He had this to say about the underwater filming technique.
"We have kept a team of digital artists on from Avatar in order to test how we can create performance capture underwater. We could simulate water [in computer graphics], but we can't simulate the actor's experience, so we are going to capture performance in a tank."
He goes on to talk about how they brought the first film together.
"We are looking at [techniques including] what we did before with reflective markers, how we record reference photography so that as we are going through the editorial process and the postproduction workflow, we can see what the actors did and make sure that the final performance up on screen represents that.
He also discussed the 3D aspect of the movies.
"3D is evolutionary not revolutionary, and it will take time to come to market. But look at Russia and China, where the 3D screens market is phenomenal. In emerging markets, communities are going to theaters for the first time and are experiencing film in 3D - that's what they think of as a cinema experience. To show them a 2D presentation is a step back for them. [Conversion] will never be a comparable choice to native 3D shooting. As good as conversion can get, it's two and three quarters 3D and never true 3D."