Rare Mettle
Issue: Volume: 33 Issue: 5 (May 2010)

Rare Mettle

Industrial Light & Magic ups the action and heightens the look of the first Iron Man sequel.

It’s no secret now that Iron Man is technology whiz Tony Stark (Robert Downey, Jr.), the gazillionaire head of Stark Enterprises. The first film, directed by Jon Favreau and released by Paramount Pictures, ended with Stark’s dramatic revelation and earned more than half a billion dollars at the box office. So, what’s a sequel to do? More.

“I feel like we have more room to run on this one,” says Ben Snow, visual effects supervisor at Industrial Light & Magic (ILM), who landed a third Oscar nomination for Iron Man. Overall supervisor for the film was Janek Sirrs, who won an Oscar for The Matrix. “It’s a bigger film than the first one,” Snow adds. “[Favreau] succeeded in capturing the fun parts of the first one in terms of Robert Downey’s performance, and he upped the action. The effects are more spectacular. I think around 14 houses worked on the film.” In Iron Man 2, Stark is a rock star hero. But the government, the press, and everyone else wants the technology embedded in his heavy-metal suit. Stark’s tight grip on the technology opens the doors to a competitor, Justin Hammer (Sam Rockwell), who tries creating a duplicate suit. Then, a Russian madman with ulterior motives, Ivan Vanko (Mickey Rourke), persuades Hammer to build drones, not suits. Vanko, who has a smoldering chip on his shoulder, builds his own suit out of drone parts and becomes Whiplash. Meanwhile, Tony’s friend Jim “Rhodey” Rhodes (Don Cheadle), turns an Iron Man suit into a War Machine. What does all this mean? Lots of action. Lots of digital suits.

Tony Stark (Robert Downey, Jr.) makes his grand entrance in Iron Man 2 wearing the superhero suit he created. The stage and the first rows of people are real. Artists at Industrial Light & Magic created everything else—the Iron Man suit, the crowd, and the expo building—using computer graphics tools.

If the effects crews succeed, the audience will believe that Robert Downey, Jr. and Don Cheadle are inside the suits, but they rarely are, or at least not totally. For the last film, ILM created proprietary shaders that mimicked the metal used for practical suits so well that at times Downey’s suit had some practical parts and some digital parts. For this film, knowing that ILM could add anything he didn’t want to wear, Downey often wore an Imocap suit (from ILM), with a partial suit on his upper body and a helmet. Sometimes, only the Imocap suit. Ditto for the stuntmen.

“What was funny is that Don Cheadle arrived on set wearing the whole suit,” Snow says. “He saw Robert Downey, Jr. in tracksuit pants with [Imocap] bands on it. Pretty soon, Don isn’t wearing the whole suit, either. Legacy Effects did a great job of making the suits lighter and more wearable, but the actors were still reluctant to wear them. And even when they did, we ended up touching up the shots. I think there was no shot that we didn’t touch digitally.”

Suit Up
When we last saw the Iron Man, he was wearing a red and gold Mark III, a superhero upgrade from the silver Mark II. In this film, Stark keeps the Mark III, but with a few tweaks, more gold paint, and a few new weapons, it becomes the Mark IV and then the Mark VI. A retailored and upgraded Mark II now fits Rhodes rather than Stark, and, equipped with almost every gun in the book, becomes the War Machine.

In this shot, the actors’ faces, the grass, and the shrubbery on the right are the only non-CG elements. On set, Robert Downey, Jr. (left) and Don Cheadle (right) wore Imocap suits and partial helmets. ILM added the CG suits, replaced the helmets, created the digital drones in the background, and the rest of the environment. 

“The only suit we didn’t do is a nifty suit called the suitcase suit,” Snow says. “We did some artwork for it, but Double Negative ended up executing it. During their sequence, Ivan Vanko [Mickey Rourke], the son of a Russian genius who helped Tony Stark’s father develop the technology, uses his glowing electrical whips to lay waste to the suit while Tony is racing. And that’s the end of that suit, which is the Mark V.”

ILM worked directly with Pixomondo on that studio’s sequence. “The client knew the work was going through the third parties, but we supervised it and handled it all,” Snow says. “We sent the sequence to Pixomondo, where Justin Hammer is showing Ivan Vanko some drones he’s building. We built and painted a drone, and gave it to Pixomondo, and they did the shots. They did a terrific job. We also worked with Svengali, which did some matte paintings of the Stark house for us, and with The Embassy, which did a sequence with the damaged suit at the end.”

Although ILM still keeps most of its secret sauce secret, the studio feels comfortable sharing more technology and knowledge with the studios they deal with directly than they would otherwise.

“We still have to recognize that we have proprietary tools that give us some advantages,” Snow says. “But, our aim is to establish relationships with the third-party vendors where we know the people, know how to work with them, and build the same kind of trust that we’ve built with ILM Singapore. ILM Singapore has been a huge asset on both Iron Man films. Singapore has all our tools, identical workstations, security cards, everything, but this was the first time we have sent lighting work to them. They do top-quality work now that is not distinguishable from ILM. We want the same sort of situation with our third-party vendors.”

Just Like the Movies
“This new technology is fun,” says Doug Smythe, digital production supervisor, of ILM’s new energy-conserving lighting. The new energy-conserving shader set works within Pixar’s RenderMan and communicates with ILM’s proprietary Zeno lighting tools; Smythe created a suite of plug-ins for the new tools.

“It’s like moving from really good Impressionist paintings to photographs,” he adds. Smythe, who has received three technical Oscars and an Oscar for best visual effects in the film Death Becomes Her, is a photographer in his spare time.

“It’s fun to use the same kinds of techniques in the computer that I would use with a camera in the real world,” says Smythe. “I can actually work in CG and light a CG character the same way as in a portrait studio. We haven’t been able to do that until recently. We don’t have to ask, ‘What colored CG point light will approximate a light source? Do I darken or brighten? What hue?’ We just have a picture of the source light and use it directly. It’s liberating.”

Smythe explains: “You can take several pictures at different exposures to get an HDRI of a light source. That picture is the texture for the light. So, the CG light will emit light with the brightness and color at every pixel direction you had in that original image of that light source. If you move more than a fraction of an inch from the surface, the color from one square inch blends with the next. And farther away, you see amorphous light.” Just like light in the real world.

Or, the crew might take a large photo of an entire set and crop out a small, rectangular area of interest to use as a light source. “If we have a bonfire burning in a section of an image, we might take a rectangle surrounding that area and put the moving footage on an animated sequence of images,” Smythe says. “So, now we have a bonfire light that casts bonfire shapes and colored light onto whatever CG character happens to walk by. And we can put several of these throughout. Or, we might treat the entire spherical environment as a light. We can have round lights and rectangular lights. And we can put texture images on the lights if we want.”  

As light from these sources bounces through the scene using raytracing algorithms, collecting, reflecting, and absorbing colors, the energy-conserving calculations make sure that the sum of light reflected from and absorbed by the objects in the scene is never greater than the original light source, that it’s physically accurate.

“The total amount that goes out can’t be more than goes in,” Smythe explains. This formerly wasn’t necessarily the case with CG lighting, which often produced highlights brighter than the light source causing them. But, until HDRI, visual effects artists did not use photographs to calculate the entire amount of light in a particular location.

Now, the visual effects artists do, and ILM is using that information to calculate physically accurate digital lighting using light sources from the real world. “We have shaders for the surface materials, and different shaders for the various light sources and a bank of lights,” Smythe says.

The math for doing these calculations is not new, but computers haven’t been fast enough to process the calculations for film production, nor algorithms smart enough until now. Even so, ILM uses a technique called “importance sampling,” which steers the raytracing calculation toward areas that matter—usually the brighter areas—to help speed the calculation time. And, lighters can turn switches on and off during the multi-step process to trade quality with render time. 

“There’s a fight in Tony Stark’s house in Iron Man 2, in the kitchen and in his personal gym,” Smythe says. “The lighting is harsh, and he has tight spotlights in the ceiling that create bright circles of light on the floor.” As the CG characters—the red and gold Mark IV and the silver Mark II metal suits—bang through the rooms, the lights hit them and change as they move.

“The animators position the characters and move them around,” Smythe says. “Then a multistep process in the tool kit does the computations. The CG character affects the environment, and the environment affects the character.” For this scene, lighting artists who opted to use the new lighting solution especially benefited when a shiny suit fell to the floor.

“We could compute the illumination on the floor as indirect lighting using color bleeding [as before], or turn the entire floor into a light with bright spots where the lights shine down,” Smythe says. “We finally have something close to the physical result we’d get from a real light source. Brightness falls off with distance in the same way. And, it’s not just an approximation. We’ve done tests comparing CG lights to real lights on real objects. It’s not perfect, but we’re closer than we ever have been. And, I think there’s a noticeable difference, a richness and detail we didn’t get with the old-style point light sources and simpler surface shaders. Ambient and reflection occlusion were great tricks in the day, but we can do better than that now.” –Barbara Robertson

Costumes Are Characters
When the actors appear fully suited in the film, the suits are, of course, mostly empty geometric shells manipulated by animators to perform as if someone were inside. The artists paint, render, and light the suits—in other words, the CG characters—to appear as if a director of photography shot them on location.

Bruce Holcomb led the modeling team. Ron Woodall supervised the painters. And, Doug Smythe turned the studio’s new energy-conserving lighting technology into more intuitive tools. Holcomb and Woodall have worked together on so many films at ILM, Holcomb teases that people call them “Bron.” “We’re an amalgam,” he laughs. “That’s the best thing about this film­—our friendship. We help each other with jobs, and the process becomes very fast.”

Woodall adds, “I’ve been fortunate to work on a number of shows with Bruce. We’re like-minded in the things we think would be cool, so the days are easy and we have a lot of fun.”

For Holcomb’s group, the work entailed streamlining the Iron Man Mark III and adding more weapons, building War Machine (which is a modification of the silver suit), creating the drones, building the suit that Ivan Vanko’s character wears, creating suit parts to complete the partial suits the actors wore, and modeling damaged versions of the suits.

Woodall’s team painted texture maps for all the suits. For the last film, cleverly written proprietary shaders used the orientation of UVs to control the spread of the specular and achieve the suits’ brushed-metal look. For this film, the texture painters had an easier time. “Our entire lighting pipeline changed with Terminator,” Woodall says. (See “Shades of the Future” in the May 2009 issue.) “Before, the specular always spread perpendicularly to the brushing. To get a bow-tie specular effect on our burnished disks that matched the real suit, we had to unwrap the geometry in UV space and lay it out vertically to match the grain in a texture map. On this film, we could pro­ject the texture map with a clockwise gradient from black to white straight onto the geometry and it took about five seconds.” For the Iron Man Mark IV and VI suits, Holcomb, whose background is in industrial design, modeled in AliasStudio’s curve evaluation with B-spline surfacing. “I find it to be a very useful tool for the swoopy-type feel of models, like the Star Trek Enterprise and these models,” he says. “I always like to use B-splines to start a process, and in Studio, you define the curve first.”

The drones—one style for each branch of the military—all began with base-level geometry that the modelers propagated from one model to the next. “Because 70 to 80 percent of the parts were similar, we could immediately start painting,” Woodall says. Each drone, however, sports weapons and a paint job particular to its branch of the military. Army drones can fire an anti-aircraft gun carried on their backs. The Air Force drones fly at Mach speed. Navy drones shoulder surface-to-air rockets. And the Marine drone, the only one with a camouflage paint job, just looks tough. “The Marine drones were going to be played as the toughest, but we downplayed them to play up Ivan’s super drone,” Woodall says.

Tony Stark’s rival Justin Hammer (Sam Rockwell) builds robotic drones in the film. ILM put anti-aircraft guns on the backs of the Army drones pictured above, and outfitted other drones with different weapons that represented the Air Force, Navy, and Marines. 

To build the new War Machine suit, Holcomb and co-worker Rene Garcia started with Legacy Effects’ digital files for the practical suits, and then streamlined the suit and added weapons using concept art created at the studio and by Aaron McBride, VFX art director at ILM. For this model, the new drones, and the suit Whiplash kludged together, Holcomb worked with Autodesk’s Maya using polygons and subdivision surfaces.

“War Machine was a big, fun project for us,” Snow says. “We gave Ron Woodall and Bruce Holcomb a style sheet that showed what the weapons looked like, and then they went crazy coming up with new technology and new weapons.”

Even so, the artists kept the ideas within the limits of real mechanics. “We looked at how things actually get deployed,” Holcomb says. “We added a lot of flare to [War Machine], but he definitely has a real-world feel.”

The Unisphere in the lower left of the image is one of the few buildings still standing on the 1964 World’s Fair site in New York City. It’s also one of the few real elements in this image of the Stark Expo site in Iron Man 2, which ILM Singapore built and sent to ILM in San Francisco for final touches.

On the Surface
War Machine existed as a practical suit with a metallic-looking surface on set that the ILM crew used for lighting reference as well as a jumping-off point for the modelers. “We wanted to capture the feel of the practical suit, but Jon Favreau wanted to go beyond it,” says John Walker, lead technical director, who helped develop the look of the digital suits. “So, we introduced more surface texture and played with the materials to get a true metallic response. It was a team effort with Ron Woodall.” Woodall painted, Walker developed materials, and the combination provided a surface that reacted in the way the visual effects supervisors and Favreau wanted when lit. “Most of his armor is a dark, black metal,” Walker says of War Machine. “His face plates and biceps were sort of a brushed aluminum, and we didn’t want the aluminum to pop more than the rest of the armor. Also, he was in a dark environment, so we needed a nice sheen with good edges. We have to do a lot of tweaking to get material to read as raw metal, and paint to read as dull or shiny paint. Ron [Woodall] and I tried to hit the artwork exactly, but in the end, it’s what looks best.”

New shaders that worked with the new energy-conserving lighting technology helped fit the characters into footage shot on location under artificial lighting, and look real in digital environments. “We [created] materials that behaved better, were more energy-conserving, and promised to be easier to use when they got to sequence lighting,” Walker says.

Special settings helped the crew match Iron Man’s look from the first film. Until Terminator, TDs set separate values for specular and reflection. Now, specular and reflection are one and the same; they’re unified and grounded in physics. Even so, some technical directors who had honed their skills using the former methods continued working with the familiar lighting tools. For his part, Snow prefers the new tools and believes they help the lighting artists mature as filmmakers (see “Just Like the Movies,” pg. 18).

“I actually did a shot on this show, a chase scene under the freeway, and it was like lighting a shot on set,” Snow says. “I could go in with a blank slate and create a set of lights from environment spheres shot on set, and put those lights in my scene just like in the real world. Doug [Smythe] has created a suite of plug-ins for managing the new lighting tools that made the process easy; it was very intuitive. You can get something out of the box now that looks real, so you can spend your effort thinking about how a director of photography would approach the shot. It’s not about, Does this suit look like metal? It’s about, How can I approach this creatively?”

On the Ground
In addition to building the digital prosthetics—that is, the parts of the suit that the actors didn’t wear—the full suits, and the drones, ILM created huge environments in which much of the action takes place. In the film, Tony Stark rebuilds the Stark Expo that his father had created as a modern-day technology expo. In reality, the action takes place in New York City on the site of the 1964 World’s Fair, which is now a park. Whenever possible, ILM started with helicopter plates of that site shot by Sirrs, and then replaced everything except the freeways and the Unisphere, one of the few World’s Fair buildings still there. ILM constructed all the other buildings seen in the film as well as the grounds. The challenges were creative and technical.

“Mike Riva, the production designer, had created the expo design, but Jon [Favreau] didn’t ever quite say, ‘This is it,’ ” Snow says. “So, when location photography ended and we had to build the site in postproduction, we asked Jon to articulate what he didn’t like.” Favreau told them that he felt the art was too Blade Runner- and Minority Report-ish. More importantly, he told them that he had grown up in Queens, across the road from the site.

“We thought that maybe he was trying to imagine what this fair was like in his youth,” Snow says. “And if you think of his style, it’s kind of retro. So, we used the 1964 World’s Fair as the departure point. We tried to capture the essence of that and update it, and it was a win.”

The crew found a world of reference on the Internet and even discovered plans for buildings that had been impossible to build at the time. With the creative challenge tackled, the task of actually building the digital Stark Expo fell to the crew at ILM Singapore. “They worked largely in [Autodesk’s] 3ds Max,” Snow says. “But we also mixed in some of our Zenviro tools for certain fast-moving scenes because we like the motion blur better, and CG water that we created in [Pixar’s] RenderMan.”

Much of the action starts in a Japanese garden in the Stark Expo site. Although Fav­reau wasn’t sure he wanted a set built, Snow and Sirrs convinced him that it would help pin down the action. Everything beyond a 20-foot area, though, is CG.

The sequence ramps up with the drones chasing Tony Stark in his Iron Man suit. Once in the Japanese garden, War Machine, Tony’s friend Rhodey, helps him fight the drones. The garden fills with gunfire, sparks, explosions, fireworks, and lights. After several minutes of shooting, Stark tells War Machine to duck. He pulls out new lasers, spins around, and slices the drones in half. And then, with the drones split in half, Whiplash shows up.

“So that gave us the ability to use some of those lighting tools I was touting earlier,” Snow laughs. “We used the whips, explosions, gunfire, all of that sort to make something a little more edgy and atmospheric.”

Marc Chu, who was an associate animation supervisor on the first film, led the animation team who created the characters’ performances for this sequence and the others. “It was a big challenge to make all the characters feel unique,” he says. “Iron Man is nimble. War Machine is less nimble. And the drones were like muscle cars.”

Although Cheadle and Downey wore Imocap suits fitted with chest plates to capture the light, it wasn’t always possible to rely on the captured data for the performances—the super­hero suits have a more heroic build than the actors, and the performances needed to be more dramatic, as well. To choreograph the fighting, the animators motion-captured themselves fighting on ILM’s stage. They could see the action applied to characters in a virtual set, film it with a virtual camera, and then show it to Snow for approval.

“It was fun for the animators to act the shots out themselves,” Chu says. “They weren’t getting data handed to them. It was their own data. They were War Machine, Iron Man, and Whiplash.”

War Machine powers through the climactic battle using weapons added to what was once a silver Mark II Iron Man suit. To light the suit in this shot and others, ILM developed new tools and RenderMan shaders to take advantage of the studio’s new energy-conserving lighting algorithms.

Everything and . . .
When the animators finished a performance, the shots often moved to Timothy Brakensiek in the creature-development department for rigid-body simulation and other effects, and then back to Holcomb. “We wanted the damage to look realistic,” Snow says. “We wanted to rip up the metal and see it bend and flare open. We built entire interiors so when we chop the drones apart, we can see inside, and we hand-modeled the peeling open. It was a cottage industry.”

Holcomb, Garcia, painter Jean Bolte, and Woodall created the suit damage, with Walker managing the levels of damage in the shaders. To slice the drones, they used two versions of one model: one for above and one for below. Shaders drove the slicing; Smythe revised a technique similar to one he had used to decapitate C-3P0 in the droid factory in Star Wars: Episode II, and suck pit droids into engine parts during a pod race.

“We make the part that’s cut off invisible, then add the displacement that distorts the shape right at the edge,” Smythe explains. “Then we put the opposite of that on the other piece and make the other half invisible. That way we could have the top half fall off while the bottom stands there.”

Woodall and Holcomb are especially proud of the damaged goods they created for this show. “We tried to make it look like the damage on automobiles,” Holcomb says. “Sometimes we’ve gone in with only a couple days left to make a bend look better.”

Woodall adds, “It’s something we’re always chasing. You always want to do better in the next film. Things don’t happen for real in CG. You have to make them look like they’re real.”

Surprisingly, though, the two describe something quite ordinary as their most difficult challenge. They built suits for superheroes, working weapons, and military drones. They even created the interior of a C-17 for this film. They built everything, but the hardest asset was the kitchen sink. During a sequence early in the film, Tony Stark gets drunk at a party in his house and puts on his Iron Man suit. Rhodey puts on the silver Mark II and tries to calm Stark down, but Stark rips the sink out of an island in his kitchen and smashes it into Rhodey. Then he tears the kitchen apart. “We turned the kitchen into a pristine asset and damaged it,” Holcomb says. “It was a difficult process.”

Woodall adds, “A guy in a suit of armor is one thing, and because he’s moving, we don’t fixate on it. But, everyone has seen a kitchen counter. It needs love.”

For the first film, Favreau concentrated on character development. He didn’t sacrifice character development for the sequel, but the action definitely exploded. And when the action explodes on screen, there is an equal and opposite reaction in postproduction. Fortunately, ILM and the other visual effects studios that created the action for the film were up to the challenge.