James Cameron originally attempted to get this film made in 1999 as his immediate follow-up to Titanic (1997). However, at the time, the special effects he wanted for the movie ran the proposed budget up to $400 million. No studio would fund the film, and it was subsequently shelved for almost ten years.
The movie is 40% live action and 60% photo-realistic CGI. A lot of motion capture technology was used for the CGI scenes.