Behind the scenes: Iron Man

He’s rich, he’s smart, and he lives in a mansion overlooking Malibu Beach. He even looks like Robert Downey Jr. Tony Stark has everything go...

He’s rich, he’s smart, and he lives in a mansion overlooking Malibu Beach. He even looks like Robert Downey Jr. Tony Stark has everything going for him – except for one tiny problem. There’s something wrong with his heart. Directed by Jon Favreau, Iron Man is the latest in a long line of movies to take Marvel Characters’ comic-book superheroes and transpose them to the big screen. But this time, the superhero in question has particularly human vulnerabilities. Captured by terrorists while showing off a new missile design to the Air Force, billionaire industrialist Stark (Robert Downey Jr) is imprisoned in a cave in Afghanistan. His captors have one demand: that Stark build them a missile of their own. But Stark’s injuries are serious: the shrapnel he took in the chest during the process threatens his heart. Fortunately, he’s a genius.



After fellow prisoner Yinsen (Shaun Toub) fits him with a battery-powered electromagnetic unit that repels the shards away from his heart, Stark uses the workshop tools his captors have provided to build a bulletproof iron suit powered by repulsor technology, and makes good his escape. The events in Afghanistan convince him, once back in America, to build a high-tech version of the costume and use it in the fight against evil. In short, the hero of Iron Man is just a man in a suit. But what a suit.

Although a clutch of leading digital effects studios worked on the movie, Iron Man’s cybernetic costumes actually started life as real hardware. Stan Winston Studio built practical versions of all the suits that Stark wears – the original Mark I, and the successively more sophisticated Mark II and III models – in metal and rubber, along with that worn by Iron Man’s nemesis, Iron Monger (Jeff Bridges).

These suits were used during the live shoot, but for the most part, once Iron Man and Iron Monger are seen in motion, the physical props were replaced with digital versions. The Embassy Visual Effects was responsible for the digital version of the Mark I suit, while The Orphanage also contributed key shots, including some with the Mark III.

However, Industrial Light & Magic did the bulk of the heavy lifting, building the Mark II, Mark III, Iron Monger’s suit, digital environments and other effects seen in around 400 shots. One of ILM’s first and biggest challenges was convincing Favreau that it could create a believable suit. It wasn’t enough that ILM had proven its hard-surface mettle with Transformers’ robots, for which it had received an Oscar nomination: Iron Man placed new demands on the studio.

“The designs needed to be believable,” says digital model supervisor Bruce Holcomb, who moved onto Iron Man from Transformers. “For Transformers, we constructed alien robots with lots of parts doing lots of things and the visual confusion added to the enjoyment. Iron Man was more about design. There are a lot of moving parts [in the suits], but they aren’t ambiguous parts moving for no reason.”

Mixing and matching
Even more importantly, the suits needed to be absolutely accurate. In shots where Stark’s Iron Man suit fully encloses him, the costume is fully computer-generated. But in many shots, he only wears pieces of the suit. Sometimes those pieces are digital; sometimes, they’re practical. Therefore, the digital suits needed to match the Stan Winston models precisely.

For example, when we first see Stark in his workshop tinkering with a boot, the boot starts out as a practical prop, but is backed up by ILM’s tricked-out digital replica. Because the practical boot didn’t have any plates, to give the impression it could hold thrusters that would power Iron Man into the air, modellers at ILM added those details to a digital version they built from the practical model. “Whenever we needed something to fold out, we needed CG,” comments visual effects supervisor Ben Snow.

The suit pieces are also CG when the props were too restricting or uncomfortable for Downey Jr to wear. For example, in a shot when Stark tests his new boots, the gauntlet on one arm is real, but the gauntlet on the arm at screen right is CG. “He couldn’t bend his arm in the practical suit,” says Snow. Nor could he run in it, so while Downey sometimes wore the practical upper chest and arms, Iron Man’s legs were always CG, using a model scaled down from the version ILM had built to fit stunt double Oakley Lehman.

In fact, as shooting continued, Downey wore the suit less and less often, to the crew’s chagrin. “If we could get shots in camera, we could save on VFX shots,” says Snow. “But when he realised we could match the practical suit, he started pulling off pieces of the suit.”

Believable metal
Matching the digital and practical components of the Mark II suit was a high point for the crew. Stan Winston Studio had built the practical Mark II using a silvery brushed metal: a surface ILM hadn’t dealt with for Transformers, and one of the most difficult to achieve with computer graphics. Brushed metal is both highly reflective and highly anisotropic – that is, its reflective properties depend on the angle from which it is viewed – thanks to the numerous minute grooves in its surface. “Brushed metal reflects light in a particular way,” says Snow. “We sent a chip to Russia to get the BRDF [Bidirectional Reflectance Distribution Function], but it was too complex for them to model. So [ILM’s] Doug Smythe and Pat Myers did it with brute force.”

That brute force solution wound through between 5,000 and 6,000 lines of RenderMan shader code to handle specular highlights, reflections and shadows. The trick, however, was in using texture maps to control local parameters and modulate functions. The result was so good that the suit holds up in tight close-ups. “It was our biggest technical challenge, but we made the CG suit look better than the real suit,” says Smythe.

In fact, the CG suit even fooled Favreau and others at the studio. Snow was finally convinced that ILM had succeeded when Favreau called to tell him about a shot that the studio thought looked too fake. “It finally sunk in that they were talking about a shot with the practical suit,” says Snow. “[After that], we started replacing parts bit by bit, and the client started forgetting which were which.”

Fitting the CG replacement parts onto Downey’s body also meant that ILM had to match Downey’s movements exactly. For this, ILM used an updated version of its Imocap performance-capture system, first developed for use on Pirates of the Caribbean: Dead Man’s Chest. Once Iron Man is fully suited up, though, the suit effectively becomes the character and Iron Man learns how to fly.




The movie takes flight
“Flying proved surprisingly challenging,” says animation supervisor Hal Hickel. “We’ve seen a lot of characters fly, but we didn’t want Iron Man to fly like Superman with his fists out in front, or like Peter Pan. We used stills from the comics for reference.”

During his first flight, Iron Man zooms too high and the Mark II suit ices up. He crashes through the roof of his house, through a piano, and onto one of the luxury cars in his workshop. That prompts him to design the Mark III. He makes it out of gold, which won’t ice up, and then tones down the gold with red paint.

While the silver suit doesn’t have any on-board weapons, the red-and-gold suit does. To simulate their moving parts – as they had done with Transformers – ILM’s animators worked with dynamic rigs that allowed them to pick any part of the model and pop controls on it. “The gadgets needed to be cool, but also functional,” says Hickel.

ILM art director Aaron McBride, who rolled off the third Pirates film and onto Iron Man, worked on fitting the Mark III with weapons.

“The suit designs had been done by [Marvel comic-book artist] Adi Granov, but I got involved with designing how some of the weapons deploy from his suit and how they discharge,” he says. “Jon Favreau had us balance something that looked fantastic with visual cues to real-world technology in fighter jets and weapons artillery.”

For example, to design Iron Man’s wrist rockets, McBride referenced A-10 Thunderbolt II aircraft (aka ‘Warthogs’), while the suit’s shoulder micromunitions work like .50 calibre armour-piercing rifle fire. The Mark III also has pieces that fan out to act as shields or even brakes, allowing Iron Man to stop in mid air.

For example, for one sequence, Iron Man gets into a dogfight with F-22 fighter jets. In one dramatic shot, he opens his shoulder fins to brake so the jets fly past. With his fins splayed out, he looks like a Samurai warrior.

For those shots, overall visual effects supervisor John Nelson had filmed a choreographed dogfight between two training jets from a Learjet with three cameras mounted on it.“That gave us the best of both worlds,” Snow says. “We got shots of the jets diving through the clouds that we replaced with the F-22s, and we got sun glinting off the plane which was great reference for Iron Man.”

The final battle
In contrast, for the climactic battle between Iron Man and Iron Monger – a key sequence in the movie – the animators and lighters had no real-world reference material. Moreover, Favreau was interested in moving beyond what the pre-viz teams had done. The fight takes place on a freeway near the Stark building as well as in flight. Iron Monger is a mammoth contraption of a suit that the crew pushed around the set with Jeff Bridges inside. For the digital version, Russell Paul did most of the modelling, while creature TD Keiji Yamaguchi – who had previously turned robots into cars in Transformers – handled the rigging and technical animation. To make him fly, the modellers and Yamaguchi transformed Iron Monger’s boots into rocket thrusters.

“The animators had a lot to do to make him fly, although from a modelling standpoint, he was pretty straightforward,” says Holcomb. “He was a big hulking thing, but after going through Transformers, it wasn’t too challenging getting the weight right.”

Similarly, Ron Woodall, who supervised texture painting for Transformers, agrees that compared to the sheer volume of work for the earlier movie, Iron Man was an easier project. “The silver suit was definitely the hardest to do, but Monger and the red suit were fairly straightforward,” he says. “We had far, far, far more parts to deal with in the robots – plus we had a corresponding car for every robot.”

Iron Man was the thirteenth film that Holcomb has worked on at ILM and he says that it was also the most fun. “I appreciated this one the most because there weren’t 40 things to focus on,” he says. “We had only a couple characters to deal with. It was really enjoyable.”

The lower workload also allowed the studio to progress in some new areas as well. The metal shaders they developed for the movie are even more believable than those used for Transformers. Fine-tuning Imocap’s capabilities has expanded the possibilities for the software. The combination of the two – the believable metal shaders and the precision animation matching – opens the doors to interesting ideas for digital costumes. And the willingness of the director to collaborate with the visual effects crew gave the ILM artists an opportunity to share in the storytelling in ways often not made possible on modern film projects.

In the end, though, was ILM able to convince Favreau to trust computer graphics? The answer, emphatically, is yes. “Jon was very gracious,” says Ben Snow. “He came to ILM and said, ‘It’s no secret that I dislike CG, but I’ve seen what you do and I’m a convert.’”

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