This story first appeared in the April 10 issue of The Hollywood Reporter magazine.

No actor is indispensable. That is the blunt lesson from the fact that Universal Pictures was able to complete its April 3 tentpole, Furious 7, following star Paul Walker's death in a November 2013 car accident about halfway through the shoot. Beyond saying that brothers Cody and Caleb stood in for Walker and that director James Wan culled footage of Walker from the earlier films, Universal declines to discuss which tricks were employed to breathe life into Walker's character. But sources say Peter Jackson's Weta Digital was asked to complete the sensitive and arduous task of reanimating Walker for Furious 7, and its cutting-edge work points toward a future where most actors can be re-created seam­lessly if needed. (The company declined to com­ment on its specific contributions.)

Read more Vin Diesel Gets Choked Up During Paul Walker Tribute at 'Furious 7' Screening: "It's for My Brother" (Video)

For years, filmmakers have developed increasingly sophisticated techniques for replacing missing actors. Robin Shenfield, CEO of London-headquartered The Mill, which led the Oscar-winning visual effects on 2000's Gladiator, explains how that film coped when Oliver Reed suffered a fatal heart attack during filming. Footage from outtakes was used to create a digital mask that was added to shots of a body double. "He also had dialogue, so we changed his mouth movement," says Shenfield. Producers of HBO's The Sopranos faced a similar issue in 2000 with the passing of Nancy Marchand, who played Tony Soprano's mother. "Basically it was 2D compositing," recalls Rick Wagonheim, who executive produced those effects. "The problem was some of the angles didn't really match as well as they could have."

Cody (left) and Caleb Walker stood in for their late brother Paul on 'Furious 7.'

Today, it's possible to create an actor entirely from digital composites. The Mill, for example, has completed a 90-second Johnny Walker ad featuring a CG Bruce Lee for agency BBH in China. "We created his entire face in CG and hand-animated that, using shots of the actor for reference," says Shenfield. He believes that a CG actor is an option, as long as artists can create his face convincingly. "The eyes require a lot of work," he says. "Keeping motion continuous in the musculature and the eyes is the key to making it look real."

Read more SXSW: Paul Walker Looms Large Over 'Furious 7' Premiere

Some movies now even create 3D scans of actors as production begins, so that they can make CG doubles for complicated stunt scenes. It's not known if that occurred on Furious 7, but it was done on Captain America: The Winter Soldier. Explains VFX supervisor Scott Squires: "If there's any inkling that you might need a scan, they scan the actor at the start of production. I've also heard of certain studios having actors scanned just as an archival thing." That way, 20 years from now, filmmakers would still have access to the likeness of that actor — dead or alive.