Director Jon Favreau Reveals the Secrets Behind the Making of ‘The Jungle Book’

— -- A breathtaking jungle! Talking animals! Even a jaw-dropping gigantopithecus! Ever wonder how the magic of movies like “The Jungle Book” all comes together? Director Jon Favreau told ABC News it’s a fun but challenging process.

"Most of our sets were about the size of what we're sitting in now with one human character, who'd never acted before. So there's a lot of ways it could have gone wrong,” Favreau said. But working with computer animals may have helped simplify the process.

"There are definitely advantages to computer generated animals. First of all, it's a lot more humane,” said Favreau. “Second of all, they can talk. Third of all, they take direction well. And they don't eat you if they get off the chain. So it really was a no brainer."

Favreau, 49, told Peter Travers the animation process was key to making some aspects of the animal’s eyes and mouths seem so real.

"Some of it is the animators. Some of it's the technology associated with Ray tracing, which is a new way of rendering the way light interacts with the subject," Favreau said. “But honestly, a lot of it comes from the director not asking these artists to make those animals do more than they should. In this case we tasked our artists with not allowing the animals to do things they couldn't normally do. By creating parameters and limitations, it actually adds to the beauty and believability of the film.”

Remarkably, Favreau chose only one live actor to appear in the film.

“We wanted to find the right kid. And when you're dealing with a 10-year-old there's not a lot of kids with a lot of experience. And sometimes they have a background from theater that might be a different kind of set of skills or from television,” said Favreau. “But from kid to kid it varies. But the big thing is that you want to find somebody who's got a charisma, a magnetic quality, somebody that you like to watch. And there were 2,000 submissions all around the world. And we found a kid right here in Manhattan who had never acted before who went on tape because his dance instructor gave him a flyer. He was so full of confidence and poise. I kept watching the tape and smiling."

And so began the acting career of Neel Sethi. Favreau opted to work with Sethi, who plays Mowgli, in studio before having him interact with veteran actors Bill Murray, Christopher Walken, Idris Elba and Scarlett Johansson, who all voiced characters in the film.

“The idea that I had for this was to get the Jim Henson Studios to design puppets and the puppeteers to come because they improvise, it’s spontaneous. And if you’ve ever seen a kid interacting with a puppet their eyes light up,” said Favreau. “So whatever it took to get the sparkle in the eye of the performer that comes from them being engaged, you need to hold their interest, otherwise they get bored.”

Favreau noted that when Sethi was eventually paired with the other actors like Bill Murray, they clicked.

“They were out there playing football. I was cooking dinner. The next thing you know, they were in there improvising back and forth. And what I'd hoped would happen, happened,” said Favreau. “And I think some of that spark of spontaneity and honesty came through the film.”

"The Jungle Book" hits theaters today. Disney is the parent company of ABC News.