The St. Michael fresco in the church of SS. Salvatore in Orsomarso (Cosenza, Italy). Documents and analysis of a 17th century architectural quadratura

The study presented concerns an architectural quadratura that frames the figures of the Archangel and two saints, painted in the church of SS. Salvatore in Orsomarso. The quadratura is conceived with the aim of shaping the space, at least partially, simulating an altar’s reredos with a very articulated architectural structure with three statues. The study is aimed both at documenting the fresco and at analyzing the perspective structure and illusionistic effects used by the author to ‘mislead’ the observer. This paper presents both the results of documentary research and the analysis of the fresco, through bibliography and artistic research, as well as the opportunities of the analysis of the fresco’s mesh. Specifically, the analysis was carried out both using traditional methods (direct observation and high resolution photos taken with a motorized panoramic head) and by experimenting with the analytical potential of the polygonal model (mesh), generated by digital photogrammetry based on SfM techniques. The ‘interactive’ visualization of the mesh (exploration, lighting, etc.) was able to encourage a ‘dialogue’ with the art work, allowing: to study the perspective’s structure of the painting; recognition and delimitation of day’s work (giornate); recording the irregularities of the plaster. The high resolution photographic texture, joined with the mesh, was indispensable to examinate the fresco’s perspective; while the same mesh, deprived of the texture and illuminated with a grazing light, allowes to recognize the irregularities of the plaster and the traces of giornate, amplifying the possibilities of investigation that are normally carried out in situ.