The graphic sign for historical narration of architecture. The fortifications of the Liri Valley

Communication by image is the most immediate and intuitive especially if based on the semiotic structure thus generating “meaningful images” that relate to the referent/signifier/signified. Starting from this assumption, the paper defines three levels of graphic communication that can be adapted to convey historical information about architecture. The three levels, therefore, generate as many graph- ic models that produce virtual, mental, and visual images, which relate geometries and colors with the certainty of historical data. The virtual model uses symbols to aid in the understanding of a large and complex real phenomenon. Its feature is denotative/metalinguistic and can be produced, for example, in a GIS environment. The mental model uses clues to visualize uncertain data such as hypotheses of the historical evolution of architectures or information drawn from written sources. It is a denotative model based on simplified monochromatic geometry. The visual model, also denotative, uses icons that reproduce the real object exactly as it is. The reproduced object has a textured or photorealistic visualization and therefore can communicate the certainty of the data. The defined procedure was applied to the case study of fortifications in southern Lazio.