Projective geometry and iconographic interpretation

The gnoseological role of image description is one of the central themes of all those disciplines that, in general, deal with images or pictorial works. In particular, in the field ofarchitecture and architectural history, the studies of architecture in both painting and drawing(architectura picta) has gotten over the years an amplitude and a conspicuous importance.The iconographic interpretation of painted scenes, containing architectural subjects or urban backdrops, with the use of descriptive geometry as a comprehensive theory of drawing based onmathematical principles, far from being considered as a mere rhetorical exercise, appears still one ofthe fundamental ways of critical analysis of the image. Particularly for those depictions informed onintellectual conception of perspective representation spread from the Renaissance onwards. In the studies of that representations only the geometry (projective or descriptive) seems able to provide the accuracy required and understanding to distinguish probable from improbable configurations.The geometric restitution of perspective in painted representations, dealt with strict graphic method,highlights a series of controversial issues that, in operational practice, are frequently resolved with aphilological reconstruction often far from the structure and metrical properties of spatial objectsgraphically represented. In particular this happens in the geometric restitution of some curves (ellipses, arcs, etc.) related to homological transformations that are hardly drawable properly on the image – which is not a vector form – even with the help of computer aided design tools.