To get to the fountain of youth, apparently, you need a specially-designed helmet and more than 100 dots on your face. That is how a leading special effects company created Clu, the digital villain who appears as a 35-year-old Jeff Bridges in Tron: Legacy.
Artists at Digital Domain, an L.A.-based digital production studio made Brad Pitt a digital octogenarian for The Curious Case of Benjamin Button. And while the special effects industry saw that as an almost insurmountable challenge at the time, it was nothing compared to the pressure of taking a well known actor and making him look young again, since many audience members know what Bridges looked like in his 30s.
"We realized how much harder now doing somebody people have seen before is. No one had seen Brad at 85, so there was some leeway," says Digital Domain's Steve Preeg, the visual effects supervisor for Tron: Legacy.
So how do you take a 61-year-old actor and make a computerized version of him at 35?
To start with, Digital Domain took a cast of Bridges' head and pictures of his various facial expressions to create a 3-D database of all the things his face can do. How does he smile? How does he frown? What does he look like with one eyebrow raised? Then, Bridges would act out his scenes wearing a specially-created carbon-fibre helmet moulded to fit his head equipped with four small cameras attached to it pointed at his mug. More than 140 dots were painted on his face to allow digital animators to analyze what his face was doing in the scene.
"The reason we use four cameras is because any one dot can always be seen by at least two cameras, so we can triangulate and get a true 3-D position of those dots," Preeg says.
A body double would study Bridges performance and then mimic it for the final footage. With information gleaned from all the dots on Bridges' face, the body double's head would be chopped off in a computer and replaced with a digital version of a youthful Bridges.
It is a time-consuming process that requires a lot of fine-tuning, Preeg says.
"How do you really differentiate in a computer if your smile is sarcastic or happy? It could be something as subtle as a tiny movement in the eyelids," he says.
The entire process took 27 months, including research and development, time spent on the principal shoot and 68 weeks of post-production to ensure that the character looked believable to audiences.
"A creature or a dinosaur, those kind of things, there's a certain level of error you can have in the system and not pull people out of the movie," Preeg says.
Clu may not be perfect, but the technology has made huge leaps since the effects team was tasked with aging Pitt in 2008.
Making younger, digital versions of actors may be in its infancy, but it has been done prior to Tron: Legacy. A digitally created young Arnold Schwarzenegger appeared briefly in Terminator Salvation last year. And though it didn't involve changing the actor's age, the Winklevoss twins were played by one actor who was doubled digitally in this year's The Social Network.
Digitally created youthful versions of actors may just be the future of filmmaking, Preeg says.
"Certainly I would imagine it's going to get better and certainly I would imagine it's going to get more refined and more believable," he says. "It's a movement that I think would open up a lot of opportunity for both actors and directors. It's just going to take time and energy to continue honing the process."
Of course, time isn't the only challenge.
"The thing we're fighting is that the audience is just getting so sophisticated," Preeg says. "A six-year-old girl can just be like, 'Yeah, I can see those effects. Those are bogus.' It's amazing how observant and on top of things the modern audience is."