Simulations turbocharge destruction in vfx
It’s been a rough year.
We’ve seen Los Angeles swallowed up by an earthquake, New York obliterated, and other waves of destruction caused by motor vehicle crashes and sci-fi baddies.
Once such mayhem had to be filmed with models and miniatures, and if it was digital, it had to be animated by hand. Miniatures are still a staple in this area, but this sort of destruction is increasingly put on the screen with a simulation — combining complex physics, arcane math and massive amounts of computing power.
Marc Weigert, who supervised the visual effects on “2012” along with Volker Engel, says, “A high-rise building, for example, might have a metal structure, cement walls and windows. In the computer you build all of these parts separately and give them the properties (of their real counterparts). For instance, a brick wall breaks totally differently from a concrete wall. The computer calculates what each material does and how they interact with each other. For example, a piece of glass hits and bounces off concrete.”
Simulations have become very popular for images of mass destruction. “It is used so much because its adds spectacle to a film,” says Industrial Light & Magic’s Ben Snow, who served as vfx supervisor on “Terminator Salvation.” “I think it is the art directability combined with increasingly realistic simulations that make it a really good way of achieving these spectacular shots.”
Simulations were a big part of “2012’s” Los Angeles earthquake sequence, in which a family flees by limo to the Santa Monica Airport and takes off in a Cessna, narrowly escaping by air as the city collapses and the Westside slides into the sea.
While a simulation renders an accurate picture, Weigert says, “When it’s 100% correct, it is too boring.” In that case, artists augment the work with hand animation to make the images more exciting. “For instance,” he says, “the story (of the earthquake scene) meant that one glass building had to break in a very specific way.”
“Watchmen” vfx supervisor John “DJ” Des Jardin used massive simulations for the movie’s climax, as superbeing Dr. Manhattan is framed for the destruction of New York.
“We wanted to be specific with the physical choreography,” Des Jardin says, noting that the destruction was simulated in the computer with hand animation for control.
“We didn’t want a nuclear blast. We wanted it to be mysterious. So we had to come up with a specific idea of what the physics of the event was and the timeline. It collapses in on itself and pulls things into it, so you see dust and debris. Then, when it goes down to nothing, we push thing out, and there is an area of almost zero gravity where things start to float.”
Simulated destruction also played an important role is this year’s sci-fi tentpoles, including “Terminator Salvation.”
In one sequence, Motor Terminators chase a group of the movie’s heroes, who try to outrace them in a tow truck. The truck plows through cars and has a head-on collision with a station wagon, flipping the oncoming car.
“The first approach was to simulate it on set with a rig. If you can do it for real, always try to do it for real,” says Snow, but the result was not exactly what the team was looking for. And so the shot went into the digital realm for additional work.
“The practical explosion was used to help us look like the car is kicking up dust and debris. But then once the car lifts off the ground, it is completely replaced with CG,” Snow says. “(Hand) animation gave us the dramatic choreography, (digital) simulation gave us the ability to take that dramatic choreography and make it look physically real. And then we used practical dust, and the initial explosion allows us to bring back some of the reality.”