A potential compromise is generation of a coarse raster or vector map of the planet, with details provided procedurally and/or stored as vector data. Simulations can
work with the data as required, retrieving coarse data and generating details as required. The generation process, as it stands in my head, would work something like this:
Stage 1: Continental Shape Generation
|Continental plates generated with my experimental code - send to stage 2!|
This is what I was experimenting with several months ago. A supercontinent land mass is created from a stochastically-generated polygon that is then split into continental plates that are shifted. I also experimented with some of the ideas from the Experilous web site but in raster form, as well as some techniques from Soon Tee Teoh's 2008 paper "River and Coastal Action in Automatic Terrain Generation". Only the continental shapes and plate data are required from my current experiment, for input to the next stage.
|From Teoh "River and Coastal Action in Automatic Terra|
Stage 2: Planet Generation
|Screenshot of Experilous planet generator|
Stage 3: Mountain Generation
|From Hnaidi et al. "Feature based terrain generation using diffusion equation"|
|From de Carpentier and Bidarra "Interactive GPU-based procedural heightfield brushes"|
Stage 4: Hydrology Generation
|From Genevaux et al. "Terrain generation using procedural models based on hydrology"|
Techniques from Genevaux et al. ("Terrain generation using procedural models based on hydrology"), Teoh, or Amit Patel could be used here. Additional terrain generation may occur after/as part of the hydrology work.
|Example terrain generated from demo on Amit Patel's website|
What Comes AfterBiological and sociocultural simulations could follow. This could lead to villages, towns, cities, and nations being formed. That would likely require at least some additional storage, although procedural techniques can again be used to help reduce the storage requirements. There's no need to retain extensive detailed geometry for every building in every city across the globe.
More thoughts later. I may go see the new Star Wars movie and review it.