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 (SRTMDEM) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTERDEM) was compared to CARTOSAT-1DEM of Roja village of Shahjahanpur District of Uttar Pradesh, India. Vertical accuracy analysis between SRTMDEM and ASTERDEM with respect to CARTOSAT-1DEM (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 ASTERDEM based measurements exhibits and RMSE of 137.65 m. This indicate that ASTERDEM outperforms SRTMDEM in detecting vertical accuracy. Average relative root mean square error (R-RMSE) of twenty GCPs was 1.0 and 1.25 for ASTERDEM and SRTMDEM, respectively. Comparison of vertical accuracy of points from ASTERDEM with respect to CARTOSAT-1DEM exhibits an Coefficient of determination (R2) 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-1DEM shows a better agreement than SRTMDEM for selected 20 points from orographic plain. This study shows that SRTMDEM is not appropriate over the settlement (city/village).