The special effects in Alita: Battle Angel as produced by Weta Digital are the final frontier of motion-capture technology as we know it. They won’t stay that way for long, of course: When James Cameron's first Avatar sequel premieres, it will surely feature even newer techniques. But for the moment, the technology employed to create a 3D version of Yukito Kishiro’s 1990 Gunnm manga is the most seamless use of MOCAP you’ve ever seen – and you’ve seen a lot.
Believe it or not, motion capture is actually more than a century old; the term itself simply refers to capturing human motion and translating that motion to a different medium. One of the earliest uses of motion capture is a cartoon animated using rotoscope. In 1915, animator Max Fleischer developed the technique of tracing over frames of live-action human footage, giving the cartoons less-jerky movements. The technique is still in pretty wide use today – Richard Linklater’s A Scanner Darkly and, most recently, Adult Swim’s Dream Corp, LLC were produced with Rotoscope, to stunning results. But still, things have come a long way.
The animated performances most mainstream audiences think of when it comes to motion capture may be Jar Jar Binks in the Star Wars prequels, Gollum in The Lord of the Rings and the Hulk in the Marvel Cinematic Universe. Until the mid-2000s, the process involved an actor wearing a motion-capture suit (catsuit, ping-pong balls; you’ve seen them) and a camera literally capturing the action that would eventually be laid over with animation. And then there was Avatar.
Speaking to CBR at a recent press event for Alita: Battle Angel, producer Jon Landau detailed what Avatar did that changed the game so completely, and how the team at Weta used Alita: Battle Angel to press even further.
“I’m gonna go back even before that when Bob Zemeckis started doing his movies with motion capture," he said. "We looked at the landscape when we were doing Avatar and felt that motion capture was missing one very key letter in front of it – an 'e' for 'emotion capture.' Two of the films Landau refers to are Beowulf and The Polar Express, both of which were groundbreaking in their use of motion capture on actors like Tom Hanks and Ray Winstone, but were poorly received, perhaps in part because motion capture was still missing the mark on recreating humanity.
“[The emotion] is what we wanted to bring out,” Landau continued. “So we added to the process with Avatar a single-camera head rig that would capture [a face] while you’re capturing the body. That changed it to ‘performance capture.’ But that was a single-camera, standard-definition mode. With Alita we went to two high definition cameras that tracked every little nuance that she did.”
That meant that literally every single one of Rosa Salazar’s body movements and facial expressions was captured on two high-definition cameras. "We analyzed that with Weta, frame by frame almost pore by pore," Landau said, "and then Weta was able to build a model that in a single eye had more geometry and more definition than all of Gollum in Lord of the Rings.”
Interestingly, as intense as that sounds, actually performing with motion capture isn’t as high-impact as one would expect. All that’s required of the actor is to work in a catsuit and a small head camera. Better than a corset, if you’re in a period piece. According to actor Ed Skrein, whose character, along with Jackie Earle Haley’s, is almost entirely rendered by motion capture, the experience was actually liberating – specifically when it came to the lack of costuming involved.
“[It was] very similar to normal performing," Skrein told CBR. "You know the motivation for each scene, the fuel for each scene is internal, so no MOCAP can change that. But it was quite liberating, actually, was the thing that surprised me is like, it felt quite free… just to be a blank canvas and it’s all about the internal. I really enjoyed that and it’s something that I would definitely like to do again.”
Looking at the detail in Alita's iris makes us wonder just what Cameron's going to be able to render in future Avatar sequels that promise to advance the precision of MOCAP even further. Alita: Battle Angel might be the first unofficial trailer for Cameron's soon-to-be-continued franchise.
Directed by Robert Rodriguez, Alita: Battle Angel stars Rosa Salazar, Christoph Waltz, Jennifer Connelly, Mahershala Ali, Ed Skrein, Jackie Earle Haley, Keean Johnson, Michelle Rodriguez, Lana Condor and Eiza González. The film is in theaters now.