Planet tech info from Dr Ross:
Where before we had a generator for rocky surfaces and one for ice surfaces which both took Stellar Forge inputs, we now have terrains and terrain materials of various different types and scales which are deterministically selected and blended together depending on the Stellar Forge driven properties of that planet.
Landable planets are still classified between rocky, icy, rocky ice, high metal content and metal rich depending on what emerges from the Stellar Forge simulation, but their terrains are dependent on those simulation values more than these discrete titles. Terrain shapes, styles, and combinations are mixed together, meaning there is a lot of variation within these classes.
As with everything in Elite Dangerous, the planets are full sized, and so it is a challenge to ensure that the resources we make work on all scales, work with each other, and provide detail all the way from orbit to the surface. I think we’ve done a grand job selling the scale of these things.
Across a planet there is now a large scale mask processed which determines different zones of types of terrain based. The mask depends on things like how gravitationally stressed the planet is, the crust thickness and if the planet is, or has been, tectonically active. These zones mask out further subzones of terrain and material types, and follow the flow patterns laid out by the layer above it, creating a seamless landscape across the planet.