Third-generation special effects supervisor Jeremy Hays talks about producing realistic snow, rivers and cracking ice on the new film adaptation of Jack London’s famous novel.
As a third-generation special effects supervisor, Jeremy Hays grew-up in the movie industry, witnessing firsthand a variety of filmmaking approaches that were sometimes successful, but often times not. His own resume is diverse, ranging from Hearts in Atlantis, to The Equalizer, to Once Upon a Time…in Hollywood, where he also makes a cameo as a flamethrower trainer. And for Hays, failure is always a learning experience. “On any film, what I do first is analyze the creative elements and then talk with the director, producers, or writers, to get an idea of what their focus points are,” he explains. “When designing a special effect, you want it to fail a few times in the shop before actually doing it in front of a camera. Having an effect that is 80 percent effective right out of the gate can be misleading, as that might be as far as it will ever get. Some projects that are fast paced don’t allow you time to test, so you have to tap into the experience of all those failed jobs that make you go, ‘That’s not going to work.’ Through those failures, you increase your proficiency and accuracy.”
Hays, however, is not set in his approach to developing special effects. “I was fortunate to start [my career] in the middle of the [transition between] old and new ways, so I never got deeply-rooted in the ‘winging it’ style of special effects,” he says. “When I sign onto a bigger project, it’s good to have somebody who can do SolidWorks or 3D CAD, as they can help develop things and foresee problems. Technology has definitely allowed us to do some cool and advanced stuff, though there has been a learning curve in how to implement it effectively.”
Call of the Wild, an adaptation of the classic Jack London novel, marks the live-action directorial debut of Chris Sanders, best known for animated features How to Train Your Dragon and The Croods. As the film’s special effects supervisor, Hays tackled a variety of practical effects, all integrated with the film’s visual effects. “The biggest challenge and the most fun was creating, in a real-world setting, the effects you normally see in an animated feature, and understanding that some of those can’t physically happen, which means you have to find the compromise,” he shares.
Initially, Call of the Wild was going to be made similarly to The Jungle Book, with partial sets and heavy reliance on bluescreen. “But then,” Hays reveals, “they realized there was going to be a lot more actor interaction, and some of the Gold Rush towns were going to have more people. What was going to be extensive stage work at Los Angeles Center Studios ended up being limited; we shot at a ranch in Santa Clarita for six or seven set pieces. We built a section of a flowing river to mimic where Jack Thornton [Harrison Ford] moves to at the end of the movie. There were a few encampments and Dawson City that we had to snow in.”
On set, an impressive surrounding bluescreen wall was built from stacked containers transported by Reach forklifts. “It always seems to feel more realistic when you’re outdoors,” he says in describing the decision not to shoot on an indoor stage. “Since it’s in a winter environment, you have a lot of campfires with toxic fumes. The water stuff couldn’t have been done onstage because it was too big. When you’re blowing snow around, the amount of particulate in the air onstage is huge compared to outdoors. It definitely helped to be outside.”
Most of the onset snow consisted of chipped ice because of how it interacted with the sled and eventual placement of the CG dogs. “It [making snow] was tough because of the temperature, the dirt, and the mud,” Hays remarks. “But we did have lots of Epsom salts. The one misconception about Epsom salts is that people think it’s salt-based. In fact, it’s magnesium sulfate, which is relatively friendly to the environment. However, when you add water, it breaks down into this slurry that can create corrosion. When you’re doing a big snow movie like this, from a practical effects standpoint, you don’t make a lot of friends! Because if it’s not ice creating mud, it’s paper snow, which is super messy. When people are walking through Epsom salt, it behaves more like sand, that in context, looks like snow. Sometimes you had to use ice for certain areas. People have learned to accept paper snow as movie snow. It will create footprints and do certain things that look good, but technically, doesn’t behave exactly like snow.”
Hays employed a combination of techniques to create winter in Dawson City. “Dawson City had porches on both sides of the town, so it’s a long main street,” he describes. “We would snow in the main parts of the action with chipped ice. It would create a natural berm or transition, so you could also do paper snow or Epsom salts in the background. That way, you didn’t need to continuously apply touch-up materials to melting ice. You have these 300-pound blocks of ice that get fed from a big box truck into a chipper; it comes out of a large four-inch hose and you shoot the stuff onto the ground. If you get the chipped ice deep enough it creates a thick insulated area. We had a lot of silks overhead, so we were able to fight some of the direct sunlight hitting the snow. Oddly enough, it melts from underneath; what you don’t see happening is that it creates these muddy rivulets that flow underneath the snow. Once the scenes start to progress and more people start walking on it, it breaks down in a way that requires you to re-snow the whole thing. We put down a base layer of white muslin to create a membrane between the mud and ice. Eventually, we started putting drains in certain areas. There wasn’t much prep time so in hindsight, we would have designed a better drainage system that would have helped us quite a bit.”
For the scene where the character Françoise (portrayed by Cara Gee) falls through the ice, a section of river was built on set. “There was a10 feet by 40 feet container that was buried into the ground, where a current could be produced that would simulate the river waterflow,” Hays states. “We put an ice surface on top. It had a clear acrylic trapdoor mechanism underneath the ice surface that created the support for the actress to walk on. We poured resin material on top that held everything together. As she uses the staff to poke at the ice, it starts to crack. The basic crack motion was controlled through visual effects. But for the moment when she falls through, we had these sheets of inch and a half acrylic that opened like elevator doors, but they are clear so you can see the water movement underneath.”
According to Hays, two months were spent developing the rig. “Years ago, we would draw something on a napkin and say, ‘This should work.’ Then you would start building it. Now, with the computers, you can design it and know exactly whether the pieces will fit together and how the mechanics will work. We discovered we had a three-quarter inch gap where we could put other ice pieces, which made it look like there was more material when she broke through. It took four weeks to construct.”
A current needed to make the river believable was created using 740,000 gallons of constantly recycling water. “In the tanks with the breakaway piece, it wasn’t too bad; you draw water from one end and put it back in at the other end,” Hays says. “Most of the time you focus on surface current, so it looks like moving water, which was easier in that environment. But, with the 300 feet long 10 feet wide river at Thornton’s cabin, that involved four huge 30-inch diameter outlet pumps taking thousands and thousands of gallons of water from a basin at the base of the river and reintroducing it to the top. If the river isn’t flowing, the water level lowers. The moment you start introducing a current, there is a surge in the water level as the water is flowing. When the water wasn’t moving there was a huge gap between the ice and the water. Once that water started to flow the water level rose so it filled in the gap. That’s also a consideration when you’re designing. You have to calculate the speed of the current, which determines what the space is between the ice and the water. We also designed a heated and filtered section so that Cara Gee could go in the water, flow with the current, and pop up 12 feet farther down the container off camera.”
In some scenes, a canoe gimbal was shot against bluescreen. “We began with Thornton and Buck getting in a canoe on our on-set river,” Hays shares. “They also shot some footage in Canada of a stuntperson in a canoe on a river running some rapids. The end of the journey takes place on the river we built. But there was one sequence in particular, where they wanted to do a cool camera shot, that had to be tied in with a motion control camera; the canoe had to move in a specific way, so we used a gimbal for those shots. On the gimbal, we built a counterweight that Harrison would push against that gave him some resistance in the way he paddled.”
Previs was used extensively in developing the various dogsled sequences. “With previs, you could design a sled pulling mechanism that was specific to the scene,” Hay notes. “Some of sleds used for stunts were made out of steel, and we had to mimic the wooden ones. There were six types of sleds used for different shots, like tipping over or crashing. In certain scenes, it was simple, such as them leaving town. Through a series of cables and pulleys, we would hookup to a Gator, a four-wheel drive off-road vehicle, where you could drive from point A to point B. We also built a speed controlled computerized winch that could be pulled 300 feet.” 
Intricate sight gags that Hays laughingly called “Stuart Little gag” were devised to make it appear the CG dogs were physically interacting with their environments. “Every time an actor interacts with a CGI element or vice versa, we must think about weight, gravity, mass and the resulting direction,” he explains. “Those things can be fun. There’s a scene when Judge Miller [Bradley Whitford] has to pull Buck along a long carpet that we needed to bunch up. We used cables underneath the carpet for certain stop points that we would stitch in. As the actor would walk, pretending to pull the dog, we would bunch up the carpet behind him. There was also a scene when Buck jumps on these two beds and the two little girls in each bed get launched into the air. We had to create beds that would collapse, recoil, and launch the kids into the air without a dog actually jumping on it.”
“The scene that I’m most looking forward to seeing is when Buck knocks the bad guy into this cabin that’s on fire, and then the roof collapses,” Hays says. “A stunt guy gets pulled through the front door, breaks the door and as he lands on the ground, the ceiling collapses around him. It was all done with cameramen inside. There were some flame bars, but we also had some fuel-based materials that were dressed onto the walls and furniture, that would be lit just before doing the stunt. They burned intensely for a minute and half, then self-extinguished. We built the main beams out of balsawood; they were put into these chambers, the air was sucked out, and a fire retardant was reinjected to prevent them from burning.”
Trevor Hogg is a freelance video editor and writer best known for composing in-depth filmmaker and movie profiles for VFX Voice, Animation Magazine, and British Cinematographer.
