Accuracy of Dem Genaration from Terra-aster Stereo Data

In this work we studied the accuracy of DEMs generated from ASTER stereoscopic images by automated stereo-matching techniques with two different softwares (OrthoBase PRO and OrthoEngine). We compare several DEMs generated for a test area of 23 km x 28 km situated in the province of Granada (south Spain). This is an area was selected because its variable and complex topography with elevations ranging from 300m up to 2800 m. The method is based on the photogrammetric principle of collinearity in orienting the images, for which purpose 15 control points were used. The accuracy was studied using 315 ground check points whose coordinates were determined by differential GPS. Results indicate that elevation root-mean-square error (RMSE) equals 13 m, which is less than the pixel size (15 m). We think that it is satisfactory for many cartographic and analytical applications comparable to that of conventional topographical maps. It is particularly important to have abundant and accurate check control points available since this determines the reliability of the quality control itself. Finally, we compare accuracies between both TERRA–ASTER DEMs and DEMs elaborated from conventional 1:50.000 topographical maps of same area.