<em>Terminator Salvation</em>: Battle of the Machines

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McG wanted new Terminators that were beefier and more imposing. All images © 2009 by Warner Bros. and courtesy of Industrial Light & Magic.

After ratcheting up hard body surfaces on Transformers [2] and making more finely textured armor for Iron Man [3], Industrial Light & Magic came up with some new shading, lighting and rendering tricks for Warner Bros.' Terminator Salvation, which introduces a gritty, post-apocalyptic twist from director McG to the famed franchise.

Overall, ILM supplied 366 shots out of 1,300, with assistance from Asylum [4] (including facial replacement for Sam Worthington's Marcus Wright), Rising Sun Pictures [5] (including CG Hunter-Killer explosions and underwater submarine work) and matte paintings from Matte World Digital [4]. Charles Gibson served as overall visual effects supervisor.

"I'm worried that I'm painting myself into a corner with these robot movies," chuckles Ben Snow [6], ILM's visual effects supervisor, who also worked on Iron Man and is now in the thick of it on Iron Man 2. "But we're able to mix up techniques, which is always good. McG definitely wanted to create something new. The Terminator franchise is beloved and always fun to work on. I think there was a little bit of a conscious effort [from everyone] to live up to the legacy of the earlier films in terms of spectacle and effects and to also explore this post-apocalyptic world for the first time. And to build on the idea that no one is safe from these machines -- they're relentless. You can be in the water, the sky, the ground and they're going to get you."

Indeed, according to Snow, McG not only looked to the Terminator films for inspiration, but also Mad Max, Children of Men [7] and Cormac McCarthy's novel, The Road, which has been adapted by director John Hillcoat for an Oct. 16 release.

"On this film, there was a very harsh look," Snow continues, "and what's interesting is that it can be hard on the CG, particularly with the integration issues because they're taking the dynamic range of the film and basically contrasting that up. It tends to throw out the CG a little more easily than if the film was less harshly processed. With that in mind, and because we knew that we'd be shooting in harsh desert environments as well as in the factory [at the end], which is very dynamic, we knew we needed some new materials.

Essentially, what we did was integrate an energy conserving shader set in RenderMan and used that with a higher dynamic range image-based lighting approach to get rendered images that had more of the dynamic range of the original film [that was shot]. I'm definitely glad we did that and we'll certainly be using it all the time from now on. It's not super fast to render, but it'll get faster as we optimize. But it did mean that we were more accurately modeling the physical reality of shining light on metallic objects. I think it enabled us to get more believable real world materials."

Philippe Rebours, ILM digital production supervisor, adds that this new shader system helped put their tools more in sync. "Before, let's say that you have an environment and you want to reflect [your objects]. So in the shader you would use the ray trace function that hits the geometry and that gives you a color or value. But when you use the light, you create a light shader, which is a spotlight or area light, and so the material shader will call that shader and that will give you another value. So there was a difference between diffused and ambience, the same way there's a difference between specular and reflection. However, in real life, specular is reflection. And so we decided to recombine everything in a real world way, which would give you the same result and be more accurate."

For example, when John Connor (Christian Bale) fights a T-600 outdoors in the beginning, ILM noticed that the crew used a big diffuser in front of the sun to make it harsher. This was part of McG's desaturated look (with the help of a bleach bypass DI treatment). So when Rebours and his colleagues did the lighting, they recreated the same look in CG. "We had environment lights and we had an area light to represent the sun that had the same size as their diffuser. And we got something that looked very realistic, very quickly. And in some cases, when it's not a close-up, you definitely have the T-600 in contact with the ground. We textured the ground and there was no difference texturally in the way the ground would bounce and reflect with real light. In previous movies, in our previous set of shaders, we could have a very complex specular highlight because we would use multiple levels of speculars and different colors. However, the reflection [that we got] using the reflection [mode] wasn't as complex, so you had a mismatch of complexity in your material. But now we have the same complexity for everything. The same goes for interiors as well."

There's also a liquid throwback to the second Terminator film: The molten metal required a revamp of fluid simulation tools. "Pouring metal on the [T-800] meant that it had to be more precise and make it look like glowing metal," Snow explains. "But some of subtleties of that are lost on the high-contrast treatment of the film. It was more extreme than we had imagined. But to protect ourselves from what we knew was coming, we developed a DI proxy: A high-contrast and desaturation so we would be looking at that on the side. The Terminator factory was a rich environment and so we developed new tools to light that: we took high- dynamic range images, but they weren't moving because of all the sparks going off. But using this approach, you could put a card with filmed elements with sparks on it or take footage from the background and it became a totally correct light source, so we were able to set up a bunch of these little cards and orchestrate them using some software that Pat Conran, our CG supervisor, developed called Layer Cake, [a GL preview], which allowed us to quickly put in spark elements, which then allowed the TDs to be able to dial in something very quickly that matched the complexity of what was going on in the background. We were free to take the classic endoskeleton fight and make it something very modern.

When it came to building the new Terminators, McG definitely wanted them to look and feel more imposing. They include the Harvester, a giant insect-like machine with multiple arms and legs that collects humans; the massive, aerial Hunter-Killers; the sleek, two-wheeled Moto-Terminators (inspired by the Ducati); and the underwater Hydrobot. There are also redesigns for the T-600 and T-800 (originally designed by Stan Winston for the first Terminator). In fact, there is an encounter with the T-800 prototype in the factory utilizing scans of Arnold Schwarzenegger from the original film, according to McG, which ILM then made more photorealistic by creating a new code (as reported by Bob Strauss of the Los Angeles Daily News).

"We created this giant Harvester device, which was McG's robot monster," Snow recalls. "It's got a great visceral reaction, but if [I] were to sit down and decide how I would design a machine to catch humans, I'm not sure that [this] would be my design. But it was great for ILM. We were able to enhance [the original] designs and to take it somewhere different after Transformers and Iron Man."

According to Marc Chu [10], ILM animation supervisor, "it was fun doing humanoid animation with the endoskeleton, the digital double and then going onto the bigger Terminators. We actually keyframed around 95% [in Maya]. But we also used IMocap [11] technology for the stunt guys to get the interaction with the actors. IMocap continues to evolve; there are less cameras for even a smaller footprint on set. It's very unobtrusive and refined to the point where we can use one witness camera, if necessary. Designers, modelers and creature dev people stepped it up and did a lot of concept work and 3D modeling and teching it out to make every creature in your face, which is what McG wanted."

Snow says the great thing about pushing these more physically-based and image-based tools is that "it gives you more time to spend on the aesthetic side of the lighting rather than just trying to get an image that looks real. It enabled us to provide the right mood. We're moving past the struggle against it looking CG. We're moving to the point where we can have some fun with it. I feel we need to get our speed up a little bit so we can exploit that [more in the future]."

Bill Desowitz is senior editor of AWN & VFXWorld.