UAV-based photogrammetry as an integration in multi-sensor architectural survey

Current methodologies used in architectural surveys allow to obtain 3-D models featuring high precision for geometry and shape and good quality for chromatic data. Several researches are available in bibliography, showing how easily high-precision models, with high-quality photorealistic textures, can be obtained by using and combining laser scanning and terrestrial photogrammetry. Anyway, there are some contexts in which achieving good quality surveys with these techniques is logistically complex, such in the case of areas with difficult or no access (roofing, high façades, etc.). In many of these cases, a solution can be found in an innovative survey methodology, which is becoming more and more popular: Unmanned Airborne Vehicle (UAV)-based photogrammetry, with processing of data via Structure from Motion (SfM) procedures. The present paper describes a study of the integration of different survey methodologies (laser scanning, ground- and UAV-based photogrammetry, total station) in order to obtain a full featured 3-D model, whose accuracy has been checked.