Raising the VFX Hammer for <em>Thor</em>

Check out the Thor trailer at AWNtv! [1]

What distinguishes Thor from all other Marvel superhero movies is that it introduces science-fiction by venturing to the cosmos and bringing the Norse god of Thunder to Earth for his humbling rite of passage. In fact, according to director Kenneth Branagh [2], they erred on the side of science, and that was the mandate for Wesley Sewell, the overall visual effects supervisor, in executing the 1,309 vfx shots, primarily created by Digital Domain, Buf, Luma Pictures and Whiskytree, but which also included contributions by Fuel and Evil Eye, plus a team of five in-house compositors.

In Norse mythology, there are nine realms that inhabit the entire cosmic tree called Yggdrasil. In Thor, we visit three: Asgard, Midgard (Earth) and Jotunheim. Thor comes from the advanced civilization of Asgard. "We knew we had to show Asgard as a real place, but one that is both futuristic and at the same time ancient," Sewell suggests. "All of our Asgard models and matte paintings were done by Whiskytree, supervised by Jonathan Harb. For the look of Asgard, we went for a blend of classical fine art and comic book history. Think JMW Turner meets Jack Kirby. These elements -- cinema/comic book/classical/sci-fi/futuristic/ancient -- are tough dichotomies to balance and require a lot of imagination to achieve. We also tried to incorporate the idea of using fractal geometry in the organizing, arrangement and design of Asgard. We figured that an advanced civilization who has mastery of the deeper concepts of life's inner workings might utilize fractal geometry. Between the work done by our production designer, Bo Welch, and his crew, and the talents of the Whiskytree artists, these polarized concepts end up coming together in a truly beautiful and fascinating balance throughout the film."

Jotunheim, meanwhile, is a frozen wasteland of a planet: home of the Jotuns, or Frost Giants, who are a violent tribal race of warriors. "Here the color palette is dramatically reduced," Sewell says."The look is an icy ode to the fine art of Caspar David Friedrich with the comic book flair of Patrick Zircher. Every effort was made to have our shots framed as a graphic novelist would but with the moving aesthetic of cinema. This cold snowy environment and all the CG Frost Giants were realized for us at Digital Domain, supervised by Kelly Port, including the formidable Frost Beast. The Frost Giants themselves are a combination of live-action actors and CG characters in the film."

Port adds that DD's contribution of 340 shots was handled primarily by the Vancouver office (though Venice worked on 85 of those shots). DD used Maya [3], ZBrush, Mudbox [4], Houdini [5], RenderMan and Mantra.

"The biggest challenge was the environment of Jotunheim," Port explains. "There was a lot of back and forth design wise about getting that balance between rock and ice so that it's not a pure white environment, and getting the architecture to look decayed enough so that you still see the remnants of a once great civilization. But we ended up creating quite a few buildings and because we're seeing it in a prologue sequence as well, where it looks pristine, we had to make all those buildings in a few different variations."

As far as the Frost Giants, they had to match the look of the live-action characters shot on set whose costumes were designed by Legacy. "Marvel wanted to extend that out and push the limits of the anatomy, making it a little less human," Port continues. "Our base Frost Giant was around nine-feet-tall. And we created 12 base models to mix and match in combination with the live-action Frost Giants, and that worked well having hundreds of these guys running around.

"The Frost Beast is anatomically like a cat but it charges like a rhino. It has fleshy tusks at the head and a big, bulbous head used for crashing through but also talons that it can grip the ice with. We were trying to create a creature that has evolved in this icy environment. Skin-wise, it's like a rancor beast/rhino."

The third realm, Midgard (Earth), is depicted as present-day New Mexico, where Thor is banished. This is where they did the least amount of augmentation with vfx. "Here the visual effects had to be as seamless and realistic as possible," states Sewell. "This is the realm we all know and, for this bit of cinema, we have to believe that Thor is really here. We were inspired by Edward Hopper and the comic book art of Oliver Coipel. Most of the visual effects [here] were done by Luma Pictures, supervised by Vince Cirelli, including the awesome Destroyer straight from the Marvel comic books. "

Luma used reference movies of rocket engines from JPL as inspiration for Destroyer's energy beam as though he's charging up, before firing. The blast and internal energy were created using a mixture of high velocity fluid simulations and dense particle renders driven by geometry.

During the battle between Thor and Destroyer, Thor spins his hammer at incredible speeds, creating a super tornado that lifts CG cars, debris and Destroyer into the air. Luma's in-house software programming staff designed tools for the vfx team use to help visualize the large amounts of data needed for the supercell generation. This allowed them to design the lighting and shot composition before rendering dense data sets.

For traveling the cosmos from Asgard, they used a rainbow bridge called Bifrost. This is a solid, crystalline bridge that leads from King Odin's palace in the center of Asgard out to the edge of a saturnal ocean, where it connects up with the ancient Heimdall Observatory. "The crystalline rainbow bridge and all the visual effects around Heimdall's Observatory were done by Buf, supervised by Nicholas Chavalier with supervising vfx art direction by Pierre Buffin," Sewell adds. "This is a beam moving so fast that it stretches the spectrum of light into what could be perceived as a rainbow. Buf did many of these blasts into space [Luma created others using voxel rendering techniques and complex lighting rigs inside funnels], including our stunning end title sequence, where we travel from Earth through a wormhole, past a black hole event horizon, on through a fractal increase in scale, until we behold the entire universe as a magnificent tree, a literal Yggdrasil. Then we zoom through its trunk and branches until we reach the top and find Asgard. Here we attempted to create a cinematic first where we ride from one destination to another across the cosmos with an exciting sense of scale, grandeur and breathtaking beauty."

Meanwhile, the stereoscopic 3-D conversion was performed by Stereo-D (Graham Clark was the stereographer), which mainly worked with actual geometries rather than volumetric illusions, while DD provided 80 some CG shots in full native stereo. "If you have proper geometries and project the original film image on it, you can 're-photograph' it with two virtual cameras in the computer," Sewell continues. "This is how it resembles true stereo photography. There is a bit of tearing and stretching that occurs in each 'eye,' but this is easily cleaned up with our typical visual effects paint tools. One of the other things that I liked about Stereo-D was that they were visual effects friendly. This is important because stereo conversion is essentially a visual effect using similar techniques and technology we use for the effects in the film. We should not only be compatible but also collaborative. Stereo-D embraced the opportunity and were excited by the possibility of this interchange."

Bill Desowitz is senior editor of AWN & VFXWorld.