Joe Letteri, Director of Weta Digital, recently gave a presentation on the special effects used in The Hobbit: An Unexpected Journey. Weta have now released a video of the special effects and, together, these give a real insight into this side of the film, as shown in Collider . Here is the video and some of the information from Joe Letteri’s talk.
Two interior sets were built: one to the scale of Bilbo and the Dwarves (ie normal) and one to show Gandalf in a cramped and confined space; the former set was dressed with the homey interior of the film, while the latter was fully draped in green screen. One master camera followed a pre-determined track on the first set with a slave camera matching its motions on the green screen set. The non-green screen camera was scaled up 33% to accommodate the scale change.
The Bag End scene was finished in only four takes but it took 18 months to blend the two sets seamlessly together in post-production.
To create the scene with the trolls a virtual production stage was set up next to the live action stage. Footage from both sets was overlapped onto monitors and refined in the post-production process.
The chase scene was first done practically and then everything was replaced by a digital version except for Radagast himself. It took the programmers about a year to write the software.
Azog was originally played by an actor but the effect did not work well so Azog was created digitally, which took around six weeks.
The shots of the goblin cavern were mostly digital, with only a few practical builds used. These were shot mostly for reference and to aid in the actors’ performances, but were later replaced digitally.
The swinging rope bridge scene was entirely digital except for the eventual rope cut. The animators themselves donned motion-capture suits to simulate the dwarves as they stumbled and jumped off the swinging bridge.
Motion capture was used to create the sword fight between a goblin and Bilbo, though the goblin fighter was later scaled down in post-production. Bilbo’s face was digitally replaced since a stunt man was used in place of Freeman.
Gollum was completely rebuilt for The Hobbit, with more details in Gollum’s face than in his entire body in The Lord of the Rings. He was built as a virtual biological creature with complete skeleton and musculature to make him as realistic as possible.