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DNxHD Marvel

Mar 1, 2008 12:00 PM, By Michael Goldman

Behind the DNxHD 36 workflow for Iron Man.


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<i>Although Stan Winston Studios built three physical suits for Iron Man (played by Robert Downey Jr., pictured here with Director Jon Favreau), Industrial Light & Magic used technology it had developed for </i>Transformers<i> to enhance the suit’s complexity—including the wire-heavy “under-skeleton.”</i>

Although Stan Winston Studios built three physical suits for Iron Man (played by Robert Downey Jr., pictured here with Director Jon Favreau), Industrial Light & Magic used technology it had developed for Transformers to enhance the suit’s complexity—including the wire-heavy “under-skeleton.”

The project was such an early application of the Adrenaline HD system that one of the project's major bugs was related to matching sound to picture during the editorial process. Assistant Editor Dawn King says the editorial team had periodic trouble rebuilding open-media framework (OMF) databases in Adrenaline after receiving production sound on hard drives. They also had problems with audio timecode in the databases dropping out late in takes.

“For the OMF database problem, we used the AIFF audio format for our sound, and when copying media onto our drives, the media would not relink, and the databases would not rebuild properly in the Avid [much of the time],” King says. “The workaround we used was to import the audio media, rather than copying it onto drives. This can be problematic if you want to rename clips, because when you import audio linked to a master clip, the master clip will revert to what it was named when it was digitized. It's not a big issue when you first bring media into the Avid to work with, but if you have to re-import media, it can cause extra work. With the [timecode bug], we had to re-enter the sound timecode in the database for every take in the show.”

An offshoot of the HD editorial process was the fact that it benefited ILM's artists for the massive visual-effects portion of the project, because it allowed the facility to more efficiently search for alternative background plates, run tests, and provide temp effects shots for preview screenings, while significantly reducing the number of filmouts required to accomplish all those things.

Ben Snow, ILM's visual effects supervisor on the project, working in collaboration with Senior Visual Effects Supervisor John Nelson, says he wholeheartedly agrees with Lebental that editing in the DNxHD 36 codec was a major boon to the project, despite the bugs.

“It really changes things,” Snow says. “It's easy to forget that a couple of years ago, we would have had to film out great swatches of unfinished work so they could have temp screenings. This [HD format] gives you a very good looking temp screening that is digitally projected at basically 2K, and that lets you know you are in good shape. We got the same [Adrenaline] Avid system here [at ILM], and yes, there were some bugs, like with any new technology release. We were also limited because we only had one of those systems up and running during production on this movie, instead of several like we had with older Avid systems. But they telecined the entire movie to HD resolution, and that's a big thing. It wasn't quite as high quality as a film scan, but it gave us really good material to work with when seeking alternative background plates and running our tests.”

<i>Although Stan Winston Studios built three physical suits for Iron Man (played by Robert Downey Jr., pictured here with Director Jon Favreau), Industrial Light & Magic used technology it had developed for </i>Transformers<i> to enhance the suit’s complexity—including the wire-heavy “under-skeleton.”</i>

Although Stan Winston Studios built three physical suits for Iron Man (played by Robert Downey Jr., pictured here with Director Jon Favreau), Industrial Light & Magic used technology it had developed for Transformers to enhance the suit’s complexity—including the wire-heavy “under-skeleton.”

Digital costume

Realism was a constant topic of discussion on the visual-effects front, considering there were multiple versions of the Iron Man suit in the movie and each of them had to evoke realistic and heroic movement. In the majority of the shots in the film, the suit was called upon to display fantastical mechanical abilities or movement that simply wasn't possible with Stan Winston Studios' practical suit worn by actor Robert Downey Jr.

Therefore, the team developed a highly sophisticated digital costuming solution. The end result, according to Snow, was the development of digital pieces of costume that evoked a sports-car mindset. “It was fully featured, tricked, and pimped out,” he says with a chuckle. “The actor would wear our specialized mo-cap bands and whatever parts of the suit he could comfortably wear, and then we'd fill in the rest with CG — in most cases, doing almost the entire suit and having it move very exactly on his body.”

ILM took techniques and proprietary tools developed for its inhouse iMocap performance-capture system, enhanced for the last two Pirates of the Caribbean movies, and further advanced them for Iron Man.

Snow says the Iron Man team used iMocap tools on set, but with a lower profile than Pirates — using a single data-capture camera, rather than multiple camera setups. That motion was then pumped into various CG pieces of the Iron Man suit to make it move as Downey Jr. did. Another recent film to pass through ILM, Transformers, directly impacted lighting and texturing — which was based on improved high-dynamic-range-image-based lighting tools and metallic surfaces created for Transformers. The Iron Man team extended those tools to achieve the distinctive red and gold of Iron Man's final suit (dubbed Mark 3) and the brushed-chrome look of the interim silver version (Mark 2). (Early Mark 1 suit shots in the movie were created at Embassy, Vancouver.) Unlike Transformers, the Iron Man suits had to cut directly back and forth with the practical suit, and in many cases, CG suit parts joined with practical suit parts within a given shot.

“That's why it really helped us to have better tools for capturing and seeing the fidelity of the real set,” Snow says. “We can better take high-dynamic-range images and use them to light our work. We developed ambient occlusion and things back when I worked on Pearl Harbor so that we could approximate self-shadowing from environmental lighting. But since then, we have tools to make it possible to do more accurate indirect lighting and self-reflection. On this film, that's important because [Iron Man] wears a metal suit — we could better reproduce the way the metal would reflect itself. If you have shining lights on one surface and those lights bounce to another surface — we can now capture all that with a high-dynamic-range that we can use for lighting our CG object. And instead of faking reflected light with bounce lights, we can calculate them directly. It's very computationally expensive, but we had to ramp up our processor pool [at ILM] to get through Pirates of the Caribbean 3 and Transformers anyway — so we had that available to us.”

Snow says that Favreau wanted the movie to more closely resemble a gritty, realistic war film than a typical superhero movie. Therefore, the practical suit built by the Winston team was used extensively to capture real textures and the foundation of certain plates.

“We also went out and photographed damaged cars and things to reference the suit as it got banged up,” Snow says. “Then, we put layers and layers of texture onto the thing. At one point, there were about 20 layers of maps to create different levels of smudge and damage as [the suit] gets beat up.”

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