Wondered if ay of you knew a german company called 3D Reality Maps that proposes photorealistic 3d maps.
They have a demo for one of their Alps map on Youtube

There are other demos on their map product pages (try the Alps ones).

I found this quite impressive and very detailed and wondered how difficult this would be to make it in Vue.

They use aerial photographs for the textures and thus have every color shift at the right area. They probably also use it to distribute trees or rock objects in the landscape.

Fantasy pictures, free 3d models, 3d tutorials and seamless textures on Virtual Lands.