'Terminator: Genisys:' A CG Schwarzenegger Is the Latest in Hollywood's Work Toward Digital Humans

Terminator: Genisys Split - H 2015
Paramount Pictures

Terminator: Genisys Split - H 2015

[Warning: The following story contains spoilers about Terminator: Genisys.]

After three decades, the young Arnold Schwarzenegger that appeared in James Cameron's 1984 The Terminator is back in Paramount's Terminator: Genisys — but this time, he's fully computer generated. This CG double was used in several sequences in the new film including a shot-by-shot re-creation of the iconic scene from the original Terminator in which the T-800 cyborg arrives from the year 2029, landing near Los Angeles' Griffith Observatory.

The CG Terminator underscores continuing work toward creating the "holy grail" of visual effects: A digital human.

While not a new topic, the difficult task of re-creating a human in the computer has generated a flurry of new attention this year, due in large part to the use of digital technology to complete Furious 7 after actor Paul Walker died in an accident prior to completion of production, along with a move to create digital likenesses of entertainers such as Buddy Holly for holographic-like live entertainment.

The specific challenge of creating a CG Schwarzenegger was handed to Technicolor-owned visual effects house MPC.

"I pretty much thought this was an absolutely insane task," says MPC VFX supervisor Sheldon Stopsack, describing how he reacted when first given the assignment. "Digital humans are considered the holy grail in VFX, and then combining that task with such an iconic figure was probably increasing the difficulty by a hundred if not a thousand. [But there was also] a fascination and something appealing to it."

MPC, which recently worked on Cinderella and X-Men: Days of Future Past among other projects, knew it had to step up its game. "The young Arnold [as he looked in 1984] doesn't exist anymore; he has aged," Stopsack says, explaining that they therefore ruled out approaches such as a cyber scan or shooting reference photography of the actor.

The key was research, lots and lots of research. "We started to research what Arnold looked like (and moved like) in 1984; we tried to get our hands on every single piece of footage that we could, [as well as] photography and books. Luckily he was such as iconic figure that he was well documented." A key reference was also the 1977 bodybuilding documentary Pumping Iron, which featured Schwarzenegger.

Referencing their research, MPC then started to model the character in the computer. "We were also lucky enough to receive a cast that was taken of him in 1984, which was a great starting point, but it didn't have the detail of a cyber scan that you could get these days," Stopsack says.

For the facial animation, they did performance capture using SciTech Award-winning system Mova. "Arnold Schwarzenegger made himself available for a performance-capture session. He performed the lines," Stopsack explains.

But he adds that for facial expressions or fight shots, performance capture from the actor today probably would not have been anatomically accurate. "His appearance has changed, obviously," he said. "We set up a library of individual expressions and body movements [based on the research] and associated these with each individual shot. So body movement was hand-animated; performance capture was really only used for the dialog.

"We had a stunt double, Brett Azar, as a stand-in to help with the choreography in the principal photography, and we replaced him with a CG version of young Arnold," Stopsack says.

Another challenge to making the time-traveling adventure was that this time around, there's the young Terminator, a middle-aged Terminator and an older Terminator. Schwarzenegger played the two older versions of the character (except in shots where a CG stunt double was required).

There's even a sequence during which the young and middle-aged versions of the character come face to face and fight each other.

"For the majority of the shots in that scene, Schwarzenegger was fighting the stunt double," Stopsack explained. "There were also a few shots where we had two stunt doubles fighting each other for more action-heavy and more dangerous shots. For those we used face replacement for the older Arnold, which was partly done by MPC and partly by Lola VFX [which focuses on the sort of digital cosmetics used, for instance, on the CG Brad Pitt in The Curious Case of Benjamin Button.]"

It's often said that creating active eyes is among the most difficult aspects of work on a CG human. Was it therefore an advantage that the T-800 is a cyborg? "We thought it would be, but the reality is it wasn't," Stopsack says. "As robotic as his character was, there were a lot of subtleties that made Arnold's performance. [We had to] create it like a human acting like a machine.

"Eyes are a huge part of it," he continues. "At the same time, every other subtlety of the face becomes equally important. If you don't have enough detail in the mouth area or the lips or twitches, the whole character falls apart. … It came down to making sure the subtleties [were there] in all parts of the face and body. If anything was falling behind it was noticeable almost immediately and the character wouldn't be believable anymore."

With growing uses, including in the aforementioned Furious 7, there's been discussions about when it's appropriate to create a CG human. Stopsack addressed this question in broad terms, saying, "It's a tool for filmmaking. From a production standpoint, you have to consider what's the benefit and what you hope to get out of it.

"In the case of Terminator, it was an integral part of telling the story, which was about time travel and two characters facing off from different times. Because it's so difficult to create a digital human, there's got to be a good reason to do it. Otherwise [it should be] the actor."