Yes, I know this is a stupid projection. I just want it for personal reasons.
My goal is to print a world map poster with QGIS showing a different perspective on the world. What I need is an ordinary long-lat-projection but I want the upper part (North Pole) to be lola (0,0) end the bottom part (South Pole) to be lola (180,0) (that is poles on the equator). So basically Africa will be the top of the map, North Pole in the center and South Pole on the vertical center of the map's left and right borders.
I know the maths involved to transform the coordinates, but I would like to ask if it is possible to create a CRS (WKT?) from that mathematical coordinate transform. That so I don't try to do something that is not even possible. I find no examples of CRSes with mathematical (trigonometric) transformations online.
Best Answer
If I understand your need you don't need to transform coordinate, what you need to do is to change projection parameter to have north pole at center.
Look at this tutorial to see how it's done with an orthographic projection (in this case centered on Philippines not north pole).
To visualize what can be done by changing some projection parameter you can use this Map Projection Playground.
Below picture of the equirectangular (or plate carrée) and equal earth projection with the north pole at the center, reproducing your :
requirement. Just play with other projection to find one you like the most...