Computer Graphics World

February 2009 40 Does that mean the RenderMan group doesn't care about games? We care. But, if a game company buys RenderMan and uses it, they're doing it because they want feature-film quality for their games. CAD/CAM people use it, and universities have it. We listen to anyone who finds it useful. But clearly our direc- tion is dominated by the people who want the very best in quality, performance, and reliability. Reliability is a big one. ese films cost so much money, the one thing studios don't want is to find that it chokes. ey want their film to go through, they don't want to wait long for it, and they do not want any surprises. It's difficult. We're talk- ing about super-complex things. Are the multicore machines helping? ere are two kinds of forces. One is in the interactive loop where the studios want pictures as fast as possible. e other is when they want to render the whole mov- ie, and in this case, it's the total efficiency that counts. If you have to render 100 frames, the most efficient thing is to have each frame render per each processor, so each processor is going full out. So for the 100 frames, that's the most efficient way. But, if you're doing one frame, rendering with 100 processors isn't 100 times faster. You wish it were. So for that reason and because you're sharing disks and so forth, the efficiencies for a single frame start to go down. I'm not giving you solid answers. It's complex, and dealing with the complexity and tuning it for the rendering world is one of the things the RenderMan group is do- ing to take advantage of the architectures. You've got to follow the mainstream. When you think of what's driving Ren- derMan, do you still think in terms of photorealism? Well, when we started, we were using ani- mation to drive it for ourselves because we wanted to make animated films. But, we used reality for a number of years as a driver. At the time we started, the distance from what we were doing to reality was pretty far. We said that if we can match reality, then we will have control over the lighting, even though, as an animation company, we're not trying to do reality, we're trying to do some- thing different from reality. On that trash planet Wall-e is walking around, excuse me, gliding around, it's not reality, but on the other hand, it's very real. It's a different real. It's very hard to describe. But we use the dif- ficulty of reality to drive us forward. I remember for years and years I'd get up and give talks, and say the difference between the best computer graphics and what you see in front of you is a huge gap. I could show the best stuff from anybody, and then say, 'Look in front of you.' And the difference was marked. But I haven't been able to say that for a long time. It's kind of embarrassing that the credit frequently goes back to those of us in the early days. e bulk of the work and the heavy lifting was done by teams led by Tony for a few years and now by Dana for many years. ey've done extraordinary things. Dana is doing a phenomenal job of being responsive to what people need by pushing in new, important directions while being very practical. And, RenderMan has gotten very sophisticated in terms of the lighting model, the shading support, the multicore work, the shadowing, the deep shadowing. ere's been just an incredible amount of work, going beyond what we thought was possible. Beyond what you thought was possible? Oh yeah. I'm blown away. I see stuff now and think, 'You guys have really pushed this.' We used to talk about millions of polygons. We thought we were being adventuresome by picking this number. Now it's millions of hairs with a sophisticated lighting model on each one. It's just mind boggling. We look back on it now and say, 'Wow, that was just the beginning.' e really cool stuff was yet to come. But, it's never been about predicting, which you can't really do anyway. It has been about creating an environment in which people can do cool things. If we had set out to solve all the things we actually did solve, we might have gotten frozen. n Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net. (Left) Pixar's technical crew wrote sophisticated subsurface scattering shaders in PRMan to create the green aliens' volumetric, translucent material for "Lifted." (Right) Each character in "One Man Band" required several hundred shaders. Both shorts received Oscar nominations. n n n n Trends & Technology

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