Tilting a map?

[Wired]

I've got a map (for the sake of the example just lets take Earth), and I'm trying to adapt it to an 90° axial shift. Unfortunately, my brain has hit a road block trying to compute the how of this, since just turning it in PS turns the landscape to a portrait format, obviously. How do I go about adapting the lay of the labd and the position and form of the landmasses???

[waldronate]

You need to reproject the image. You should be able to do it with GDAL's gdalwarp tool. You're looking to go to the Cassini projection ( https://en.wikipedia.org/wiki/Cassini_projection ) because you want a pole at the equator.