The first thing I saw when I walked into the room was — of course — a bunch of beautiful helium balloons. And then I saw Pete Docter, the lanky and affable director of Pixar’s new film, “Up,” about an extraordinary journey to South America in a house lifted into the sky by an enormous bunch of balloons.

What makes a good voice actor for an animated film?

Some actors can create a picture of what is happening with their voice. Some actors works a lot with their bodies and facial expressions. You have to unplug the video part and listen to the voice. For Carl we wanted a voice that was grouchy and curmudgeonly, a voice that suggests that nothing is quite as good as it used to be, but a voice that is still very appealing and funny and Ed Asner fit that bill. You can tell he deeply cares about the peoople he is insulting. For Russell Joe Grant taught me to ask, “What are you giving the audience to take home?” You have to have some relatable emotion as a foundation for the fun stuff. You need the sad beginning so that you care about Carl and want what he wants.

What movies did you love as a kid?

I loved “Dumbo.” I watched Bugs Bunny time and again. The Muppets were big, too. All of those, they have this real, not darkness but poignancy, that’s what makes it stick with you. We tried for that in this film. When we were about halfway done we showed it to an audience, and the highest group of positives was women age 12-25 because they connected to the story.

Did you draw inspiration from real-life locations for some of the stunning images in this film?

Yes, we studied the Tabletop Mountains called tepui, with all these weird rock shapes. You start to see figures in the mist. There are strange plants you dont see anywhere else. It is where Venezuela meets Brazil and Guyana. “The Lost World” was inspired by this one mountain we studied. Most of them have never been set foot on. The more we can base on real life, the more you will believe the stuff we make up. The bird in the film was based on a crane and a monal pheasant, the most iridescent creature there is.

Every animated movie director tells me there was one technical challenge that was especially difficult. What was yours?

Balloons! The maximum our system could only handle was 500 and we had to expand to ten thousands. Not only does each balloon “know” where the others are, each one can respond to wind, turbulence, and each of the other balloons. And we could not have thousand strings. The whole things is so preposterous we had to find little elements that anchor it and make it more believable but also poetic.

What were some of the decisions you made about the film that were different because it was being made in 3D?

We did a bunch of reseasrch what makes successful 3D. We did not want the “Whoa! 3D” effects that take you out of the movie; we wanted them coming out of the story. 3D allows us to play with the depth the way we use color and lighting. When Carl is cut off and closed, we made it claustrophobic and slow. When he triumphs we make it as spacious as we can.

I don’t know the exact quote, but there is this thing that Walt Disney said, something like, “We’re not making these movies for kids, we’re not making them for adults; we’re making them for that still quiet part the world has made you forget but that our films can make you remember.”