Page 180 - AC/E Digital Culture Annual Report

180structural problems stemming from the geologi- cal di erences in the land on which it stands and earlier restoration work.Although traditional methods and technologies detected major structural issues from the outset in the façade and side chapels, the use of new technologies identi ed abnormalities not visible to the naked eye owing to their location in physi- cally inaccessible areas of the church, such as the part of the vault concealed behind the corniceof the nave or micro ssures in the ceiling, which required the use of a quadcopter, a type of un- manned aerial vehicle (UAV) that incorporated a camera and a Wi-Fi system with remote control by smartphone. A 3D laser scanner was used to evaluate each of the structural deformations and cracks. Together with the information gleaned by the quadcopter, it made it possible to produce a considerably detailed and complete geometric plan of the church.The data collected was used to carry out an in-depth study by means of a thorough analysis of digital models. Compared to other traditional techniques, this process makes it possible to evaluate deteriorated materials and structural modi cations that were taking place, including those that could be potentially serious in the future.The application of technologies to acquiring digital models of heritage assets also has an experimental aspect that is currently proving to be very fruitful in recovering lost art historical elements. This aspect has aroused the interest of the academic community, especially in the eld of archaeology, though research of this kind is increasingly being carried out on other types of historic heritage. The current appearance of many of our monuments di ers from that ofthe past, but today, thanks to the possibilities of experimentation and digital recombination that 3D digital models provide, it is possible to convey their past appearance based on surviving records, achieving truly unique and hitherto unseen recreations of heritage.Equirectangular images and projection mappingIn this connection, Zaragoza University has run a pioneering project to return the chapel of the Monument (or of San Marcos) of Zaragoza cathedral to its height of splendour (Monzón, 2015).267The chapel was remodelled in the eighteenth century to house the Holy Week Monumentin its interior. The architectural and sculptural richness of the portal, and the Baroque layout of the staircase and the complex painted backdrop canvas (no longer extant) which acted as a mock altarpiece that concealed the Monument are signi cant elements that can be studied using new technologies.In this case reverse engineering techniques were used to document the chapel graphically and geometrically, namely 3D laser scanning and photogrammetry.268 The importance of using these metric techniques in documenting heritage compared to photography and traditional sur- veying techniques was highlighted here, as they are very accurate at recovering lost elements and obtain data that can be processed digitally to produce elevations, cross-sections, pro les and maps of damage enabling a diagnostic study over time to be carried out.The data gathered was used to create a 3D digital model of the interior, the portal and the nave where the chapel is. The equirectangular images obtained from photogrammetric tech- niques were employed for this purpose to gather better graphic details.In addition, a proposed layout was designed for the chapel using projection mapping to highlight architectural features of the chapel by means of light. Images, textures and videos showing earlier states or emphasising elements of its sculptural iconography were projected onto the portal. The most important use to which projection mapping was put was to create a ctitious restoration3. RESEARCHThe use of digital technologies in the conservation, analysis and dissemination of cultural heritage