Bonino, BrigidaCabiddu, DanielaD'Alonzo, MattiaLupinetti, KatiaMortara, MichelaPittaluga, SimoneCampana, StefanoFerdani, DanieleGraf, HolgerGuidi, GabrieleHegarty, ZackaryPescarin, SofiaRemondino, Fabio2025-09-052025-09-052025978-3-03868-277-6https://doi.org/10.2312/dh.20253351https://diglib.eg.org/handle/10.2312/dh20253351This paper present a methodology for reconstructing and optimizing 3D digital models of complex, tangible underground heritage sites that are difficult to access or even closed to the public, with the ultimate goal of integrating them into interactive virtual reality experiences, both for preservation and to make them accessible to a wider audience. The approach is demonstrated through the complete digitization of Matera's Hypogeum, in southern Italy. Faced with the site's challenging conditions (i.e., intricate passageways, poor lighting, and physical constraints), we developed a specialized workflow that combines handheld laser scanning acquisition with optimized mesh processing, in order to produce a model that can balance details visualization and realism with performance efficiency when used in VR environments. A preliminary development of an immersive VR application is also presented to provide an initial qualitative analysis of the model.Attribution 4.0 International LicenseCCS Concepts: Computing methodologies → Mesh geometry models; Hardware → Scanners; Emerging interfacesComputing methodologies → Mesh geometry modelsHardware → ScannersEmerging interfaces10.2312/dh.2025335110 pages