Disney Pixar’s “UP” is out on Blu-ray and DVD! To celebrate we are posting the fifth section of an interview with the co-writers and directors of “UP,” Peter Docter and Bob Peterson. You can check out the fourth section of the interview here.

Q: How was the idea for collars enabling dogs to talk arrived at? How much of it was comedy and how much of it was inspired by fact?

Bob Peterson: We knew we wanted to give Carl a new family including a new “grandson” and “family dog.” It was a gauntlet laid down in front of him to accept new people into his life. Before Russell was invented, we just had Dug along for the journey and it turned out to a pretty quiet journey. So we invented the collars. We love comedy and we knew that the collars would provide plenty of laughs, peering into our beloved canine friends’ brains. But more importantly, Dug is a mentor for Carl in that new relationships are always offered to us, and it is up to us to act on them.

Q: When you release the final film is it like watching your kids go off into the world? You’ve shaped it, guided it along, and then you have to let them go and see how they do.

Bob Peterson: Yes. It is interesting watching the movie for the first time at our wrap parties with our crew. We don’t ever get to see our movies like a regular audience member because we lived through the creation of the film and see the memories brought forward by each shot and movement we see. When I look at my 14-year-old (who I don’t want to grow up and go to college!), I see her as a 3-year-old at the pumpkin patch, the 5th grader at the spelling bee. Those memories are there. When our movies leave us, we hope we’ve given them enough love and sense to do great things in the world!!

Q: Pete and Bob, you’ve both worked as writer, director and even provided some of the voices for a few of the characters in your films. What do you enjoy doing most and why?

Bob Peterson: I have been lucky to have worked in most of the animation spectrum – from purely technical over to purely creative. A new industry like computer animation (now 30 years old or so) allows for that sort of variance in jobs. I love the people I work with, I love writing a funny line and hearing it as a huge laugh in the theater, and I also love leaving my desk and performing in front of a microphone and creating characters. They’re all my favorite.

Q: We saw the video of the trip to gain artistic inspiration for “Up”…what are some examples of other inspirations for animated elements in your work that came from more mundane/conventional sources?

Pete Docter: Doing research is one of the best parts of working on these films. One day we brought in an ostrich. It was cool to see an ostrich running around on the front lawn here. And of course the film was a great excuse to bring in our dogs. We also went to a few retirement homes. We formed a band and played Tin Pan Alley-type tunes and went in to play for them. As we played, we were secretly taking mental notes and doing sketches behind our ukuleles. It was great — we got good research, and they said we were the best act to play there in months!

Q: Was it intentional to have Carl look like he’s made of cubes? If so, why make him so blockish looking? Are all of the characters based on geometric shapes?

Bob Peterson: Absolutely. Rick Nierva who is the production designer is a big fan of creating characters whose shapes give clues to their personalities. A cube is not something that rolls or moves fast – it is very stable – perfect for Carl. A circle can roll and move fast – great for Russell. The more realistic we go with our characters, the less appealing they become because humans have the great ability to discern what is real in a human face and what is not. Basing characters on shapes caricatures them, moves them away from reality, and in a way let’s the audience’s left brain relax so that they can be more involved with the emotional journey of the characters.

Q: Pete, you’ve said in the past that you identify strongly with Buzz Lightyear, are there any other characters you identify with?

Pete Docter: Well, I identify strongly with Carl. I often grouse about how things are changing, and “why did they take that item off the menu?!?” I’m going to make a good old man. Weirdly, Kevin the bird is another character I really like. Not that I feel a kinship, but she was a fun character to play around with, because she’s so unpredictable.

Q: I love the amount of research that’s been put into the look of the mountain tops; were any similar tests conducted into using helium balloons to lift an entire house?

Pete Docter: The first thing our technical team did when they started working on the balloons was to figure out how many balloons it would take to lift a house in real life. Here’s his math: Carl’s house is 1,600 sq ft. He found some figures saying that the average 1,600 sq ft house weighs about 345,000 lbs, of which 160,000 lbs is from the foundation, and about 30,000 lbs is from the garage. Since Carl lifts off and leaves the foundation behind, that leaves about 155,000 lbs, which is 77.5 US tons or 70,306 kg, which the canopy needs to lift. Accelerating toward the ground at 9.8 m/s2, that’s 688,998 N of force from gravity that the canopy has to overcome. With the density of helium at .1786 kg/m3 and representing a balloon as a sphere with a radius of 2.78 ft (like weather balloons), each balloon can generate 4.5 N of buoyant force. To generate at least 688,998 N of force to overcome gravity, you’d need 153,053 helium-filled, 5.56 ft diameter balloons. If you’re trying this with big party balloons, at about one foot diameter, then you’d need a whole lot more: about 26.5 million balloons. None of this takes into account the weight of the balloons themselves or the strings to tie them to the house.

Have you picked up your copy of “UP” on Blu-ray or DVD yet?

Walt Disney Studios Home Entertainment

Related Articles To This Post:

• Interview With “UP” Writers And Directors Part 4
• Interview With “UP” Writers And Directors Part 2
• Interview With “UP” Writers And Directors Part 3
• Interview With “UP” Writers And Directors Part 6
• Interview With “UP” Writers And Directors Part 1
• Disney Pixar “UP” Blu-ray and DVD Review
• UP The Movie New Trailer
• Roundtable with Up’s Ronnie del Carmen
• Up The Movie From Disney and Pixar
• Disney Pixar’s “UP” Was The Top iTunes Movie Of 2009
• Interview With Pixar Research Guide For UP The Movie