macro-scale map generation
I'm new to the space but I've been messing around with generating semi-plausible maps of entire planets lately. It's still missing a lot of features and tweaks I would like to have but it started looking like a map. So I wanted to share and maybe someone will have something to say, or point out problems. Each seed produces a completely different world of course but I just picked the one I liked.
My general approach is that I start with a sphere and add large-scale Voronoi cells to act as plates and rotate them around Euler poles (I don't do real drift, just calculate where they converge, diverge, or want to move in general). Then I subdivide these into sub-plates and alter the parent plate values just a bit for each to suggest old tectonic activity. Plate boundaries then get distorted and I map them into a much finer and more uniform Voronoi mesh (~50 km wide in the case of the images shown). This is the level where most of the calculations happen.
Terrain gets distorted based on a set of rules and the amplitude of plate collisions, creating mountain ranges and rifts. Plate movements then is also used to warp random noise patterns that are later added to the elevation.
Prevailing winds are basically copied from earth for now. They then drive ocean currents (blue arrows on the last image) using Stommel. Temperature starts as a simple gradient from the equator to poles that then gets dragged around by ocean currents and later winds. Oceans add moisture to the air based on this temperature and this also gets dragged around while turning into precipitation when climbing mountains, cooling down, or when hitting the zones where air lifts naturally. Precipitation turns into rivers that flow to lower cells or accumulate if they are in a dip in the land. This can create lakes that also evaporate and feed the second precipitation pass. I think I have too many huge lakes and inland seas right now but I wasn't able to fix it yet.
Precipitation and temperature are used on a lookup table of Whittaker-inspired biomes and these get drawn on a separate layer.
Finally, I rasterize the heightmap into a 5 km per pixel grid by turning them into a triangular mesh and then distorting the edges to make them less artificial-looking.
Does this make any sense? I mean, I like the look of the maps, but I don't know nearly enough about geology to tell if the are actually actually plausible.