UAV PHOTOGRAMMETRY FOR METRIC EVALUATION OF CONCRETE BRIDGE CRACKS

Abstract. Monitoring cracks opening on concrete bridges is a key aspect for structural health assessment. Digital image processing, combined with Unmanned Aerial Vehicles (UAVs) and photogrammetry, allows non-contact 3D reconstruction of cracks, reducing costs potential unsafe factors involved in manual inspections. This paper presents flexible procedure based UAV photogrammetry accurate evaluation geometry, that can be implemented periodic monitoring. Stereo-pair images, acquired UAVs close to the cracked surface, are used build scaled photogrammetric model through Structure-from-Motion. Cracks detected images by binarization digital processing techniques. Thereafter, one single reconstruct crack back-projecting coordinates object. built from current stereo-pair or an existing model, case monitoring set-up. Crack width accurately estimated world. The tested evaluated study, obtaining millimetric results, which line average ground sample distance employed. Results highlight potentials not only bridge inspections damages localization, but also evaluating geometry helping engineers assess structure conditions.