a coarse detal elevation model derived from topographic maps with 25 m resolution is used for orthorectif cation. The horizontal error is therefore expected to be higher in alpine terrain. Additional ADSSD data were captured at the Crabengufer site in 2010. Due to the flight plan parallel to the slope. the ground sampling distance could be improved to 25 cm. The AIS data was interpolated to a raster with 1 m resolution and used for orthorectification Bahler et al. 2002: Hebi and Ginzler, 2012). The resulting high resolution orthophoto is called OP n hereafter.