DEM Generation based on UAV Photogrammetry Data in Critical Areas

Many Geomatics technologies based on the use of terrestrial and aerial sensor offer a significant support and new potentialities in term of quickness, multi-scale precision, cost-cutting, and in short, sustainability. The 3D data and mapping products, above all the large-scale ones derived from aerial acquisitions (e.g. Unmanned Aerial Vehicles, UAV) can be gradually adopted even when the context is not enough accessible or standard airborne data does not fulfill the requested resolution and accuracy. Starting from the availability of large scale UAV data, the paper is mostly purposed to examine the use of tools aimed to generate DEM (Digital elevation model) from DSM (digital surface model) obtained from UAV flights. In literatures many application concern the point cloud data generation from aerial photogrammetry or airborne laser scanner. Several different filtering approaches and algorithms (filtering point along density, direction, slope) are used to derive bare-Earth, but in the test case, the high level of detail of objects, together with the complexity of high slope of ground impose some adaptation. The test is included in a decision-making processes concerning the promotion of Alpine landscape leaded through a project of sustainable mobility. Therefore the DEM generation is used to foresee a possible and sustainable path of the railway rack, achieved by a simple multi-criteria analysis performed by Geographic Information Systems (GIS) tools. In the end an important aspect of the test is the use of open source GIS tools employed in the experience