How the ‘Gemini Man’ visual effects team created a young Will Smith

Painting in the digital medium of ones and zeroes, today’s visual effects artists can conjure almost any creature imaginable. A flying elephant? Sure. A rampaging 400-foot lizard? You bet. Talking lions? Hakuna matata. For decades, though, one particular creature has remained stubbornly just out of their reach — and, in a cruel twist, it happens to be the one they see in the mirror every day.

In the visual effects community, creating a completely believable, photorealistic digital human being, capable of holding its own alongside flesh-and-blood actors for an entire film, has long been considered the holy grail. Films like “The Curious Case of Benjamin Button,” “Tron: Legacy,” “Star Wars: Rogue One” and “Blade Runner 2049” have moved the industry toward that goal in recent years, with varying degrees of success. Now director Ang Lee is making the boldest — and riskiest — effort yet with the sci-fi action film “Gemini Man,” which pits the 50-year-old Will Smith, as a government hit man, against a 23-year-old version of himself.

For more than two years, Lee and some 500 visual effects artists have been working virtually nonstop to try to pull off a convincing facsimile of one of the world’s biggest movie stars as we haven’t seen him since he first burst on the scene more than 25 years ago. And until the film hits theaters on Oct. 11, they won’t be sure if they have pulled it off.

“From the start, I said, ‘This will be harder than we can imagine,’ ” Lee says. “Every shot is going to be under scrutiny. That’s really scary. I’m still scared.”

The idea for “Gemini Man,” in which aging assassin Henry is hunted by a younger clone who’s able to predict his every move, had been bouncing around Hollywood since the mid-1990s, waiting for the technology to catch up with the concept. In early 2017, producer David Ellison, whose Skydance Media had acquired the project from Disney a year earlier, pitched it to Lee.

Having created a CGI Incredible Hulk for 2003’s “Hulk” and a digital tiger for “Life of Pi,” the director was instantly intrigued both by the film’s technological challenge and its philosophical ramifications. “How a person deals with his younger self, two characters brought up differently but with the same genes — a situation like that just forces you to examine what we’re about,” says Lee, who has won the directing Oscar twice, for “Life of Pi” and “Brokeback Mountain.” “So I got down to figuring out how to do it. It was exciting.”

In recent years, visual effects artists have refined the ability to play God with the aging process in films like “Captain Marvel,” in which Samuel L. Jackson played a more youthful Nick Fury, and the upcoming Martin Scorsese gangster epic “The Irishman,” which will feature Robert De Niro and Al Pacino playing the same characters across three decades.

But because “Gemini Man” often involved Smith playing both characters in the same scene — and because Lee intended to shoot the film in a high-frame-rate format that would be less forgiving of any sleight of hand — the “Gemini Man” team had to employ an entirely different approach from the typical CGI-Botox-style “de-aging.”

“The term ‘de-aging’ usually refers to shooting the actor on set using makeup and then there’s a post-[production] process on top of that to smooth out wrinkles, thin the face, possibly graft in a couple of photographed skin pieces from a double,” says visual effects supervisor Bill Westenhofer, who shared an Oscar for his work on “Life of Pi.” “Whereas we are creating from whole cloth a fully digital human. In our nerdy world, the latter is a lot more difficult.”

To understand that difficulty requires grasping the concept of the “uncanny valley,” a phenomenon identified by a Japanese robotics professor in 1970 to explain why a not-quite-perfect representation of a human is so unnerving.

“There’s so much subtlety in expression; you can tell if someone is mad at you or happy with you,” says Weta visual effects supervisor Guy Williams. “If you create a digital human and you don’t get 100% of that nuance in there, your brain instantly starts to throw red flags saying it can’t quite understand what’s going on. If any one part isn’t right — the eyes, the lips, the shape of the nose, the head angle — the whole thing starts to crumble.”

Before production even began, Williams’ team at Weta began the process of building the clone, dubbed Junior, using for reference images and footage of young Smith from the sitcom “The Fresh Prince of Bel-Air,” which launched in 1990, and films including 1993’s “Six Degrees of Separation” and 1995’s “Bad Boys.” In addition to closely studying Smith’s face and early performing style, they looked at research papers on the aging process to understand subtle physical changes, like how much the nose grows in adulthood. They pored over all the minutiae of the human face: the various types of melanin in the skin and how they interact with light, the different layers of the eyeball, how the lips stick together slightly when the mouth opens, the fine details of tooth enamel.

During production, the film was essentially shot twice, once on an actual set with Smith playing Henry opposite a stand-in for Junior and then a second time on a performance-capture stage, with Smith, wearing a body suit and facial camera, now playing Junior opposite a stand-in for Henry. Weta’s visual effects artists then collected the data captured from that second shoot and brought it together with the work they’d done digitally modeling the younger Smith to flesh out Junior.

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Still, for all the high-tech wizardry brought to bear, the character remains firmly rooted in Smith’s performance. “Will had to get all of the nuances in the difference between his 50-year-old self and his 23-year-old self,” says Westenhofer. “There wasn’t a magical technical button for that part of the equation.” (“I couldn’t have played Junior at 23 years old,” Smith told reporters in July at a presentation of footage from the film. “Now I’m able to understand and capture both characters because of the amount of experience I’ve had as an actor.”)

For everyone involved — from the executives at Paramount Pictures, which is releasing the film, on down — the process of making “Gemini Man” involved a major leap of faith. There was simply no way to know whether this high-wire walk across the uncanny valley would work until it was too late to turn back.

“You could think about it, you could imagine what it may be like, but there was no example in life [to] visualize it,” Lee says. “Your heart is pounding for a year and a half, and then one day you see one of the shots and it’s really exciting. Then you still worry about the other 500 shots. It just takes one shot to take you out of the movie.”

In the end, the visual effects team behind “Gemini Man” hopes Junior will be so thoroughly convincing that the audience won’t have any sense of the endless hours of work and anxiety that went into bringing him to life.

“Our ultimate goal is to work ourselves out of recognition,” Westenhofer says. “If someone watches the film and says, ‘Will did a great job in that performance, and they did a nice job smoothing out his wrinkles,’ we’ll have pulled it off.”