The big breakthrough in Shrek the Third is global illumination. With GI, every detail in the architecture connects things together and provides richness. All Shrek the Third images © & ™ DreamWorks Animation Llc.

Sonny and Cher once sang that "the cars keep on going faster all the time," but were their duo still around today they might be talking about advances in CG software. The computer animation studios are playing "can you top this" with proprietary stand-alone and plug-in programs that keep narrowing the gap between pixels and real life. Even with (or because of) ever more powerful computers, the need for software that can cut corners and ride herd on huge amounts of data is greater than ever before.

None of the summer's big three animated features is attempting to create a hyper-real world for itself; the goal of their technological window-pushing is to make their imaginary internal worlds as real as possible on their own terms.

DreamWorks Animation: Shrek the Third
"We try to make each film look better than the last," says Philippe Gluckman, visual effects supervisor on DreamWorks' Shrek the Third. "Even though the Shrek world isn't hyper-realistic, there's a certain degree of realism."

For Gluckman, the big breakthrough in Shrek's latest adventure is in global illumination. In real life, light bounces around from one object to another. Photographers use this to their advantage and put bounce cards around the model to illuminate it.

"The computer lighting models didn't know how to do this -- it's very complex behavior. We began prototyping an affordable solution on Shrek 2 so we could get the nice behavior without spending 24 hours on every frame. There have been global illumination algorithms in the past, which looked great but were completely unaffordable. It's very complex to shoot all these rays of light and calculate how they bounce around. The initial attempts were completely impractical, so we developed our own solution and used it with great success -- we all fell in love with the results. It's possible to do it by hand, but it takes a long time for lighter to emulate all the subtleties that you get in that kind of behavior; they'd have to put in 50 lights to get the same complexity."

The clothing in Shrek the Third made a great leap forward also. Now characters can have flowing cloth that drapes and behaves realistically. Shrek and Fiona even wore several layers of clothing that were animated together.

Gluckman points to a scene in Shrek the Third where Fiona and her princess pals are running through the castle. "One shot I remember is when they run under those archways. The whole environment is basically lit with global illumination. Architecture is difficult in the sense there's a lot of flat panes and they'll have a tendency to go a little dead if there isn't enough detail in there. With GI, every detail in the architecture connects things together: the objects illuminate one another and provide a lot of richness.

"Another place that comes to mind is towards the end of the movie when Shrek is in chains and fights the prince. That was lit way more simply than we used to, just using the one light and getting all the bounces out of it. In that particular case, it gave us very dramatic lighting: it definitely supported the mood we were trying to establish. What's interesting about it is even though it's a physical behavior and you get something pretty realistic, we still have tools on top of that for all the usual art directing we like to do. We often make decisions on purpose to get away from reality. In GI, when a character is next to a red wall, you're going to get a lot of red light bouncing onto that character; you still want the lighter to be able to manipulate the image in case the red concentration is too high."