Scan-to-BIM Process and Architectural Conservation: Towards an Effective Tool for the Thematic Mapping of Decay and Alteration Phenomena

Ancient monumental complexes need continuous analysis and monitoring operations to preserve a good conservation status. For this reason, the analysis of decay and alteration phenomena repre-sents one of the main activities for their preservation. At the same time, the diffusion of Heritage Building Information Modelling (HBIM) methodology opens new scenarios for the management of Architectural Heritage. The paper describes the workflow based on a Scan-to-BIM approach for the generation of a decay map in an HBIM model. The workflow was applied to a significant case study, the church of “Santa Maria della Grotta” in Marsala (Italy). This church, partially excavated in a sandstone bank, is part of a larger heritage site consisting of a series of hypogea and a Punic ne-cropolis dating back more than a thousand years. The Scan-to-BIM process, relying on an integrated survey combining mobile laser scanning and photogrammetric technologies, enabled the achieve-ment of a complete 3D parametric model of the monument and, altogether, a detailed decay map in a BIM environment. The mapping process focused on the production of thematic maps of perimetral walls according to an abacus of decays implemented in a BIM system, useful for the analysis and conservation of the church. The work demonstrates how the Scan-to-BIM process is an efficient approach for 3D data collection and how it could facilitate the identification and mapping of pathogenic phenomena. Furthermore, the inclusion of this kind of information in the BIM model represents an effective tool for the maintenance and restoration of built heritage.