Assessment of ASTER GDEM Performance by Comparing with SRTM and ICESat/GLAS Data in Central China

Recently, a new Global Digital Elevation Model (GDEM) from optical stereo data acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) was released with the resolution of 1 arc sec. In this study, the performance of the new ASTER GDEM is assessed by comparing with SRTM (the Shuttle Radar Topography Mission) and point data from ICESat/GLAS (Ice, Cloud, and land Elevation Satellite/Geoscience Laser Altimeter System). A 5 degrees x5 degrees area (30 degrees-35 degrees N, 110 degrees-115 degrees E) with varied terrain was chosen as the study area. Standard DEM-to-DEM comparison, DEM-to-control-point comparison and visual analysis were used to evaluate the ASTER GDEM quality. The results show that the ASTER GDEM has much fewer voids than SRTM V2 (the version 2 SRTM). The ASTER GDEM has lower elevations (approximately -5m) compared with SRTM, whereas the ASTER GDEM has higher elevations (approximately 15m) compared with ICESat/GLAS points. To the vertical accuracy, the results of the ASTER GDEM compared with SRTM V4 (the version 4 SRTM), SRTM V2 and ICESat/GLAS points are 39.55m, 25.99m, 33.99m at 95% confidence respectively, exceeding 20m estimated prior to the ASTER GDEM production. The poor accuracy may be related to the high terrain relief and high ratio of lower stack number of the ASTER GDEM in the study area. The ASTER GDEM shows better performance in the flat areas than that in the mountainous areas, and the accuracy improves with the increasing stack number. The ASTER GDEM has many artifacts including inland water noises and straight lines related to the irregular stack number boundaries, which are caused by the methodology to produce the ASTER GDEM.