Martin,
Good call. The Pines were my first outing using Xfrog so, my knowledge was limited.
The image sample below is an example of how the High Resolution Sugar Maple will render out-of-the-box.
There are images which can be used for various purposes. They include the base image (defused), normal image (which seems to work better than the displacement image) and specular image. The user can manipulate these as they feel necessary. Perhaps one day Terragen 2 will have a surface scatter shader function in the future.
The inset image is an example of using small displacement and translucence on the leaves. I opted not to use the specular image map however, users may want to experiment to achieve their own results. If you compare the leaves in the inset image with the full tree image you can see a more natural look. Using a small amount of translucence eliminates the strong contrast between light and dark transitions.
I hope this addresses your questions.
Marc
