ISPRS-Annals ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences ISPRS-Annals ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci. 2194-9050 Copernicus Publications Göttingen, Germany 10.5194/isprsannals-I-4-181-2012 EVALUATION OF ASTER GDEM VER2 USING GPS MEASUREMENTS AND SRTM VER4.1 IN CHINA Li P. 1 Shi C. 2 1 Li Z. 3 Muller J.-P. 4 Drummond J. 3 Li X. 5 Li T. 1 Li Y. 6 Liu J. 1 GNSS Research Center, Wuhan University, Wuhan, China State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, China COMET+, School of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK Mullard Space Science Laboratory, Department of Space and Climate Physics, University College London, UK Zhejiang University, Zhejiang, China School of Geodesy and Geomatics, Wuhan University, Wuhan, China 20 07 2012 I-4 181 186 Copyright: © 2012 P. Li et al. 2012 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://isprs-annals.copernicus.org/articles/I-4/181/2012/isprs-annals-I-4-181-2012.html The full text article is available as a PDF file from https://isprs-annals.copernicus.org/articles/I-4/181/2012/isprs-annals-I-4-181-2012.pdf

The freely available ASTER GDEM ver2 was released by NASA and METI on October 17, 2011. As one of the most complete high resolution digital topographic data sets of the world to date, the ASTER GDEM covers land surfaces between 83<sup>°</sup>N and 83<sup>°</sup>S at a spatial resolution of 1 arc-second and will be a useful product for many applications, such as relief analysis, hydrological studies and radar interferometry. The stated improvements in the second version of ASTER GDEM benefit from finer horizontal resolution, offset adjustment and water body detection in addition to new observed ASTER scenes. This study investigates the absolute vertical accuracy of the ASTER GDEM ver2 at five study sites in China using ground control points (GCPs) from high accuracy GPS benchmarks, and also using a DEM-to-DEM comparison with the Consultative Group for International Agriculture Research Consortium for Spatial Information (CGIAR-CSI) SRTM DEM (Version 4.1). And then, the results are separated into GlobCover land cover classes to derive the spatial pattern of error. It is demonstrated that the RMSE (19m) and mean (-13m) values of ASTER GDEM ver2 against GPS-GCPs in the five study areas is lower than its first version ASTER GDEM ver1 (26m and -21m) as a result of the adjustment of the elevation offsets in the new version. It should be noted that the five study areas in this study are representative in terms of terrain types and land covers in China, and even for most of mid-latitude zones. It is believed that the ASTER GDEM offers a major alternative in accessibility to high quality elevation data.