I think the power of terragen is it's renderengine, but off course the entire program has got his own look. You could imitate the way of mapping (height distribution and stuff like that) in the vue material edditor You could import terragen terrains into vue... but the atmosphere and renderengine is the most important so I have to agree with Gebe after all: use terragen for a terragen look. Another idea that is used is to import a terragen render as background and use vue to add 3d object like plants and rocks in the foreground.