CGSociety :: Production Focus
26 November 2009, by Renee Dunlop
It's just thrilling to watch my apartment plummet into the Pacific Ocean along with the rest of Santa Monica, California, and the world. It gives a whole new meaning to the phrase, 'there goes the neighborhood'.
One of my own neighbors, Digital Domain (DD), was the culprit for some of my favorite stomping grounds' demise in Roland Emmerichs' latest visual extravaganza.
Emmerich worked with several previs and FX companies to handle the extensive workload this film required. Pixomondo (Germany) was paired with Digital Domain to provide the previs for the Los Angeles escape shots working out camera moves, blocking of major elements, and the massive destruction. While Pixomondo was working on the previs, DD's VFX Supervisor Mohen Leo was in Vancouver involved with preproduction, handling the blue screen shoot, while DD in California started on the R&D. This was in August 2008, and continued until about December when the shots were turned over to DD's team of roughly 150 artists and programmers, who then worked on post until July of 2009.
In the LA escape sequence, Cusacks' character has chartered a plane at the Santa Monica Airport to rescue his two children, ex-wife, and her new boyfriend. But as the plane is trying to lift off, an earthquake causes a bottomless crack to open along the runway, stretching forward into Los Angeles as walls of earth and rocks collapse around the plane when it attempts to take off.
As the chasm widens and the surrounding landscape drops into its depths, it creates a suction that nearly pulls the plane down with it. In a white knuckle attempt to escape, our heroes pull up in time only to find themselves dodging falling skyscrapers as they try to escape the city, which eventually tilts up and slides into the ocean (taking my apartment and the Digital Domain facility with it.)
As our heroes race to the airport, the camera pans up over a local golf course, utilizing one of the few shots DD had a plate to work from. The majority of the plate is live action, with digital houses and portions of the road in digital. The hundreds of toppling trees were done procedurally. According to DFX Supervisor Darren Poe, "That whole environment was done with photographs and reprojections onto geometry. We had to model every single house, every tree, every telephone pole.
Digital doubles, cars and progressive damage, mail boxes, shrubbery, newspaper boxes, recycling bins, concrete posts, stop signs... We spent many months at dailies looking at concrete posts and stop signs, it was very exciting," he chuckled. "We had a helicopter fly over the golf course and shoot continuous footage panning up to downtown. From that we extracted the stills we wanted to use to build the projection system."
The practical runway set was a plywood framed platform with pneumatic cylinders topped with a tarmac type texture. The construction allowed for the platform to flex, and it was filmed utilizing the available roiling motion that represented the quake, requiring careful matching to the digital set roiling. Ground cracks and other debris were handled with 2D tracking, requiring a lot of paint work.
It was CG Supervisor David J. Stephens' job to manage the challenge of making the sequence look realistic while managing a heavy data load from a collapsing ravine that stretched off to the vanishing point. "Simulating the sequence from scratch would have been incredibly prohibitive, so we developed a fairly nifty library system where we modeled up chunks of ravine, each about 100 yards long, and several layers of simulation to collapse portions of the wall, and then layers and layers of rocks and small simulated particles and a boatload of volumetrics on top of that. We did about eight of these, but the data we had to keep online for just one was really quite high. I think it took a good three or four terabytes to hold the whole library."
Each section collapse ran for roughly 400 frames and each could be repeated as needed, totaling to roughly 50 or more as the plane flies through. This process allowed for enough control when and where the walls would collapse while giving enough frames to get through all the shots. "That was a multi-month project," said Stephens "not only on the R&D of the rigid body solvers, the look development of the crash, and the volumetric elements, but also the pipeline issues and getting it set up in a way that was reasonably manageable to push the shots out."
Roughly half the buildings around the airport are digital. They were rearranged for aesthetic reasons, putting the more interesting buildings in view of the camera. Controls were added so the direction of collapse could be art directed, and subtleties such as digital planes parked on the tarmac were run through a rigid sim causing the wings to flex and jitter. "We would do long simulations, running out about a thousand frames, shaking the ground digitally allowing the buildings to respond to that, slowly decomposing themselves. Usually we did the smoke and dust custom for each shot."
