A computing model for the Pantheon's cupola: from the discrete to the continuos.The ideal continuous model.

In architectural surveys, the purpose of measuring is to individuate a finite number of significant points that significantly approximates the continuity of the real object, and which can be used to reconstruct a simplified geometric model. The choice of which points to survey is a sensitive procedure, to be performed during the planning of the survey by individuals capable of interpreting the object for its qualitative complexity. The reason for the existence of a form may have roots that are, to cite a few, geometric, perceptual, structural,or functional. The surveyors must, therefore, develop a critical reading of the building that draws from all the sciences and disciplines concerning architecture. They must also hypothesize a plausible model for the object understudy, and use measurement as a means for verifying the hypothesis. The introduction of new computer technology has some what inverted this process. The stereorestitution of digital images and three-dimensional laser scans currently makesit possible to capture an intermediate model that lies between the real objectand the geometric model, without there being any need to fully understand the object before commencing its survey. The study of the geometry of an object can be conducted using this intermediate model to advantage by working with the analytical tools provided by computer processing. This course of study is still open to exploration. The application presented here was conducted by the photogrammetry laboratory ofthe RA.D.A.A.R (Rilievo Analisi eDisegno dell'Ambiente e dell'Architettura) department of the University of Rome La Sapienza, and directed by Professor Mario Docci. It is part of a more comprehensive research project, coordinated by Professor Riccardo Migliari, which aims to define a methodology for architectural surveying using 3D laser scanning and software specific to the analysis of virtual models, in all senses of the word. The architectural object of this sample survey is the intrados of the Pantheon's cupola.