First time posting an image on here...but I have been playing around with Terragen2 for awhile now.
For this image I originally intended to use Terragen2 entirely, alas I could not get the ice effect I had hoped for on the surface. I exported the terrain into world machine and eroded the surface a few times and then brought that into max. In max I used vray displacement to get the high res polygons without crashing my machine. I then used Vray to render the ice effect. The clouds and stars were all rendered with a camera match in terragen2. The final output was 3600x3600 so I had to render the clouds into 10 cropped strips on several machines at once and then recompile. Overall render time on the sky was 24 - 36 hours per strip.
Hope you like!
