Digital survey and 3D virtual reconstruction for mapping historical phases and urban integration of the fortified gates in the city of Pavia, Italy

Over the centuries, the fortified route of the city of Pavia has undergone different phases of construction, expansion and reconstruction of the defensive walls, adapting both to the requirements of modern military fighting techniques and to the urban expansion plans. Its fortified gates have been preserved in the succession of the different city walls, Roman, Gothic and Spanish ones, identifying fundamental elements in the urban structure, while the architectural configuration of each one has undergone intense changes. From the original eleven gates, only three remain visible today in a critical state of preservation and lacking a cultural enhancement despite their key position in the city. Through joint research and didactic activities, a digital documentation programme is ongoing on the remaining portions of Pavia’s walls, in order to document the state of preservation and to develop a preparatory knowledge to the integration of existing maps and virtual reconstructions. Starting from the data collected with close-range measuring instruments (Terrestrial Laser Scanner and UAV), a 3D modelling activity was carried out at the double architectural and urban scale. The 3D model of the architectural system was compared with historical photos and archival documents, to redefine in the digital space the construction and demolition phases of the monuments. These configurations were included in the spatial mapping of the historical centre and compared both with the current and historical urban asset, defining the role of the fortified ruins for the cultural promotion and military historical enhancement of Pavia.