Analysis and Geometric Modelling of Stellar Vaults of the Mediterranean Gothic in HBIM Environment

Survey and architectural representation, intended as moments in a path of knowledge, can connote themselves as processes aimed at the study of the rules that govern the formal principles of architecture. Surveying and drawing a vaulted system means researching its formal genesis, the construction procedures and the structural solutions that distinct it. In the study of vaulted systems, digital modelling defines a path of reinterpretation of formal genesis: by translating and revealing geometry as a principle generating form and idea, digital modelling emphasizes the heuristic function of drawing. This occurs only when the representation, and therefore the modelling, introduces a discretization of the form. Through the selection of some case studies of stellar vaults found in religious architecture in the city of Cagliari, the paper presents the application of procedural modelling processes in the BIM environment starting from the survey of point clouds acquired with 3D Terrestrial Laser Scanner technology systems (TLS). The experimentation of these processes on the historical architecture poses several challenges related first to the definition of the levels of knowledge of the building and to the modelling of the geometric components deriving from the survey. The objective of the paper is to trace a workflow that, overcoming the limits currently inherent in the local modelling of complex architectural elements in the BIM environment, introduces procedural modelling when it is not possible to resort to libraries of precompiled parametric objects that can be reused, as often happens in the so-called HBIM processes.