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Can you give us an overview of Digital Domains work on 2012?
David Stephens: The bulk of the work picks up basically about half way through the Escape from LA sequence. We actually pick up with a nice shot flying over the Golf course which is at the base of the Santa Monica airport. Which you see a big crack open up and swallow several houses and trees. Then it picks up basically at the airport. There is actually a small number of shots where the family is sitting there on the tarmac. They had a moving set that had the ground actually able to flex and wobble. We had to extend that off in to the horizon. Add on all the planes and other props that were on the runway’s reaction to that, so they had to wobble the buildings. Of course, structures and hangers would be falling down.
From there that leads into the actually collapse of the runway. The enormous fissure that opens up, and the flight through that and they emerge of course downtown and fly through it. It eventually ends up with the last two shots of seeing California sliding off into the ocean. That chunk defines the majority of what we did. We did do a little in Washington DC, with some ash shots, and the Washington Monument collapsing. The vast majority of everything was in the latter half of the Los Angeles sequence.
What was the biggest challenge on 2012?
Stephens: Mostly data load, you’re talking about a tremendous number of buildings and structures, large scale land scapes and what not that were crumbling. Most of this was an exercise in trying to apply rigid body type techniques and various things. Very, very large scale scenes, large numbers of buildings a lot of complexity in the building or structures. Having that tied in with a vast array of volumetric effects also that had to cover these very large areas. Lots of planning and logistics in terms of trying to put together so many things that had to be so many different layers. Of course your later layers had to depend on the previous ones, it’s just that whole thing of trying to organize that and keep it straight, it was a lot of work.
How do you go about creating the destruction in Los Angeles scene?
Stephens: When we started off we had a lot of extensive previs done on the shots that we received,. At that point we had allot of choreography they had actually planned out for when what building tips into what building and various things. The first part of it would be just going through and blocking and make sure we had gotten the director’s vision of the action going on in the scene.
You have to start off usually with the primary the largest structure or objects that we were having to break up. This would have to go through the demolition pipe line which the buildings themselves were all most of them were picked out of real buildings from downtown and others were things that had been modified or changed a bit. You had to have the buildings built to spec, so that it would work with the destruction chopping gizmo, that would actually break the thing up into small pieces. It would then go through an effects rigging process to have all the joint strengths and constraints that glues the building back together so that it essentially remains a cohesive whole.
Then you would have to apply whatever previs animation that had been done. That would have to be applied so that if the building is actually falling over. That initially was supplied by the animation we were doing, then selectively the parts of the building were released and turned dynamic and those things actually crumble and look pretty. At that point it’s really getting those performances bought off on and getting those looking nice. Then if other simulations around them whether it’s like small debris and glass or the dust and volumetrics. All those would be starting on those buildings or if that building crashed into another one then in allot of cases you would sim that second building after the fact using the first one as a collision body. You just keep stacking these things and working down stream until you have built up all the layers necessary.
How did Digital Domain incorporate Bullet (RBD system) into their pipeline for 2012?
Stephens: Yeah, Bullet is actually a good part of the pipe. Essentially, I think this is becoming more common is taking the game engine physics and being able to bring that in to one of the large packages. In this case it was Houdini, but we essentially wrapped up Bullet into a plugin in Houdini and built a pipeline around that. That eventually ends up being everything from a lot of the things that actually chopped up the geometry and glue them back together, joints and constraints. All that is then set up to work with basically help bullet conceptualize those dynamics, joints and constraints between objects. You basically end up with a series of plugins or networks that support the basic Bullet engine at that point, that was a big part of our process.
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