Check out Up in The 2010 AWN Oscar Showcase!

There's a reason why Up shines brightly and contains such rich shadow detail. That's because Pete Docter's Pixar film had the benefit of point-based rendering for ambient occlusion and indirect illumination. Much faster than previous ray-traced methods, this evolutionary computer graphics technique has enabled color bleeding effects and realistic shadows for complex scenes.

In fact, this point-based method for computing diffuse global illumination (color bleeding) is much faster and uses less memory than ray-traced methods. Its developers -- Michael Bunnell, Christophe Hery and Per Christensen -- will be honored with a plaque by the Academy of Motion Picture Arts and Sciences at the annual Scientific and Technical Awards presentation at The Beverly Wilshire.

An interesting irony, though: This started out as a realtime GPU technique at NVIDIA and ended up as an offline rendering CPU technique and now is a standard feature of Pixar's RenderMan.

"I was working on the shader/compiler team at NVIDIA," recounts Bunnell, who is now founder of Fantasy Lab, an indie game developer in the San Francisco Bay area. "Anyway, somebody in the demo group read an ILM paper on ambient occlusion and implemented that into one of their demos and they asked me, because I had done the tessellation code in the smooth surface, if they could evaluate the ambient occlusion value -- the shadow or the darkening effect -- and they wanted me to change my tessellation routine. They did the 'Dancing Ogre' demo, rendered in realtime. There was no problem using the ILM technique because it was pre-calculated. And so they would bake in the ambient occlusion for each position of all the characters for every frame and that ran over night. And when the more programmable graphics chips came out, especially when they had the ability to do branching and looping, I decided to investigate a method to calculate the ambient occlusion on the fly. It was one of the chapters I wrote for the GPU Gems book. Once I got the idea of working with a point cloud, I came up with the idea of making it hierarchical, which was the main thing that Pixar picked up on and liked.

"Well, if you throw away the geometry and ignore the form factors, then you get the shadow and it gets to be too dark in places. But I found an indirect way of calculating visibility. And I also realized that I could use this as more of a general transport system, so I could use it to do indirect lighting or large area lights. So instead of trying to solve the entire global illumination problem, I was able to solve the problem that we have no solution for."