Supporto all’analisi costruttiva per gli edifici storici: applicazioni del reverse engineering al rilievo del patrimonio costruito. Construction analysis support for historical buildings: applications of reverse engineering to Cultural Heritage survey

Reverse engineering is a process in which an existing object is studied to understand how it works and potentially improve it. In the field of Cultural Heritage, 3D scanning and parametric modeling tools have made it possible to use the typical reverse engineering approach to study and understand historic buildings. This paper presents a method for studying the displacements and deformations that have occurred in historic masonry buildings over time using Terrestrial Laser Scanning (TLS) and parametric modeling. The proposed workflow is divided into three stages: digital survey, computational 3D modeling, and comparison of the deformed and undeformed configurations. The digital survey creates a 3D point cloud, referred to as the “Basic 3D Model” (B3M), which accurately represents the current condition of the building’s structural elements. The point cloud is then reconstructed as a 3D NURBS topological model, and specific visual programming algorithms are used to restore the hypothetical deformations that have occurred over time to their original state. This model is called the “Ideal 3D Model” (I3M) because it represents the theoretical, undeformed configuration of the structures. By comparing the I3M and the B3M, the structural behavior of parts of the building can be determined, and the overall condition of the building can be evaluated to guide improvement interventions. The method has been applied to several case studies in Italy, including the masonry columns and the masonry facades of the Basilica of San Domenico in Siena and the timber trusses of the Teatro Comunale in Bologna, Italy.