One of the biggest criticisms that's been leveled at Rogue One: A Star Wars Story has been the decision to bring Peter Cushing's Grand Moff Tarkin back from the grave through the use of motion capture technology.
Cushing, who played the character in the original Star Wars, passed away in 1994 but the producers felt that Tarkin was integral to any story involving the Death Star and had to appear in the film. Rrather than re-cast the character, special effects gurus at Industrial Lights and Magic decided that the technology to re-create Cushing's likeness was available and decided to use it as a nod back to the original film.
The end result has raised many a debate about the ethics involved but there's no denying the decision came out of a place of love for the original film rather than as a cheap money grab.
The below video is a visit to ILM headquarters where the team behind the special effects explained exactly how they achieved the recreations of both Tarkin and a young Princess Leia.