Mr Letteri and his team won an Oscar for their work.
This posed huge challenges for the visual-effects team, led by Mr Letteri.
Even then, Mr Letteri and his team were able to control Gollum's movements solely using Mr Serkis's captured performance only 20% of the time.
As actors are transported into virtual worlds where props, costumes and sets are drawn rather than built, there is the potential for job losses, but Mr Letteri thinks job transfers are more likely.
The film's visual effects supervisor, Joe Letteri at Weta digital, in New Zealand, and his team created a sculpture which was scanned using lasers to create a digital, three-dimensional model.
