On the Study of the Geometric Properties of Historical Cartographic Representations

The long but partial and still open question of the geometric and projective characteristics and properties of early cartographic representations is revisited in view of the advancements in digital analytical and visual technologies that are now offered in a “part and parcel” operational environment, allowing a level of interactivity almost unthinkable even in the recent past. In this new technology frame, the geometric study of early maps is treated analytically via a typical two-dimensional comparison with relevant modern map counterparts or georeference. By bringing in the early map with a one-to-one correspondence to its modern reference, the comparison retains all those proper transformational steps that result in the visualization of map differences and, thus, the study of the geometric and projective properties of early maps. To illustrate the proposed process, two indicative examples are treated, related to two distinct schematic typologies of early maps: (1) a georeferenced map of the Ptolemy type, and (2) a non-georeferenced early map of the portolan type. A number of results related to these examples open a perspective for new pathways in the fascinating and adventurous field of map history.