Integrated Geomatics for Urban Heritage: Reconstructing Gubbio’s Fragmented Medieval Walls Through Data Fusion

Urban-scale heritage structures subject to progressive disappearance require multiscale documentation approaches integrating archival evidence with contemporary geospatial data. Medieval defensive circuits exemplify this challenge: originally continuous perimeters spanning kilometres undergo centuries of demolition and urban transformation, leaving scattered remnants embedded within modern cities. This study presents a three-phase framework applied to the Mura Urbiche of Gubbio (Italy), a fortification circuit of approximately 3 km consolidated between the 12th and 14th centuries. Historical cartographic hypothesis and nineteenth-century cadastral records were georeferenced in QGIS using Thin Plate Spline transformations, reconstructing three diachronic circuits and identifying 16 cadastral parcels accounting for an estimated 2 km (66%) of the original perimeter. Targeted architectural-scale acquisition combined UAV photogrammetry with SLAM-based mobile mapping, producing a hierarchically registered, multi-resolution point cloud via ICP co-registration. A Scan-to-HBIM workflow applied to the Gate of Sant’Ubaldo stretch (the oldest preserved sector and active structural monitoring site) yielded a semantically enriched model representing three-leaf masonry stratigraphy and monitoring sensor locations. The study outlines how architectural-scale survey can, in future work, be used to refine territorial hypotheses and inform updates to cadastral representations, and how a PostGIS-based environment could support long-term interoperability between survey data, conservation documentation, and structural health monitoring streams.