Lucasfilm Digitally Scans All Their Actors’ Faces
Rogue One’s Grand Moff Tarkin was an awkward cast member for a few reasons. Even if viewers didn’t know Peter Cushing was long dead, anyone could tell that Tarkin was a digital recreation and not the real thing. Fans were also uncomfortable with the idea of resurrecting actors in pixels, and because of the backlash, it doesn’t seem likely that the Star Wars series will attempt anything like that again (they’ve already promised not to do so with Carrie Fisher). But that hasn’t stopped them from digitally scanning all their lead actors’ faces just in case.
We will always [digitally] scan all the lead actors in the film. We don’t know if we’re going to need them. We don’t intentionally scan them as an archive process. It’s for reference later.
In The Last Jedi, there’s a memorable scene near the beginning where General Leia is blown out of her ship and into the vacuum of space, and uses the Force to carry herself to safety. The Last Jedi’s digital animator Stephen Alpin explained that actually shooting that scene with Leia on wires would have been “cost prohibitive,” which is why they went with a digital composite:
You don’t just have the range of freedom that you actually get with CG. If we can shoot it in-camera, let’s shoot it in-camera. If there’s a certain aspect to it, let’s shoot it, and then we can match to it. We had Rian [Johnson’s] shot of Carrie doing the scene. That was for us to be able to add some of the idea that she’s freezing over, as she’s in that vacuum of space, meant that we had to do CG work and re-project her onto a CG version of the character. We kept her performance pretty much intact and were matching, where needed, with any animation stuff. It was pretty much all Carrie.
That sequence was shot in three layers, one with Fisher’s performance, one with a few stunt performers layered onto each other, and one with a digital recreation of Fisher’s face. Presumably, they scan the other actors’ faces just in case there’s a scene it would just be easier to do digitally rather than put the actors in danger.
They don’t mention this in the interview, but I suspect much of it is for fight scenes, where people are doing lots of acrobatics and they might want to layer in a stunt performer for one shot, but replace their face with the face of the actor in the scene. That’s how I, Tonya accomplished a lot of the ice skating jumps — Margot Robbie learned how to skate and turn, but the jumps were done by real, professional skaters, and her face was digitally added later.