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Editing Virtual Performances

One of the undoubted highlights of IBC2010 was a keynote session – part of the IBC Digital Media Training Workshops initiative – in which Stephen Rivkin described the challenging process of editing “Avatar,” the box-office blockbuster directed by James Cameron. It was so far from a traditional movie edit that the 45-minute presentation barely scratched the surface.

One point that Rivkin was very keen to emphasise was that “‘Avatar’ was not an ‘animated’ movie. Every character is a live performance.” Even the crowd scenes were performed with groups of extras tiled to build up the big set pieces. It all depends upon performance capture, he explained, and that transforms the editing process.

Illustrating his points with plenty of video clips, he showed how performance capture works, with each actor wearing suits covered with markers. To get expressions and natural-looking dialogue, markers were also applied to the actors’ faces: the way that lips move to frame words and the way that eyelids and cheek muscles respond to emotions was all precisely captured.

The actors were not stationary for this process, though. They were also acting, and interacting with each other, moving around green screen shapes, which would later become the landscape of the planet Pandora. Multiple HD cameras captured the movement, which led to the first part of Stephen Rivkin’s edit.

He took the multi-camera recording and made a rough cut of each scene. What made this process unique, though, was that, because none of this footage would appear in the final cut, he was free to cut together different takes without worrying about precise flow. Where two actors were in a dialogue, they could come from different takes – even when they appear in the same shot. It meant that Cameron could select the perfect performances every time.

Rivkin told the IBC audience “These were just reference cameras, which did not represent the final version. We created the edit, bearing in mind that it might not be the camera angles or framing in the final version. It meant that James Cameron was free to concentrate on the actors.”

This rough edit, which even included different body and face takes, was then sent to Weta Digital in New Zealand for the task of modelling the virtual characters.

Meanwhile, Cameron moved on to the next stage, which was to create the shape of each shot using a virtual camera, with reference graphics and rough renders of the characters. He could concentrate on the visuals now, confident that the actors are always going to hit their marks and deliver the lines perfectly.

From a number of takes and set-ups, Rivkin and his colleagues edited each scene to best tell the story, again not worrying about precise alignment, which would be smoothed in the virtual environment. Weta Digital then rendered each scene, a process which could take a year or more. Only when Cameron was happy with each scene was the final movie assembled.

IBC has a close association with “Avatar” as director James Cameron was a recipient of the IBC International Honour for Excellence, its highest award; an extended preview was shown at IBC2009 before its release and the full movie, in its extended special edition form, was shown at IBC2010.

Hearing from its Oscar-winning editor about the two-and-a-half years he spent on what he described as “an edit-driven process from beginning to end” was just one of the fascinating insights that only IBC can deliver.