Issue link: https://digital.copcomm.com/i/10832
VFX ■ ■ ■ ■ 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 fi lm, 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 fi lm, 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 eff ect 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 fi lm, we could pro ject the texture map with a clockwise gradient from black to white straight onto the geom- etry and it took about fi ve seconds.” For the Iron Man Mark IV and VI suits, Holcomb, whose background is in industrial design, modeled in AliasStudio’s curve evalu- ation with B-spline surfacing. “I fi nd 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 defi ne the curve fi rst.” T e drones—one style for each branch of the military—all began with base-level geom- etry that the modelers propagated from one Tony Stark’s rival Justin Hammer (Sam Rockwell) builds robotic drones in the fi lm. ILM put anti- aircraft guns on the backs of the Army drones pictured above, and outfi tted other drones with different weapons that represented the Air Force, Navy, and Marines. model to the next. “Because 70 to 80 percent of the parts were similar, we could immedi- ately start painting,” Woodall says. Each drone, however, sports weapons and a paint job particular to its branch of the mili- tary. Army drones can fi re an anti-aircraft gun carried on their backs. T e Air Force drones fl y at Mach speed. Navy drones shoulder sur- face-to-air rockets. And the Marine drone, the only one with a camoufl age paint job, just looks tough. “T e Marine drones were going to be played as the toughest, but we down- played them to play up Ivan’s super drone,” Woodall says. To build the new War Machine suit, Hol- 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 infor- mation 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 com- puters haven’t been fast enough to process the calculations for fi lm 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—usu- ally the brighter areas—to help speed the calculation time. And, lighters can turn switches on and off during the multi-step pro- cess to trade quality with render time. “There’s a fi ght in Tony Stark’s house in Iron Man 2, in the kitchen and in his personal gym,” Smythe says. “The lighting is comb and co-worker Rene Garcia started with Legacy Eff ects’ digital fi les for the practical suits, and then streamlined the suit and added weapons using concept art created at the stu- dio 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.” harsh, and he has tight spotlights in the ceiling that create bright circles of light on the fl oor.” 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 en- vironment, and the environment affects the character.” For this scene, lighting artists who opted to use the new lighting solu- tion especially benefi ted when a shiny suit fell to the fl oor. “We could compute the illumination on the fl oor as indirect lighting using color bleeding [as before], or turn the entire fl oor into a light with bright spots where the lights shine down,” Smythe says. “We fi nally 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 refl ection occlusion were great tricks in the day, but we can do better than that now.” –Barbara Robertson May 2010 19