典型山区SRTM3与ASTER GDEM数据精度对比分析——以青藏高原东麓深切河谷区为例
摘要
Digital elevation model (DEM) is one of the most important data format for geography research in mountainous areas. At present, the widely used digital elevation models include SRTM and ASTER GDEM. However, their relevant errors are not well distributed under the influence of different terrain types. For the accuracy analysis of these two types of data, this paper considers the 1:50 000 DEM and rivers as references to carry out experiments over the eastern Tibetan Plateau. The horizontal accuracy and vertical accuracy are evaluated respectively by using river- ravine deviation method and root mean square error method. The conclusions are drawn from this study as follows: (1) the average river-ravine deviation of SRTM3 is 127.8 m, of which the offset direction is southwest; while that of ASTER GDEM is 104.1 m, of which the offset direction is west; (2) absolute error distribution of SRTM3 is relatively concentrated, where the elevation error is 35.3 m, which is less than ASTER GDEM elevation error of 50.2 m. The overall vertical accuracy of SRTER3 is better than ASTER GDEM; (3) at high altitudes over the average elevation of 4500 m, there is a positive correlation between the error and the elevation, in which the SRTM3 error shows slower growth and higher vertical accuracy compared with ASTER GDEM; (4) the vertical accuracy of the two types obviously depends on the slope, with which the error approximately indicates an exponential curve growth, and the error of SRTM3 in the flat area is less than that of ASTER GDEM. This study helps to understand the error distribution of the two data sets in mountain areas as well as to provide a foundation for further studies in data selection and error correction.