Orientation of archive images on 3D digital models of painted vaults: an interesting tool for restorers

Over the last years, the area of conservation and enhancement of cultural heritage has benefited from new surveying methodologies. In particular, laser scanners and the latest evolutions in digital photogrammetry and processing software based on structure from motion and multi-view stereo algorithms allowed to achieve 3D models of the status quo whose features include precision suitable for restoration scales and high-quality textures. Besides methodological and technical issues, another key requirement for any intervention on this kind of buildings is their full, in-depth knowledge, which includes building design, modifications’ timeline, current conditions, present-day and historical causes of degradation etc. In this view, surveys are a valuable asset for the investigation of historical sources. The present work investigates historical photographic sources, focusing on the possibility of orientation by means of photogrammetry techniques, which provides an additional texture layer as a support tool for historical analysis. The paper displays a case study featuring the availability of a reference survey, which allows validation of the results, and two other cases highlighting the importance of this kind of documents to restoring teams.