Reframing the “H” in HBIM: from systematic review to UML-based conceptual modeling

As Heritage Building Information Modeling (HBIM) emerges as a key digital approach for documenting and managing architectural heritage, its conceptual basis and technological scope remain fragmented due to ambiguity in defining the "H" as "Historic," "Historical," or "Heritage." Additionally, current HBIM implementations are predominantly limited to conventional surveying tools, such as terrestrial laser scanning and photogrammetry, with minimal adoption of immersive, semantically rich, and interactive technologies. This paper clarifies the definitional scope of HBIM, systematically investigates integrated heritage information across structural, material, historical, artistic, and conservation dimensions, and proposes a unified UML-based schema integrating HBIM with Smart Point Cloud (SPC) technology. Further, we introduce a comprehensive four-stage Architectural Heritage Information Infrastructure (AHII), emphasizing semantic enrichment, interoperability, and advanced Gaussian Splatting visualization, thus positioning HBIM as a dynamic node within an inclusive digital heritage ecosystem.