I'm probably revealing the world's best kept secret, but I imagine their technical blueprint and engine code works something like this: You should also note the varying levels of elevation in the game which can be used as occlusion blockers. The ONLY stuff that is happening (AI, animals, side missions, local audio) is…
mip maps on veg...depending on engine (that ole caveat)...its very important usually to get a good and consistent texel density to start with that and having the code LOD the mips at the correct distance/ angles anistropic solve so many of these issues i miss it... :-(