Digital documentation of complex architecture through 3D point clouds, BIM, and virtual reality: the baroque church of Popoli (Italy) as a case study

The digital documentation of complex architectural heritage requires integrated workflows capable of combining metric accuracy, geometric interpretation, semantic modelling, and accessible forms of visualization. This paper presents a reproducible Scan-to-HBIM workflow for the documentation and dissemination of the “Holy Trinity” in Popoli, Italy, a Baroque building characterized by a central plan, a shallow spherical-cap dome, rich decorative surfaces, and indoor–outdoor survey constraints. The methodology integrates static terrestrial laser scanning and UAV photogrammetry to generate a complete and metrically reliable point cloud, which is then used to support geometric analysis, HBIM modelling, and immersive visualization. Particular attention is given to the dome, whose surveyed geometry is compared with an idealized spherical-cap model in order to assess its regularity, identify deviations from the theoretical form, and guide the modelling abstraction. The resulting HBIM model is structured through levels, sections, geometric primitives, and customized BIM families, and is exported in interoperable formats for visualization and information management. Two complementary dissemination strategies are also examined: a virtual tour based on equirectangular panoramic images acquired during the laser scanning survey, and a BIM-based virtual reality environment enabling interaction with semantic building components. The results demonstrate that the proposed workflow supports accurate documentation, geometric understanding, and accessible communication of complex heritage architecture, providing a useful framework for conservation, management, and public dissemination.