So when you see the video after the break, your will probably get the same idea as me,"that has got to be fake". But hey, Unreal Engine forum member by the name of koola released screenshots from his latest project, fully procedural ground textures.
He mentiones that big rocks come from the Epic Kite Demo. In the past this member, koola, already has shared very realistic real-time architectural visualizations using Unreal Engine 4.
Anyway, I'll shut up and have you all just see for yourselves. Here some extra links UE4 - Substance designer and UE4 - Substance designer. This Unreal project is just Unreal, amazing.