3D GEOMETRIC ANALYSIS OF THE FAÇADES OF GOTHIC BUILDINGS IN VENICE: EXAMPLES OF 3D MODELLING

The Photogrammetry laboratory at CIRCE is conducting a research campaign to identify a procedure for survey and representation of warping on the façades of Gothic-era Venetian buildings. With respect to an ideal plane, the warpings can be caused by to two different sources: the first, the object of this research, involves a hypothesized “entropiombo ” of design, in other words, a deliberate slope of the plane of the facade inward. This hypothesized design warping is added to the second reason, represented by the warpings due to subsidence and settling, either local or generalized, of the buildings which always appear in Venetian structures. The result is a complex geometric configuration which is quite difficult to read. The studies conducted till now have resulted in very important observations relating to the individual cases, but a comprehensive investigation has not been done on a statistically consistent sample of façades, which could help identify construction "customs". To date, the geometric analyses have been based on a model of the warpings achieved by a substantial number of vertical and horizontal profiles, selected in the most relevant areas of the façade. Survey by topography or photogrammetry proved to require an inordinate amount of resources, which is why the investigations have always involved a fairly limited number of buildings. Today, the availability of laser-scanner instruments have made it possible to reduce the acquisition times of the data and automate extraction of the profiles, but most importantly, have made it possible to create a descriptive 3D model of the surface