HR LOD based HBIM to detect influences on geometry and shape by stereotomic construction techniques of brick vaults

The use of construction techniques in cloister vaults in noble buildings, as covering elements for square or rectangular rooms, is widespread across Europe. The geometric continuity at the intrados makes generally possible the execution all over the span of frescoes, stucco and decorations, with a great diffusion of a great variety of solutions. The construction of brick vaults, from the late Middle Age, was sped up by limiting the centring to the wooden planks arches that were instrumental in the profile determination. Starting from laser scanning, photogrammetric and thermographic techniques, the punctual reconstruction of the geometry and construction techniques allowed to recognise and understand the constructive richness, the multiplicity and unicity of each vaulted element, made of recurrent elements and specific features, thus sketching a mixed pattern of workers and highlighting the constructive knowledge of ‘stereotomy’ applied to the brick block vaults. Nowadays, the availability of several BIM-based modelling procedures and tools based on high detailed surveys allows to identify and reconstruct the shape, drawing reliable assumptions about the construction methods and the execution time. The research methodology here proposed intends to tackle an updatable geographic catalogue, able to transfer the construction richness, inheriting the historic lesson of French ‘repertoires’ to generate modern HBIM vault libraries ( abaci ). The paper focuses on a well-documented case, the Magio Grasselli palace in Cremona in which the cloister vaults of two main rooms, and others, show different construction systems embodied by the geometry. The methodology has shown how the cloister vault typology can be turned to a dome construction in the same vault, and how ‘stereotomy’, the capacity of skilled workers to control the space, modified the typical geometry, made by the ‘generative’ construction process used for the cloister vault (intended as the intersection of 2 barrel vaults), turning it into a dome in the upper part, giving back a sort of morphing, merging the two different generative rules (dome and vault) as described hereafter and creating unexpected scenic effect.