Some days ago I was thinking "how would I store the real world into a continuous game level ?".

I guess it must have been some challenge for RockStar engineers (for GTA 4 or Red Dead Redemption) or when developing RAGE (the ID game, not the rockstar engine), and I wonder how they solved it.

Of course current RAM and hard disk capacities don't allow it if you don't use high definition content, so you simplify by abusing the reuse of objects:

* Use doodads for trees, barriers, bushes, benches, trashbins, etc
* Use palettes instead of textures for the ground and walls and buildings
* Use heightmaps for altitude
* Use procedural method for modeling roads, houses, buildings, sidewalk, pavement
* Also use procedural methods to model the insides of buildings: walls, ceiling, stairs, doodads.

These are the only things which make sense to me, but I want to know if they are other methods I'm missing, like for example reducing vertex precision while storing models, but requiring to make an exporter.