Issue link: https://digital.copcomm.com/i/147928
Continuity body into the water. We couldn't create one asset that would quickly make every shot look good." Instead, the team created a low-resolution base fluid simulation and layered higher-resolution simulations exactly where needed for each shot. In one sequence, for example, the harbor water is flat, so areas outside a fight zone could have a lower-resolution simulation and areas around the creatures higher-resolution simulations. "That allowed fast turnaround," Hopkins says. "We could get a buy off on how the creatures disrupted the surface. Then, we could work on how the white water would look and how much it would cover the creatures." Velocity-damping controls helped the artists affect the speed of the splashes, and that, in turn, helped keep the water moving at a rate that was in scale with the monsters. "If we did a simulation without the damping controls, it looked like two people in rubber suits splashing around," Hopkins says. "The speed of the water helped sell the scale of the creatures." To control how much water could cover the creatures, the artists used a procedural technique to specify the depth of collisions. "Guillermo put the camera low to the water, as if it were on a boat," Hopkins says, "Most of the time the camera looks up. So, we have a camera five feet above the water when a 250-foot creature falls into the water 50 feet away." If they had simulated the water dynamics with real physics, the collision of monster and water would have created massive bulges, ■ MANY OF THE BATTLES between the Jaegers and aliens, such as this, happen in digital oceans and rain. massive waves, that would have covered the action. "We found that if we sliced off the collision at 10 or 15 feet into the water, we would get a nice bulge that we could control. That was the key to balancing the scale." Water Works Rain falls onto these massive characters and cascades down their surfaces – two separate problems. "Because of the scale of the shots, it's hard to realize how fast the camera moves through the air," Hopkins says. "If the creatures were people, you would have the camera on a 10-foot dolly, rolling slowly, and the falling rain would look vertical. But to get the same relative motion of the camera at this scale, the dolly would be 500 The giant Gypsy Danger, the main Jaeger, battles monstrous alien creatures throughout the film, and in doing so, receives upgrades and suffers damage. All told, the crew worked with 21 different versions of the battleshipsized, two-legged, two-armed machine. "Continuity was a challenge," says Visual Effects Supervisor Lindy DeQuattro. "But it was more of an issue for us than Guillermo [del Toro]. "He'd say, 'This is an art form. If the shots are beautiful and the story is told, I don't care if the left foot is exactly 10 feet across the cut.' But John [Knoll] is very scientific. His mind is focused on things being real and physically accurate. [Discontinuity] kind of freaked John out more than [it did] Guillermo." One reason the artists at ILM pay attention to small details is because they know the fans will. "We're the ones who hear about it," DeQuattro says, "even before the film is released. In the Comic-Con trailer, we had a car on the Golden Gate Bridge. One fan on one website said, 'Oh, that car was not available in the US. It was only sold in Japan.'" So, did they replace the car? Yep. "We changed it out," DeQuattro says. "The shot has to be accurate." – Barbara Robertson feet and the rain would whip sideways because the camera would be moving 50 miles per hour. So we had controls that the artists could use to compensate for the camera velocity." Thus, to create shots in the rain, not in a hurricane, the artists could choose how fast the water particles fell. The rain cascading down the creatures' surfaces presented another problem. For reference, Hopkins looked at waterfalls pouring down high cliffs with wind blowing on them. "The moment the water falls, it's aerated by the wind," he says. "I told the artists, no meshing of the water. No surfaces in the cascades. If the creatures had water blobs coming off them from meshing, they would look like people in suits. I'd say, 'Imagine you threw a bucket of water off a 25-story building. You'd see it vaporize.'" To make the cascading rainwater look interesting, the artists used air displacement caused by the creatures' movement. The same idea worked for white water in the water fights, as well. "The creatures in the fights create their own wind," Hopkins says. He likens it to the blast of air someone standing near a freeway would feel when a big semitrailer truck zooms by. "Now, imagine this massive monster," he says. "Water doesn't just fall with gravity behind it. You have air displacement. Air fields are what helped make the white water simulations look real. This was such a great challenge to take on. It really pushed us." Every time we think we've seen the biggest effects ever, a new film comes along that pushes the art of visual effects larger. The challenges ILM had with scale seem obvious at first glance, but when we dive deep into the ramifications, the work of the artists who met that challenge becomes even more impressive. ■ CGW Barbara Robertson is an award-winning writer and a contributing editor for CGW. She can be reached at BarbaraRR@comcast.net. CG W July / August 2013 ■ 45