See How 'Rogue One' Brought Grand Moff Tarkin and Princess Leia to Life

As most Star Wars fans now know, the biggest surprises found in Rogue One are the digitally altered characters of Peter Cushing’s Grand Moff Tarkin and Carrie Fisher’s much younger Princess Leia. Debates about the ethics of such techno-wizardry continue — namely, is resurrecting a deceased actor for a wholly new performance cool or more than a little disturbing? Nonetheless, there’s no denying that the CGI necessitated by such a task is amazing. And in a new ABC News video (above), fans can now get a detailed idea of how Lucasfilm and Disney pulled off this groundbreaking feat.

In the Nightline video, viewers are taken into Industrial Light & Magic’s San Francisco headquarters, where chief creative officer John Knoll explains the reasons that both characters were needed by the film, which takes place directly before — and segues seamlessly into — 1977’s original Star Wars. The specific process required to bring Cushing (who died in 1994) back to the screen involved a combination of binge-watching his Star Wars performance, employing stand-in actor Guy Henry on the set (decked out in headgear that helps record his every facial and vocal movement), and tons of frame-by-frame postproduction tweaks aimed at making Tarkin seem as natural as possible. An older face mold of Cushing, created for 1984’s Top Secret!, helped aid ILM’s digital endeavor.

In response to some critics’ objections to this trickery, Knoll states that he’s comfortable with Rogue One’s signature effect because Cushing’s resurrection was done with “great affection and care.” And as for Leia? Knoll says her brief final scene was done with Fisher’s participation and blessing, long before her untimely passing on Dec. 27.

To hear more from Lucasfilm about this technological movie magic, and to get numerous exclusive behind-the-scenes shots from the production of Rogue One, check out Nightline’s entire video above.

Related: How the ‘Rogue One’ Ending Leads Us Right Into ‘Star Wars: Episode IV’ (Spoilers!)