Revisualizing Ptolemy's Geography

Revisualizing Ptolemy’s Geography uses modern Geographical Information Systems (GIS) and statistical visualization to explore this unique dataset. In doing so it hopes to bring to light structural phenomena that may tell us more about its sources and construction. One of the key methods used is to derive linear maps automatically from the coordinates themselves. Ptolemy’s great contribution to cartographic science was the separation of geographic data from its representation. By providing tables of geographic coordinates, rather than embedding them in commentaries as his predecessors had done, he was able to transmit a picture of the world that could be depicted in different ways according to the needs of the geographer and their audience. Today we still marvel at the apparent accuracy of a work that stretches from Portugal to China, but easily forget that beyond the visual impact of the medieval maps which survive, there exists a remarkable resource in the raw coordinate data that form their basis.