Ptolemy's map of Greece

A reconstruction of the 10th map of Europe from Ptolemy's Geography, showing Ancient Greece in the Roman era (c. 150 AD).
Full size map on deviantart.com: https://www.deviantart.com/ancientgreekmaps/art/Ptolemy-s-Ancient-Greece-1151394170

The map is meant to be an exact visual representation of Ptolemy's text, not an artistic reconstruction like the medieval maps based on his work. I was inspired instead by similar work at LacusCurtius

A few places where I had to make subjective changes not in the text:

  • The region boundaries are drawn according to a nearest neighbor algorithm as their position can't be determined more precisely than that. 
  • The text usually only provides coordinates for the start and end points of rivers, and I had to tweak the river courses a little to avoid paradoxes like a river going through a mountain, which would happen often if I just drew a straight line between the river's two endpoints. 
  • mountains are usually not assigned to regions in the text, so if I show that Mount X is in a certain region, that just means that it's closer to a town of that region than to towns of any other region. 

But aside from these issues, it's supposed to be a one-to-one mapping of the information present in the text into a visual form, nothing more or less.

I rescaled the longitudes by 1.428 (see wikipedia for why this might make sense), as otherwise the Greece map would look terribly distorted by horizontal stretching. Some regions like Thessaly's Pelasgia look too thin even after this transformation.

Coordinates:

The text I used for the coordinates was based on Karl Müller's edition of Ptolemy, and only later did I realize that they often differ from the more commonly used coordinates of both the "Xi" and "Omega" versions of Ptolemy's text. Some of these changes in the positions didn't seem really justified, and I couldn't figure out where he got his coordinates from. I was also surprised to discover that 1 in 4 places on the Greece map have different coordinates in the Xi and Omega versions, and in other regions this gets even worse with 1 in 3 places having conflicting data. The Xi version has so many obvious errors that it's basically unusable for drawing a map, while the Omega version is much better, but it still requires extensive data cleaning to turn it into a presentable map. The Karl Müller edition on the other hand uses a seemingly random mix of Xi and Omega coordinates and also many additional changes, and could be plotted on a map without making any further corrections - clearly this was an already curated dataset. But it made me wonder how much of what I'm drawing is just guesswork by Karl Müller and other modern scholars, and how much of it actually resembles what Ptolemy drew 2,000 years ago.

Example of coordinate differences: blue arrows point to the Omega position, red arrows to the Xi position, and purple when the Omega and Xi are the same yet different from Karl Müller's.


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