Page 134 - AC/E Digital Culture Annual Report

134currently illegible, making them easier to discern through an interactive viewer, and results in important documentation and conservation work. This documentation also makes it possible to assess future erosion processes and devise preventive conservation measures.Medieval mosaics of the church of San Michele In Africisco (Ravenna, Italy)As previously mentioned, RTI (Re ectance Transformation Imaging) technology has proven to be of great interest in surfaces where the visual perception may vary depending on where we view them from. An example is the tests48 carried out as part of the Digital Materiality research project at the Digital Humanities Lab49 in Basel, which was focused on a medieval mosaic from the former church of San Michele in Africisco (Ravenna, Italy). Dated to AD 545 and now housed in one of the rooms of the Bode-Museum in Berlin, it belongs to the type of Byzantine mosaics made of coloured tesserae, which created an impressive shimmering e ect when light fell on their surface. This was an important factor in deciding to use RTI, as this technology would allow a digital model of the mosaic to be obtained, preserving the re ective properties of the surface, with their changing colours and golds. For this process severaldozen photographs were taken while arti cial light was shined onto the mosaic’s surface from di erent directions under the supervision of the team. The digital models obtained using this technology, examined through an interactive RTI viewer,50 are therefore a much more accurate replica of the original than any other type of two-dimensional digital image could be.With respect to conservation, the aim of captur- ing these RTI images was to use them to identify areas whose structure and re ective properties di ered from others owing to the presence of tesserae of a di erent size or shape or di erently set, suggesting that they are the product of some type of repair or restoration carried out during the turbulent history of this mosaic from SanMichele in Africisco. One of the team’s goals is to conduct the same experiment on mosaics in situ.1.6 Robotics and Drones/UAVsOne of the di culties often encountered in digitally documenting immovable propertyis the structural limitations that hinder the access of people and the use of the best-known techniques mentioned above, such as 3D laser scanning or photogrammetry. Nevertheless, advances in robotics and arti cial intelligence are increasingly coming up with alternative ways of surveying such places.ROVINA projectAn example of the foregoing is the ROVINA project.51 Funded by the European Union’s 7th Framework Programme, it is aimed at developing autonomous mobile robots to make monitoring archaeological sites faster, cheaper and safer.The test-case scenario for ROVINA was the catacombs of Priscilla (Rome) and San Gennaro (Naples), two sites with certain risks owing to the presence of a maze of underground tunnels and areas possibly contaminated by gases (Calisi et al., 2016).52For this project a robotic system called DigiRo was developed to digitise the archaeological sites. It was tted with motion sensors anda laser telemeter to establish the distancesof particular objects. Three RGB-D cameras capable of capturing surface colour and depth were used to obtain three-dimensional digital images of the various objects or surfaces. Finally, the data gathered by the robot was stored in the cloud, where an archaeological information system (ARIS)53 analysed and processed all the data through the collaborative platform. These archaeological sites can thus be e ectively monitored and conserved, as digital documenta- tion can be used to prevent damage or restore cultural heritage.1. DOCUMENTATION, DIAGNOSIS AND CONSERVATIONThe use of digital technologies in the conservation, analysis and dissemination of cultural heritage