PSI - Issue 78

Caterina Balletti et al. / Procedia Structural Integrity 78 (2026) 1823–1830

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Fig. 1. View of Fiumefreddo Bruzio (Cosenza), Italy

3.1. Geometric multi-sensor and multi-scale survey The geometric survey of Fiumefreddo Bruzio employed a multi-sensor, multi-scale approach to meet the needs of both seismic risk engineers and cultural heritage managers. The workflow began with an analysis of available cartographic resources (orthophotos, regional maps, digital model terrain), which informed the design of a geodetic control network anchored to IGM95 vertices via 40 GNSS benchmarks in NRTK mode (RDN2008/UTM 33N). Field operations were concentrated into a coordinated three-day campaign, integrating terrestrial and UAV photogrammetry, static laser scanning (FARO Focus S120), and mobile SLAM mapping (Stonex X120GO) to ensure comprehensive 3D documentation. A DJI Mavic 3 quadcopter was used to capture 8,850 nadiral and oblique RGB images at about 2 cm ground sampling distance. Additionally, 3,500 terrestrial photos (Nikon Z7, 20 mm lens) covered the narrowest streets and façades, achieving sub-centimetre detail. SLAM mapping supplemented data collection in UAV-inaccessible areas, and five key buildings - Castello di Valle, Santa Maria de Andexis, Santa Chiara, San Rocco, and Addolorata - were surveyed at 1:50 scale and <1 cm uncertainty. Data processing involved orienting photogrammetric blocks using structure-from-motion, integrating point clouds from all sources in a unified reference frame. The resulting multi-resolution dataset supported the creation of a full colour urban orthophoto (Fig.2), digital terrain model DTM (Fig. 3a), digital surface model DSM (Fig. 3b), contour maps, continuous textured mesh at urban scale (Fig. 4), façade orthophotos, architectural drawings at 1:50 scale, and high-resolution orthophotos of castle frescoes. This integrated approach yielded a metrically accurate, information-rich 3D model supporting both seismic vulnerability analysis and informative applications for tourism. 3.2. Streets and paths mapping Starting from the dataset available on OpenStreetMap, the street graph was constructed. The OSM graph proved rather limited, with many segments - especially pedestrian or restricted traffic areas - absent. Therefore, the graph was augmented through the survey described in Section 3.1, incorporating not only the width of streets and paths, but also the presence of potential points of interest relevant to civil protection (e.g., medical clinics, police stations). Fig.5 presents the mapping of routes, indicating the type of segment (pedestrian streets, pedestrian streets accessible to cars only for residents, driveways, tracks).