The accuracy of a DEM derived from ASTER data using differential GPS measurements

ASTER is a high-spatial resolution, multispectral imaging system flying aboard TERRA, a satellite launched in December 1999 as part of NASA’s Earth Observing System (EOS). An ASTER scene covering 61.5 km x 63 km contains data from 14 spectral bands. An ASTER Digital Elevation Model (DEM) is generated using bands 3N (nadir) and 3B (backward) level 1A images acquired by the Visible Near Infra-red (VNIR) along-track stereo data in the spectral range of 0.78 to 0.86 microns. The aim of this study is to assess the accuracy and reliability of a 15m spatial resolution DEM generated from ASTER data. Ground Control Points (GCPs) are used to establish an accurate relationship between a projected image, the sensor, and the ground. The quality of the DEM will depend both on the accuracy of the GCPs and on their number. This assessment is carried out by verification of the DEM against a number of check points (CPs) collected independently from GCPs and acquired using differential GPS. This was undertaken in a semi-arid region of Jordan. The results show that ASTER DEM with 15 m spatial resolution has the majority of height differences of less than 20m and the best potential accuracy for the DEM from ASTER using the root mean square error (RMSE) is about ±9.42 m. Further work will focus on the accuracy of an InSAR derived DEM over the same area and the implications of these elevation models for hydrological process modelling in the region.