Fool's Cap projection

[rschmunk]

I saw a toot on Mastodon tonight about the "Fool's Cap" projection, which seems to actually be a couple different projections shown within the face of a Renaissance fool, depending on the version you encounter. The art dates back to the late 1500s.

The original such illustration uses the Ortelius Oval projection, but the later version(s) do not. I'm trying to figure out what it or they might be. An example of the modified version can be seen on at e.g. https://www.rmg.co.uk/collections/objec ... 385#1445-2

This topic has been around long enough that there are multiple scholarly articles about it, but I'm not sure if any of them actually addressed the modified projection ID.

[daan]

The variant you link to is something along the lines of the modified ptolemaic projection used by Waldseemüller in his very famous 1507 map of the world as the first showing “America”.

Cheers,
— daan

[rschmunk]

Yes, very similar, but not quite the same. The Bonne projection with phi_TS at about 17°N unsurprisingly also looks very similar.

[rschmunk]

This could be one of those "the only way to determine the projection is to somehow duplicate a distorted scan of a centuries-old publication". Which is always tons of fun for carto nerds. If you get 90%+ of the way there, you can claim la victoire.

[daan]

Many of the 16th century projections were ad hoc. I don’t know if that exact one shows up in other contexts. I can speculate on what influenced its design, but I don’t know of any description for its construction.

— daan