calico: You're right, the bark looks a bit too strange. This issue is a texture-related problem. I think a good solution is to remap the entire trunk with a custom built texture, then re-render it. I'll try to do that.
FrankB: Yes, a high AA value increased rendertimes painfully, especially for the sky, with all those cloud layers rendered without acceleration cache. However it helps to bring out a lot of subtle details that the default AA doesn't visualize so good, especially with far grassblades, stone displacement ecc. I'll post the full res version when I'll have the finished image
njen: Thank you very much for your hint about the foliage displacement, I never thought about it and I think I'll try. The lack of shadows is also caused by the sun heading, that almost follows the render camera direction. I set it like that beacuse tree and sky are rendered separately from the rest of the scene, so shadows could not interact between the two parts of the image. I'll try working on levels to get a contrast enhanced version that helps to get out some more detail on grass and tree foliage, something like this
Thank you all for the very helpful hints!
