Accuracy assessment of digital elevation models (DEMs) plays an important role in facing their use in geoscience applications. This study investigates the vertical accuracy of most recently published versions of global DEMs over Croatia: 1 arc-minute global relief model (ETOPO1), Global 30 Arc-Second Elevation (GTOPO30), SRTM30+, Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010), Altimeter Corrected Elevations 2 DEM (ACE2 DEM), Shuttle Radar Topography Mission GDEM (SRTM GDEM), and Advanced Spaceborne Thermal Emission and Reflection GDEM (ASTER GDEM). Geodetic ground control points (benchmarks) allowed the comparison in terms of vertical accuracy. Additionally, the differences between models in the identical points were determined and analysed after adjusting the models to the same resolution. The results have yielded information about the overall accuracy of models; the accuracy depending on height, land cover, and slope; presence of large and systematic errors; and mutual agreement between the models.Overall vertical accuracies according to the root mean square error over Croatia are: ETOPO1 27.6 m, GTOPO30 21.6 m, SRTM30+ 21.3 m, GMTED2010 7.4 m, ACE2 DEM 4.5 m, SRTM GDEM 3.8 m, and ASTER GDEM 7.1 m. The highest accuracy was shown by SRTM GDEM version 3, which is far better than the previously released versions. All models have proved to be worse in the rough and forest areas, whereas in flat and barelands, new-generation global DEMs SRTM GDEM, and ASTER GDEM are highly accurate.
IntroductionIn the past decade, global digital elevation models (global DEMs) have become invaluable sources of information in geosciences (e.g. Raaflaub and Collins 2006;Toutin 2008). Global DEMs have been significantly improved in comparison with those first released in the mid1990s, Global 30 Arc-Second Elevation (GTOPO30) and 1 arc-minute global relief model (ETOPO1), with the new-generation model releases, the Shuttle Radar Topography Mission GDEM (SRTM GDEM) in 2007, with a resolution of 3 arc seconds, and the Advanced Spaceborne Thermal Emission and Reflection GDEM (ASTER GDEM) in 2009, with a resolution of 1 arc second. As all models deviate from reality, global DEMs are usually used without an estimation of their accuracy and reliability and without considering errors that can affect results (Wechsler 2003). The goals of this work were to quantify and compare vertical accuracy, assess dependence between vertical accuracy and topographic characteristics (land cover and slope), and assess the differences between all global DEMs that were published from the mid-90s over Croatia. Testing of global DEMs was done for most recent versions of