Aight, long time no post 
I am, believe it or not, still working on this… if anything the situation this year has put it ahead of traditional distractions (i.e. playing live music). Anyways, I try to hold off posting here unless I’ve got something decent to show, but after half killing myself this weekend I’ve got some fairly critical tests going:
Still pretty rough, but basically the idea is this:
Fitting rivers and roads to procedurally generated terrain is way hard, instead of doing it at the end, why not do it at the start?
Problem with doing it in a material though is that you have to then try and translate that displacement into world positions so that you can do things like travel down the river or drive along roads. This was unpleasantly difficult to figure out (made much worse by the fact that I forgot to turn sRGB off in my noise texture) but I seem to be getting it under control now
The test map is only 1k, but the idea is that I can just regenerate it on the fly in the lods of my planet mesh as they move around the surface making it basically infinite. As you can see at the start the base texture is just simple tetris shapes and lines and primitives (easy to generate), it’s the displacement that makes them look more natural.