Creating custom projections with Proj4?

Question

I'm reading into how to customise projections with Proj4 - specifically to achieve tilted projections such as the example below (from vis4.net)

The Proj4 literature is pretty heavy going and having explored it I'm not clear which parameters I'd need to change, or whether a custom datum would need to be defined.

Answer 1

Define a tilted perspective projection (tpers) using:

• h: height (in meters) above the surface
• azi: bearing (in degrees) from due north
• tilt: angle (in degrees) away from nadir
• lat_0: latitude (in degrees) of the view position
• lon_0: longitude (in degrees) of the view position

Putting it all together, here is an example PROJ string for part of Europe:

+proj=tpers +ellps=WGS84 +h=5000000 +azi=30 +tilt=40 +lat_0=20 +lon_0=0