Digital reconstruction after disaster: what seems to be lost

The case study we are presenting in this article is the Church of San Salvatore in Campi di Norcia. The church was built between the ninth and fifteenth centuries in the Romanesque and Gothic periods, and is a very important example of Benedictine architecture in Valnerina. It was completely destroyed by the recent earthquake that badly affected most of the region’s cultural heritage. The only surviving information comes from a “virtual tour” uploaded by a local photographer on the Google Earth platform, which shows the church in January 2016. Additional information was also gathered from (non-spherical) pictures taken by other photographers with reflex cameras. The spherical photos (obtained by stitching together four pictures taken with a reflex camera with an 8 mm lens, rotated around a nodal point), processed in Agisoft Photoscan, were used as the basis for modelling the whole building with a dense point cloud. The digital model was validated using topographic measurements taken on site from the surviving masonry. This digital model was used as a reference to develop an Historic Building Information Model (HBIM). To create the HBIM (and particularly the various parts of the vault) research into the invariant parameters and the geometric genesis that led to the current appearance of the building was required. This reverse process represents the core of this research: the reconstruction following the disaster aims not only to search for the form of the lost heritage, but also to discover the cognitive processes that generated it.