Das Projekt "Evaluation of the terrain model influence on the Orthorectification of Sentinel-2 satellite images over Austria (S2OrthoQDTM)" wird vom Umweltbundesamt gefördert und von Technische Universität Wien, Department für Geodäsie und Geoinformation (E120) durchgeführt. Aim of the project is to address the concerns on Sentinel-2 geolocation accuracy over the area of Austria. Within Austria's alpine region steep slopes occur. This means that errors in terrain model elevation have a severe effect on lateral displacement, as displacement because of elevation error and because of slope can add up. Errors are expected from SRTM due to radar shadows (InSAR viewing geometry) and other effects. Output of the project is a report, which assesses the geolocation errors expected because of PlanetDEM for the area of Austria. This will be compared to geolocation errors to be expected with a terrain model of superior quality. Errors of the superior model are not determinable, it will act as reference ('ground truth') for PlanetDEM. A second, equally important, output is a suggestion on how to improve the geolocation quality of Sentinel-2 data over Austria. Possibilities on how to improve the product will be discussed. Next to repeating the orthorectification pocress with a better DTM and thus derive a new orthoimage, the grid-shift mechanism5 will be explored, as it might be used for on-the-fly transformation within a GIS. Practical consequences of using the different options will be explored.