Onscreen chemistry was not only important to Joss Whedon for his vision of The Avengers (including well-placed humor to lighten the load) but also getting the Hulk just right because he's the wild card. It turns out the third time's the charm for the Big Guy in this Marvel extravaganza. In addition, Whedon wanted a few tweaks for Iron Man as well considering he's the lead superhero.
ILM, if you recall, previously worked on Ang Lee's Hulk, but this was a far less cartoony rendering, according to Jeff White, ILM's visual effects supervisor. "We really wanted to utilize everything we've developed the last 10 years and make it a pretty spectacular Hulk," White suggests. "One of the great design decisions was to incorporate Mark Ruffalo into the look of him. So much of Hulk is based on Ruffalo and his performance, not only in motion capture and on set but down to his eyes, his teeth, and his tongue. We collected a huge amount of data and, thankfully, Mark is just the most agreeable person for the series of trials we put him through. We did many different types of image capture and he did a life cast of his head, hands and feet for us. Every pore and every blemish came from Mark, even his fingerprints. It was great not having to make everything up.
Whedon talked a lot about anger and rage at the beginning of the project and what they mean. Ruffalo took inspiration from The Incredible Hulk TV series, which he watched with his son. "Poppa, he's so misunderstood," Ruffalo's son observed.
"There's a moment when [Bruce Banner] consciously makes the decision to transform into the Hulk. There's something really powerful about that," White adds. "Our Hulk not only looks really good around the eyes but also has body hair, arm pit hair, nose hair. We knew we were going to have a lot of close-ups, and so it had to be more than just CG skin. We added beard stubble and salt and pepper graying around the temples to match Ruffalo."
The other quality that Whedon wanted to emphasize was a wrestler physique and vibe. Yet the Hulk has his soft spots, too. He's actually got a bulge around the waist. White calculated a rough body mass of 1,000-1,600 pounds. But when the Hulk gets angry there was lots of room to pop the muscles and veins and see all of that flexing happening.
Also key was making the Hulk a lot less saturated. "It's a more believable skin tone green," White says. "We kept pulling back on the saturation because he would come out of the box very vibrant. He's got to stand next to the other Avengers and look natural."
Indeed, the animators got the mass right along with his facial expression. "You're working in Maya in very low-res and he's got a huge brow and bushy eyebrows," White continues. "But his expressions were lost when we rendered it because the brow would cast a lot of shadow over the eyes. Just a few pixels up or down of the eyelid made such a difference if he felt angry or surprised. There were many rounds making sure the performance came through during rendering and compositing.
"The Hulk was built with our first procedural shading project in which the TDs had control of the skin qualities in different areas and we had the ability to dial up or down dust or scorch levels per shot to alter the look depending on the [mayhem]. Also, when we first started lighting him we took a traditional approach for us with a lot of rim lighting and contrast, especially in New York City. But he stood out above the other Avengers too much, so he wound up flattening out his lighting. We worked with the shadowed, top-lit look and added lots of kicks and rims on him. One of the trickiest aspects was dialing in the sweat level. We wanted him to feel sweaty but not plastic. We utilized beaded sweat (with a lot of breakup) rather than the broader sheens to stay away from the plastic look. The jumping and crashing and environment interaction needed to be believable."
Meanwhile, the Transport is the armored vehicle that lets off aliens during the New York invasion. It's like a worm that flies. "The animation challenge was figuring out how it flies," White explains. "We didn't want it to look like a porpoise and so finding the right speed was tough. If it went too fast, it looked small, but if it moved too slowly, it looked boring. We added electricity crackling down its side and it has heat wash coming from under its wings to stir up the ground."
As for Iron Man tweaks, ILM introduced the Mark VII suit. "We're back to a round RT on his chest but the biggest change was giving him a rocket pack. That was a conscious decision by Joss to give Iron Man different poses and not have his hand always as part of the thrust component. We also provided a little extra weaponry with a hand laser and thigh missiles."
Weta Digital got to play with Iron Man, too, especially for the mountain top fight with Thor. "We shared assets back and forth with ILM, but our pipelines are unique and it's hard for other assets to plug into it," explains Weta's VFX supervisor, Guy Williams. "But in this case, we got their models and we had to redo the texture spaces because the way we texture maps is different. We use a system called Udim and instead of putting all of our texture spaces from zero to one we lay them out in this very large grid so there are individual zero to one spaces. It allows us to have thousands of maps on a model and not have to do any arbitrary system for defining which spaces go to which maps.
"To migrate ILM's texture spaces to ours, we use ray tracing. We look at their turntables and just try to mimic it. In this case, we also had the beautiful suit from Legacy and we were both trying to up our game. We really got into the multi-layered car paint with the clear cut polish on top for Iron Man's finish."
Weta not only created a lot of destruction during the mountain top fight but also during the preceding Museum Square sequence (filmed in Cleveland but refashioned to look like Stuttgart) and then during the later Helicarrier attack. Weta uses Maya's particle solver for dirt, dust particulates and sparks. When large quantities of debris were simulated, they were also in Maya's regular particle solver and instanced as geometry at render time.
The secondary motion for trees and plants was simulated with a plug-in curve solver in Maya (on the render wall). The curve animation was applied to the trees at render time in RenderMan with another in-house plug-in. Most hero close-up destruction required enough art direction that they combined both fractured and prefecture techniques. Mid and distant destruction was mostly procedural or even rigid body grenades (emitting rigid bodies from a particle emitter, part of Weta's in-house rigid body toolset).
Method Design in LA created the titles (main on end) for The Avengers. Steve Viola, creative director, states, "This piece was a 2 minute self-contained main on end sequence created entirely in CG. For each of the shots in the sequence we designed, modeled, textured, and lit all of the environments and many of the foreground objects. We received assets from Marvel to include in the piece, then heavily re-modeled and re-surfaced them to create a post-battle macro sequence. We also designed a custom typeface for the Main Title ‘The Avengers’ as well as 30 credits set in-scene.”
He adds, "Many of the shots in the piece employ complex transitions that proved very difficult with varying lenses, scene depths, and text positioned in stereoscopic depth. The most difficult shot to execute was the final transition to a space-scape created by Digital Domain. We had to work back and forth with Digital Domain and Marvel to seamlessly tie our tight macro camera into their extreme-wide shot. Not only did it prove difficult to dial-in depth and perspective in stereoscopic, but it was also a very important connection that had to be choreographed with other FX timing and music cues so that it was perfectly seamless.” Tools used for the titles included Maya, Mental Ray, VRay, Adobe After Effects, Adobe Photoshop, Adobe Illustrator, Nuke, zBrush, Boujou, Final Cut Pro, Rush Render Queue, Qube and Fontographer.
"We set out to create a beautifully realistic macro sequence, featuring the battle scars of our heroes. The intense battle sequences of the film have put these characters through a war, and we needed to reflect that in a new way. The flowing camera moves through our scenes as it investigates the damage and toll it took on our heroes. The minute attention to detail, mixed with the macro rendering and stereoscopic compositing were all combined to dramatic effect and required the latest in technologies to execute," he concludes.
Bill Desowitz is former senior editor of AWN and VFXWorld. He's the owner of the Immersed in Movies blog (www.billdesowitz.com ), a regular contributor to Thompson on Hollywood at Indiewire and author of the forthcoming James Bond Unmasked (Spies), which chronicles the 50-year evolution of 007 on screen and features interviews with all six actors.