision ICESat-2 altimetry points show that SRTM1 is significantly better than other DEMs (Figure 2), while the statistics accuracy of the AW3D30 DEM is closest to that of SRTM1 DEM, and the result is in agreement with
Summary
Digital elevation model (DEM), containing the basic information about the topographic features representing the actual Earth’s surface [1]. The development of Earth observation technologies brought a variety of global or near-global scale digital elevation models (DEMs), including SRTM DEM [7], ASTER GDEM2 [8,9], AW3D30 DEM [10] and TanDEM-X DEM [11,12,13]. ASTER GDEM2 and AW3D30 DEM were obtained by photogrammetric methods using stereo data, but SRTM DEM and TanDEM-X DEM were generated by interferometric synthetic aperture radar (InSAR).
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