Document Type : Research Paper
Authors
1 M.Sc. in geographical information system, University of Tehran
2 M.Sc. in remote sensing and geographical information system, University of Tehran
3 M.Sc. in remote sensing and geographical information system, Islamic Azad University
4 M.Sc. in remote sensing, University of Isfahan
Abstract
Abstract
Digital Elevation Models (DEM) enable researchers to perform geographical researches on a global and regional scale such as global changes, natural disasters, environmental hazards, environmental monitoring, etc. Therefore, DEM data plays a key role in scientific researches. SRTM and ASTER GDEM are two elevation datasets that cover nearly the entire land surface of the earth and are globally available (for almost 80% of the earth). Thus, it is necessary to evaluate the vertical accuracy of such data prior to their use and to select the appropriate data considering the research target. ASTER-based digital elevation model has spatial resolution of 30 meters, which seems to provide more precise elevation data than SRTM with 90 meters spatial resolution. Several studies have been performed for evaluating the accuracy of each of these two datasets in various countries of the world. The results of such studies indicate their advantages and limitations over each other. In this study, the vertical accuracy of these two DEMs are evaluated by ground control point in three zones of Iran with different topographic characteristics which are East Azerbaijan, Sistan and Baluchestan and Bushehr. Results show that the RMSE of SRTM as the index of error for the study area in East Azerbaijan, Sistan and Baluchestan and Bushehr are 6.1, 7.4 and 2.9 meters and in ASTER GDEM are 8.7, 8.3 and 7.2 meters respectively. Therefore, the vertical accuracy of STRM is higher than that of ASTER GDEM in all three zones. In this research, the relation between vertical error and land characteristics including slope and direction of slope has been studied and the results have been presented. The final findings of the research indicate higher vertical accuracy for SRTM compared to ASTER GDEM in Iran and it is concluded that SRTM is a more appropriate choice for various applications.
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