Thanks for your comments!
Inkydigit - some info
It's all vector displacement, no proceedural terrain, I grabbed a low res 3d model from Google Earth of the area and sculpted around that. Actually, I couldn't get any detail for the foreground area, so had to sculpt that from the photo reference, so I think I screwed up the scale a little. :-)
Used Maya and Realflow to add the grass (using fur) and water, and hand painted the snow masks for the mountain.
I thought it would be a challenge to recreate, espcially as the original photo has a nice overcast look, whilst still being quite punchy, but getting that in Terragen was quite difficult and made the image look very flat! So I went with a more directional look for the lighting.
Dune - no photos at all, just a lot of masks!