Multi-Resolution digital 3D imaging system applied to the recording of grotto sites: the case of the grotta dei cervi

The Grotta dei Cervi is a complex and fragile Neolithic cave where human presence left a large number of unique pictographs and petroglyphs. Detailed documentation necessitates recording it at different levels of details or spatial resolutions. A general approach would entail a combination of 3D data from different 3D sensors and information from different sources in order to meet set resolution targets. We used a prototype multi-resolution 3D laser imaging scanner that allowed acquiring the shape information of the three main chambers with a spatial resolution that improves with shorter standoffs. The system can record 3D data at a camera-to-object distance which ranges from 0.5 m to 10 m. At a standoff of 0.75 m, it provides a depth uncertainty of 0.08 mm and an optical lateral resolution of 0.2 mm on actual rock surfaces. This paper presents the project and the results obtained. The 10-day long visit into the Grotto generated more that 100 GB of 2D and 3D data that requires the development of new tools for modelling and managing the archive.