This is a Terragen 2 render. Original size : 2000 x 1200. Rendertime : 22 hours with a Q6600 and 3 go ram. The terrain used is a DEM file, « Grand Canyon West », enhanced with procedural strata and various displacements. A lot of materials layers here, and 5 Xfrog vegetation populations. Two layers of clouds : high cirrus and low level volumetric cumulus. I spent a lot of time looking for the best point of view on this one. Realism was the challenge here. I never really saw the Grand Canyon, but I used much photographic documentation found on the Net.
I hope you will like it. Thanks for your comments, criticism and help.