GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 ___ GNGTS 2023 Fast and low cost methods for SfM independent remote sensing: resolution, scale and errors mitigation in some study cases. A. Pesci 1 , G. Teza 2 , F. Loddo 1 1 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna. 2 Alma Mater Studiorum University of Bologna, Department of Physics and Astronomy. Keywords : Remote Sensing; Surveying; Photogrammetry; SfM. Abstract Fast, simple and low-cost surveying by means of Structure-from-Motion photogrammetry (SfM) is a powerful chance for detecting surface variations, possible warning conditions, observing interesting morphological changes in the frame of emergency times or long-time planned projects. The availability of intuitive software packages especially designed to satisfy a wide range of users makes it possible to extend the use of these survey techniques also to non-expert researchers. Basically, it runs following some operational steps aimed at aligning captured images and running the photogrammetric restitution that is transforming 2D data in 3D surface models. The simplest is the method the more important is the evaluation of performances in terms of model resolution and precision as well as mitigation of possible systematic effects. This contribution deals with the description and discussion of some case studies were a free and fast approach aimed at evaluating the reliability of the results was used. The considered case studies are (see full references): 1) SfM-based survey of a rock cliff by means of a prosumer camera at long distance led to the extraction of accurate point clouds and suggest a relation between internal precision and GSD (about 2.5), proposed in Pesci et al. (2020); 2) Experiments based on the acquisition of artificial, self-made targets, designed to study SfM model accuracy, led to the estimation of thresholds (Fig.1) for resolutions (Pesci et al., 2020);