Computer Graphics World

Twenty years ago, Pixar Animation Studios released a shading language, an interface, and a specifi cation called RenderMan, a collection of "tools and systems that would let thousands of people create pictures of whatever they chose to design," as Pixar's Ed Catmull put it then. And indeed, studios around the world have used RenderMan to create hundreds of fi lms, many of which have won Oscars for visual eff ects and for animation. In 1993, Catmull, Loren Carpenter, Rob Cook, omas Porter, Pat Hanrahan, Antho- ny A. Apodaca, and Darwyn Peachey received a scientifi c and engineering award from the Academy for the development of RenderMan software. In 2001, Catmull, Cook, and Car- penter received an Academy Award of Merit for "signifi cant advancements to the fi eld of motion-picture rendering as exemplifi ed in Pixar's RenderMan." Catmull has also re- ceived Academy Awards for subdivision sur- faces and digital image compositing. is month, at the Scientifi c and Tech- nical Awards presentations, the Academy is bestowing its Gordon E. Sawyer Award, an Oscar statuette, to "Ed Catmull, a computer scientist, co-founder of Pixar Animation Studios, and president of Walt Disney and Pixar Animation Studios, for his lifetime of technical contributions and leadership in the fi eld of computer graphics for the motion- picture industry." Below, Catmull discusses the evolution of RenderMan and its impact on the CG industry. What was the original goal for Render- Man? We wanted to do something that was going to last for many years, so we had, let's say, three main goals. One of them was to think about extreme complexity. We set a goal of being able to manage 80 million polygons, which at that time was extreme- ly ridiculous, but we were trying to think about the problem in a diff erent way. at forced us to redo the way we thought about the whole pipeline, which has led to an architecture that has lasted for years. Second, we believed we had to fi nd a solution to motion blur. And the third goal was to come up with control over shad- ing and lighting so it didn't have to be done by programmers. How did you solve motion blur? We were trying diff erent things. I had an analytic solution for the problem, trying to come up with an exact solution. But, Rodney Stock suggested that we look at dithering. at triggered Rob Cook to experiment. And he came up with stochastic sampling. e stochastic sampling not only solved the motion blur, but it also opened up solutions to depth of fi eld. So it was a very beautiful and elegant solution to the problem. And then Rob came up with the notion of shade trees for solving the problem of complex shading. You were at Lucasfi lm then? Yes. e architecture was originally called REYES, which Loren [Carpenter] named; it means renders everything you ever saw. When we spun out and became Pixar, the technology, of course, followed us. I think it was [Silicon Graphics CEO] Jim Clark who suggested coming up with a standard way to talk to rendering. It was at that time we initiated an eff ort to come up with an inter- What was the original goal for Render- We wanted to do something that was going to last for many years, so we had, let's say, three main goals. One of them was to think about extreme complexity. We set a goal of being able to manage 80 million polygons, which at that time was extreme- ly ridiculous, but we were trying to think about the problem in a diff erent way. at forced us to redo the way we thought about the whole pipeline, which has led to an architecture that has lasted for years. Second, we believed we blur. And the third goal was to come up with control over shad- ing and lighting so it didn't have to How did you solve motion blur? We were trying diff erent things. Ed Catmull, CG pioneer and president of Disney Animation and Pixar Animation ■ ■ ■ ■ Trends & Technology February 2009 38

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