Sorry Stiglr, I've been away for a while (no, not at a lunatic asylum as you may think, it was a
research asylum
).
When I run into a similar problem a few years ago, what I learned is:
1 - terrain:
- generate a square lattice large enough (I used 8x8 but the finer, the better)
- subdivide it once or twice (a matter of taste)
- select its vertices
- apply a moderate amount of noise to X and Z
- apply a larger amount of noise to Y
- adjust manually the points where you want your hills to be
- commit subdivision
- select all vertices
- apply a smaller amount of noise to Y (to provide some roughness)
- select the whole object and reduce it until it's of your liking (you don't want to have 64E10 triangles, do you?)
- the texture you apply is determinant to make it palatable.
2 - trees and bushes
- drawing them yourself is a pain in the neck and takes way longer then you expect if you want them to look natural, but you may find several pretty good (and
free) ones on the web (try sharecg.com) in .obj format. Not all of them are decently textured but that's something you can take care of yourself.
3 - foliage
That's a huge headache and you risk ending up with incredibly large files unless you make intensive use of transparency and bump textures - 2 or 3 coarse shells around each tree, the rest to the texture. Even better if your final software can handle real displacement textures rather than just bump.
That's all for now, but let me know if you have a problem, I might have already bumped my head against it.
P.S.: if you don't find any decent ready-made trees just whistle, I should still have a couple of them in some corner of my HD.