VFX supervisor Holger Voss talks landslides, daring escapes and setting up a Montreal studio for Warner Bros. and Village Roadshow's disaster movie.
A helicopter, a car, a cliff and a daughter in peril – no disaster flick would be complete without them. And while it’s Dwayne “The Rock” Johnson leaping to the rescue in San Andreas, the staff of Cinesite were busy making it all seem real.
As VFX supervisor Holger Voss details, the studio handled two key moments in the film: one where the aforementioned car tumbles down a cliff in the aftermath of an earthquake and another where Johnson’s helicopter flies in to rescue the driver, his daughter (played by Alexandra Daddario). Naturally, the actors performed in the safety of the Australian set, far away from any falling rocks. “They had built a set with the car hanging off it,” Voss explains from his Montreal office. “The actress was in that car and they had a helicopter without rotors hanging above from a crane. Everything around it that is connected to that set and what we see behind the helicopter and in the valley below is all CG.”
Making that CG environment required a trip to California’s Glendora Mountains to capture extensive photogrammetry photography. “They were in the process of shooting the set piece, so we saw some rushes and we roughly knew what we would need to shoot and the angles we would see,” he recalls. “We came to LA and used a helicopter and ground survey to survey the whole environment.” The hope had originally been to line-up footage from California with the footage shot in Australia, but it didn’t go as planned. “There were a couple of shots with the set piece in Australia that were filmed with a crane like it was a POV out of the helicopter. We wanted to use that footage to try and shoot the background plate of the real cliff, but in terms of the line-up, it’s only as good as the pilot can manage to get it. It didn’t really feel like it was going to work out so we were basically prepared to build the cliff digitally.”
“The cliff that the director picked in LA wasn’t an actual canyon, it was more like a round-shaped cliff. They had marked a spot where we would inject the green screen set piece in comp and we found that we would have to augment and build the other side of that canyon. So very early on, we were preparing ourselves to possibly build the whole environment, and then basically do a CG background and just copy part of the green screen shoot into this background.”
The studio’s work on San Andreas began in July 2014 and concluded mid-April 2015. “For cameras we used 3D Equalizer and from there we go to Maya, then render in V-Ray and then into Nuke. We also used Agisoft for our photogrammetry work, which is the process of using a lot of photographs and then generating point clouds for modeling the cliffs.”
The automobile’s descent into danger was, as Voss put it, “a very special shot. They made a long shot that was meant to be slow motion and had the camera punch in on her face, her screaming, and then pull back to normal. What they actually tried was building a puppeteer rig for a real car with like four cranes to try to make this car fly and it never looked right. The idea was to do a partial stunt and a takeover, but then the Rangers on-site basically cancelled that idea, saying no car would go over the edge of this road. So on the day it was decided to then go CG, purely for practical reasons.”
San Andreas was the first joint project completed between Cinesite's London and Montreal studios. While Voss was mainly based in Montreal during post, the company's London TDs were largely responsible for writing some tools which greatly added to the project's rendering efficiency.
“We needed to be smart about how we would render the large amounts of vegetation,” he recalls with a chuckle. “A lot of the bushes and trees in the digital environment are CG and they’re all moving, so in order to render them properly they each had to be loaded separately at render time. Much of the lead development for this project was finding a way to cache the geometry here on the rendering machines in a form that was more efficient so we could render quuickly.”
Cinesite's London and Montreal teams held regular conference calls and dailies sessions throughout the day, reinforcing their transatlantic communication skills. “Setting up a facility while doing a show meant that communication had to be four times better. You need to be in the same time zone and find out when they’re available. There’s more planning and coordinating involved.”
Voss is happy with the end result of their labors, and notes that The Rock doesn’t rely on camera trickery to pull off his performances like some other summer action stars. While he never visited the Australian set, he states that Johnson “seems to do a lot of shots by himself. We didn’t have to do a single face replacement, so that obviously speaks for itself.”
So yes, all you Rock fans – if you’re in need of assistance in the Los Angeles area, he may very well be capable of saving you.
James Gartler is a Canadian writer with a serious passion for animation in all its forms. His work has appeared in the pages of Sci Fi Magazine and at the websites EW.com and Newsarama.com.