With only one new movie hitting theaters in wide release this weekend, many fans may opt to check out the blockbuster spin-off Rogue One: A Star Wars Story again before it ends its theatrical run. Those who do so will get another chance to see the late Carrie Fisher on the big screen, sort of, as her younger self is recreated digital for a Princess Leia cameo. Today we have new details about how Carrie Fisher was involved in the Rogue One production process, from LucasFilm's John Knoll.

ABC News caught up with John Knoll, chief creative officer and senior visual effects guru for Lucasfilm, who also has a story credit on Rogue One. He confirmed that Carrie Fisher was involved in the production process. He also revealed that she loved being participating in the movie, and enjoyed the final product.

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"She was involved in the process and, you know, she saw the final result and she loved it. She got to see the scene. (Kathleen Kennedy, president of Lucasfilm] showed it to her. So, I got a call afterwards from Kathy saying, 'Well, Carrie loved it.'"

The LucasFilm executive revealed that he was quite nervous about both using Carrie Fisher's iconic Princess Leia, and the CGI version of the long-deceased Peter Cushing as the villainous Grand Moff Tarkin. Despite his reticence to use these characters, which did cause some amount of controversy, the LucasFilm executive spoke about why these additions were necessary. Here's what he had to say below.

"Because of the nature of the film, the way it sort of mates up right to 'Episode IV,' I thought it was important that it sort of end with that Leia moment, where she's handed the plans and then we see where it goes after. For Tarkin, it's because he's such an important part of Episode IV and the Death Star program. And given that this movie is, you know, about the threat of the Death Star, what it represents, and then how the rebellion responds to that threat. I thought it was important that Tarkin be part of this. I think it's a really good match to what she looked like in 'Episode IV.' We had really good scans of her, and, we matched a couple of frames very exactly with our CG model and then sort of bounced back and forth between our render and the archival frame."

Carrie Fisher's Princess Leia and the digital re-creation of Grand Moff Tarkin weren't the only familiar faces Star Wars fans saw. There were also a number of scenes of the iconic Darth Vader, with James Earl Jones returning to voice this iconic villain. Rogue One: A Star Wars Story will try to win its fourth weekend in a row at the box office starting today, as it goes up against Underworld: Blood Wars and expanding movies such as A Monster Calls, Hidden Figures and Lion.