Completely new techniques were required to pull off this very real looking drama in space. In keeping with Cuaron's style, the opening shot was 13 minutes-long, instantly pulling the audience into the drama. This new tech were brought into play to create the stage of zero gravity. "The previz was a pretty intense process," understates Webber. "It had to be created to an advanced stage and then used to illuminate the faces of the actors as they are seen floating outside the Shuttle holding bay in orbit." This stage was almost entirely CG. in fact, everything but the faces of the actors in the helmeted visors. Even the fingered gloves of the crew fiddling with the computer board before the drama begins, were rendered to the appearance of being completely real. But they weren't. "This was mostly keyframe animation, while there was some motion-capture at some stages as well," says Webber. "Of course, it's really hard to use motion capture to depict a zero gravity environment, but again, we could have done small mo-caps and spent all that time on it, but then you'd have to fit it into the shot and keep it looking natural."
One of the main rigs was used on GRAVITY was based on a camera robot arm and the LightBox. Moving the lights on the robot arm was proving cumbersome, so the actors were moved inside the LightBox and this was moved around them, with the least movement to them as they could muster. "We came across a company called 'Bot&Dolly' that shot ads in San Francisco," explains Webber. "They put a camera on a robot. This was a similar robot that was used to assemble cars and furniture in a factory. It was a bit like a motion capture but with more flexibility and more speed. We added extra features as well, and everything was computer-controlled. Everything was being run off a 'platform of geeks', as the cinematographer always called it."
In the first wide exterior shot of Sandra Bullock arriving at the Tiangong in low Earth orbit, we are starting to see light streaking from the extremities of the solar panels and antennas being buffeted around. This is plasma, flames being generated off the sharp edges of the large, gangling space craft. This whole structure is still in orbit, but hitting the upper reaches of the atmosphere, going at tens of thousands of kilometres an hour. As the sequence progresses, the effect needs to become more pronounced. More immediately violent and hot, around the edges, some parts are actually being shaken out of place and being ripped away. This revealed a whole range of internal geometry that RSP modeled and placed in situ. What made the lighting of this sequence an even complex challenge for the RSP crew was that there was an additional balancing act. The sun was rising over the vast crescent Earth in the background, with all the complex mountainous and cloud textures and cities rolling underneath. There were a number of conflicting effects going on in the one shot.
Re-entry of a spacecraft is something that everyone know happens, but no-one has been able to film it from outside the craft, as we all know. There's nothing on YouTube other than earth-bound shots of Skylab breaking up and some shuttles on their way in. Creating this for a movie is open to interpretation, which makes for an extra challenge. "What does 'real' look like?," asks Clark. The videos of NASA testing various ceramics in the face of fast air speed gave some clues as to the colors and glows to prepare. "There's reference of the shuttle and Apollo missions re-entry."
The Tiangong station isn't built as a particularly strong structure and as people know space stations don't hold together when they re-enter. When pieces are ripped off the Tiangong, before they leave screen, they explode into many pieces which need to be created and modeled. They all are being super-heated along the way and showing ionisation effects of their own. There's a lot going on in every shot. Quite a few monumental management tasks.
Rising Sun Pictures had also to create views of the Earth which were a range of altitudes, from the point of re-entry, down through to the kind of height where the chute is deployed at 30,000 feet. There were a lot of public domain resources that the matte painting team used, but also there was a high-altitude balloon deployed to capture their own aerial shots. "We hired a group of engineering students from the university here in Adelaide," explains Clark. "Tim Horus Ballooning was supplied with a high-end prosumer camera and we gathered some incredible shots. As the balloon ascended, the payload is spinning around, so we set up the camera to shoot a five shot burst, and we stitched those shots together in a 12K panorama from about 45,000 feet. A lot of unique events happen as you look out along the horizon tangent. This gives you a really strong sense of what it's like at the edge of space." The Horus Ballooning project gave RSP thousands of images to use to help show what it was like to be at that required altitude.
Rising Sun looked back at some of the research during the production of Green Lantern, on atmospheric shaders, and brought that into the mix to replicate the light scattering model. "In that movie, we had a couple of fighter jets flying around at 60,000 feet and we had a lot of draw on computationally there," says Clark.
The Tiangong station was built at Framestore and the digital asset was sent across to RSP to finalise and use for the re-entry sequence. "They built the Tiangong model because they had to get Sandra Bullock into it," explains Clark. "Framestore built a full sized model of the Shenzhou re-entry capsule which they took to a lake outside of London and dropped into the water from a crane."
More imagery will be included as more are released by Warner Bros.