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June 24, 2005
Mt. Stripmore
Here's a little image I worked up last night. It was really just a feasiblity test for a new landscape technique I was experimenting with. I'm actually working on another image altogether, and for that one I'll need to have a statue/monument rising out of the mountains in the background. In the final image, she will be clothed (at least partially) and holding a spear or some other exotic polearm, all still made from stone. However, for here I just needed her as a placeholder, so I didn't bother to clothe her or decorate the pole at all. As a result, she looks a bit like a pole-dancing stripper.
Thus, I give you:
For those of you interested in such things, the technique was amazingly simple. In fact, it was so simple I was pretty sure it wasn't going to work well or perhaps not at all. On top of that, I'd seen no mention of it in any of my newsgroup search queries. But nonetheless, I think it worked very well.
I positioned several cylinders of varying height in my scene, and then draped a large cloth over them. I altered the cloth properties to make it extra stretchy, and it draped down fairly convincingly. The rest of the effect is just bump maps and color ramps driven by a combination of the Z value (i.e. elevation) and the face normal (i.e. slope). Thus, the high steep areas got a brownish-white color and a very harsh turbulence bump map, while the lower and flatter areas got a greenish color with a softer bump map.
The green still doesn't have the vegetation look I'm after, but it's probably good enough for the eventual image. Remember, this is really just going to be in the background. On the other hand, I can be a bit of a perfectionist on these trivial details. I won't even tell you how long I spent working out a starfield texture once. But here, I think the key is to switch more fully to a more convicing soft bump map when I get to the green, and I just now realized that one good way to do that would be drive the switch not off the elevation and slope, but to drive it off of the color change itself which was driven off those things. It would be very similar, but I could make the change much more sharply just by measuring the green component of the color ramp. I'll have to try that one over the weekend.
I might also play with turning the bump map into a displacement map. It would make for a longer render, but I think it would make the ridge lines look better. (For the unitiated, bump maps give the appearance of bumps via false self-shadowing while displacement maps really do make bumps which then cast real shadows.)
The statue got a little bit of the bump map further down, but then it transitions into another bump map I'd develped before: stucco. From a distance, it looks just like a pocked/weathered stone. (Though in the future, I'll probably want to tone down the specular channel.) I also have some ideas for making the mountain-to-statue transition areas a bit better.
The clouds in the background are the only bitmap texture in the entire scene. Everything else is procedural. That's important to me, because when I render something hi-res for printing, bitmaps that are good enough for screen rendering sometimes show artifacts at 300 dpi. Plus, with some of my hi-res renders, I'm having a hard enough time keeping the whole mess under the 2GB application memory limit as it is without adding a lot of unnecessary bitmap textures to the mix.
Anyway, it was just a feasibility study, but I thought it came out well enough to share.
Render by Dan at June 24, 2005 08:31 PM