Comparative evaluation of vertical accuracy of elevated points with ground control points from ASTERDEM and SRTMDEM with respect to CARTOSAT-1DEM

Abstract In this study, vertical accuracy of Shuttle Radar Topography Mission (SRTM DEM ) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER DEM ) was compared to CARTOSAT-1 DEM of Roja village of Shahjahanpur District of Uttar Pradesh, India. Vertical accuracy analysis between SRTM DEM and ASTER DEM with respect to CARTOSAT-1 DEM (IRS-P5) allowed a quantitative/qualitative assessment of the vertical component of the error, while statistical measures were used to evaluate the performance of the DEM. The original SRTM image contained voids which were represented digitally; such voids were initially filled for obtaining accurate vertical height from DEM. Results shows that SRTM based measurements of ground control points (GCPs) exhibits root mean square error (RMSE) of 186.65 m while ASTER DEM based measurements exhibits and RMSE of 137.65 m. This indicate that ASTER DEM outperforms SRTM DEM in detecting vertical accuracy. Average relative root mean square error (R-RMSE) of twenty GCPs was 1.0 and 1.25 for ASTER DEM and SRTM DEM , respectively. Comparison of vertical accuracy of points from ASTER DEM with respect to CARTOSAT-1 DEM exhibits an Coefficient of determination (R 2 ) of 0.59, normalized root mean square error (N-RMSE) of 1.26, mean absolute error (MAE) of 30.82 and RMSE% of 6.3. These vertical accuracy results show that the vertical accuracy of ASTER with respect to CARTOSAT-1 DEM shows a better agreement than SRTM DEM for selected 20 points from orographic plain. This study shows that SRTM DEM is not appropriate over the settlement (city/village).