Technical aspects related to the application of SFM photogrammetry in high mountain

Structure-from-Motion (SfM) photogrammetry is a flexible and powerful tool to provide 3D point clouds describing the surface of objects. Due to the easy transportability and low-cost of necessary equipment with respect to laser scanning techniques, SfM photogrammetry has great potential to be applied in harsh high-mountain environment. Here point clouds and derived by-products (DEM's, orthoimages, Virtual-Reality models) are needed to document surface morphology and to investigate dynamic processes such as landslides, avalanches, river and soil erosion, glacier retreat. On the other hand, from both the literature and the direct experience of the authors, there are some technical issues that still deserve thorough investigations. The paper would like to address some open problems and suggest solutions, in particular on regards of the photogrammetric network design, the strategy for georeferencing the final products, and for their comparison within time. The discussion is documented with some examples, mainly from surveying campaigns at the Forni Glacier in Italian Alps.