Carl and Russell find themselves lost in the wilderness in search of Paradise Falls. This shot progression exemplifies the level of detail and texture and lighting needed to make the jungle seem believable.

Docter concurs that the balloons offered a great opportunity along with clouds and lighting and color. "When we started, we had done rigid body simulations with a smaller number of objects, but the scale of what we wanted -- 10,000-20,000 balloons -- was something we couldn't quite handle up to that point. So we made it more robust. We also spent a great deal of time working on clouds for when Carl sails up into the sky, and when there's the storm later on. There were a lot of clouds at the end that we wanted to move around and get a sense of volume and yet not be solid. We didn't want to mimic real clouds, so we looked at a lot of stop-motion films and The Adventures of Baron Munchausen, where they have this stylized, cotton ball approach to clouds. In the film, we have a combination of clouds that are painted and volumetric that the effects guys generated. It's basically a bunch of spheres or blobs, and then a shader is applied so they look the way we wanted.

"As we set design rules for lighting, we decided to make it a little more theatrical. We had a number of things working in our favor: for the jungle, there is such an incredible complexity to the foliage, that you could pretty much do whatever you wanted in terms of light hitting the character or not. We could put up blockers or cookies that could simulate foliage but be able to steer it where we wanted. I was also a fan of vignetting so the corners of the frame get darker with a brighter spot in the middle. We really tried to use color and saturation for emotional effect. As Carl is alone as his wife passes away, we desaturated the color and made it almost black-and-white. And as life starts to come back through the other characters, and Carl reconnects, we push the saturation up."

Then again, it always comes back to "story, story, story" at Pixar. And Up certainly posed some very difficult dramatic challenges. The opening nine-minute montage setting up Carl's life with Ellie, for example, is a bravura set piece that should be studied in great detail for its structural and emotional execution.

"Bob [Peterson, the co-director] and I -- but mostly Bob -- were able to put together a pitch that was able to move people to tears verbally with no visuals. But then Ronnie Del Carmen started boarding it and took it to a whole other level. We had a series of scenes strung together and we needed to get through this pretty quickly because the story doesn't start until Russell comes in. So we have to compact his life. It was a process of whittling down. We stayed away from narration and stripped away dialogue. We made it more like a Super 8 film that I remember my parents making when I was a kid, and there's something emotional about not having dialogue and sound that makes you an active participant."

Scott confirms that the montage grabbed him immediately as a pitch and enjoyed animating because of its pantomime quality and emotional daring. "It almost feels liked its own short film. How about giving an audience an emotion other than just throwing jokes at them for 85 minutes? I interviewed Chuck Jones once and he talked about the relationship between comedy and tragedy. He mentioned all the plays he read and watching Chaplin. The funny things in Up are funnier because of the tragic things that happened."

The opening montage depicting Carl and Ellie's married life was the pitch that set Up in motion. As a result, the humor is "funnier because of the tragic things that happened."

As for the strong paternal link with Monsters, Inc., Docter says that was a happy accident. The theme of fatherhood evolved as we got into the story. And, really, even before we involved Russell, we started to play with this idea that Carl never had a chance to be a father in his life with Ellie. And in an earlier version, Kevin, the bird, had an egg that Carl had to care for. And that's how he got wrapped up in what seemed to be a distraction away from his goal of getting his house to the falls. But then when we brought in Russell, it seemed like a great idea to handshake both ways, where [each fills a void]."

But Docter returns to the montage in summing up: "The opening about married life is one of my favorite moments. It was a chance to be cinematic and really tell the story visually. I'm really proud because there was a lot of nervousness about the level of stylization and caricature that we were taking with the story, and especially nervousness that we might lose the emotional connection by taking it to an extreme. But it seems to be really affecting people and that's really cool."

Bill Desowitz is senior editor of AWN and VFXWorld.