My second film working with (the awesome) Martin Hill as vfx sup. The two main challenges in this project were the silver samurai, and the Yashida rapid de-aging/aging. I was on the lighting and rendering team.
The hardest part about the Samurai was making him look clean, shiny, and real. He was supposed to be made out of Adamantium ('indestructible' metal) so the client didn't want many scratches or dirt on him. I think we achieved 'cool' but not quite as realistic as I would have liked.
We had to artificially de-age, and then re-age Yashida, the guy driving the silver samurai. This required creating a digi-double of both the young and old actors, as well as a middle variant. We then blended between these and rendered them.
Many features like wrinkles, hair, and skin texture used animated maps to progressively push the transition forward in a more non-linear and organic way. Compositing played an important part in making these maps, and integrating the renders into the plate.
All finished I think it came out well and does a great job at telling the story. This kind of effect I think would have been hard to do practically as a lot of the transitions happened during the shots, not so much across them.
Twentieth Century Fox