Virtual characters have been used when an actor dies in the middle of a film production, as when Universal Pictures combined CGI and previous footage for Paul Walker's role in 2015's "Furious 7" after Walker's 2013 death in a car crash.

But "Rogue One" broke new ground by giving a significant supporting role to a dead star. A digital embodiment of British actor Peter Cushing, who died in 1994, reprised his role from the original 1997 "Star Wars" film as Tarkin.

Walt Disney Co recreated Tarkin with a mix of visual effects and a different actor.

A Disney spokeswoman declined to comment on whether Princess Leia would appear in films beyond "Episode VIII," set for release in 2017. Fisher had wrapped filming for the next "Star Wars" episode before she died. She suffered a heart attack on a flight from London to Los Angeles.

Fisher had been expected to play a key role in the ninth installment of the sci-fi saga, due for release in 2019.

Fisher's attorney, Frederick Bimbler, did not return requests for information on any stipulations the actress may have made about use of her image.

The rights of actors' heirs are rooted in a 1985 California law requiring filmmakers to obtain permission from a celebrity's estate to use his or her image after death. The law was enacted after a campaign by the son of Dracula actor Bela Lugosi, a lawyer who objected to widespread use of his late father's image.

With today's movie technology opening up so many possible scenarios, actors' union SAG-AFTRA is lobbying for all states to enact protections on the use of celebrity images after they die

My own impressions from having seen this technology is that it is a work in progress. I'm reminded of the "dinosaurs" from Jurassic Park. They're not really dinosaurs, they are really modern amphibians with some dino DNA added. The synthespians used in Rogue One are not Peter Cushing and Carrie Fisher; they are other actors with some of the "DNA" of the original actors. My two cents.

I should mention the synthesipian idea, which was used in William Gibson's Idoru. The word was coined by Jeff Kleiser. Kleiser and Diana Walczak created the first digital actor for their 1988 short film Nestor Sextone for President.

However, the first reference to the idea of a computer-generated person occurred in Robert Heinlein's 1966 novel The Moon is a Harsh Mistress. The computer created the person Adam Selene:

"...what's to keep me from showing face, Man? I'm showing a voice this instant... I can show a face the same way."

Was so taken aback I didn't answer... I said, "No, Mike."

"Why not, Man?"

"Because you can't!. Voice you handle beautifully. Involves only a few thousand decisions a second, a slow crawl to you. But to build up a video picture would require, say, ten million decisions every second. Mike, you're so fast I can't even think about it. But you aren't that fast."

Mike said softly, "Want to bet, Man?"

...We waited in silence. Then screen showed neutral gray with a hint of scan lines. Went black again, then a faint light filled middle and congealed into cloudy areas light and dark, ellipsoid. Not a face, but suggestion of face that one sees in cloud patterns...

It cleared a little and reminded me of pictures alleged to be ectoplasm. A ghost of a face.

Suddenly firmed and we saw "Adam Selene."

Was a still picture of a mature man. No background, just a face as if trimmed out of a print...

Then he smiled, moving lips and jaw and touching tongue to lips, a quick gesture...