Issue link: https://digital.copcomm.com/i/110536
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 ���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 ���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 e���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 ���lm, we could project the texture map with a clockwise gradient from black to white straight onto the geometry and it took about ���ve 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 ���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 de���ne the curve ���rst.��� The drones���one style for each branch of the military���all began with base-level geometry that the modelers propagated from one ��� ��� ��� ��� Tony Stark���s rival Justin Hammer (Sam Rockwell) builds robotic drones in the ���lm. ILM put antiaircraft guns on the backs of the Army drones pictured above, and out���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 immediately start painting,��� Woodall says. Each drone, however, sports weapons and a paint job particular to its branch of the military. Army drones can ���re an anti-aircraft gun carried on their backs. The Air Force drones ���y at Mach speed. Navy drones shoulder surface-to-air rockets. And the Marine drone, the only one with a camou���age 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. 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 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 ���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���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 ���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 E���ects��� digital ���les 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.��� harsh, and he has tight spotlights in the ceiling that create bright circles of light on the ���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 environment, and the environment affects the character.��� For this scene, lighting artists who opted to use the new lighting solution especially bene���ted when a shiny suit fell to the ���oor. ���We could compute the illumination on the ���oor as indirect lighting using color bleeding [as before], or turn the entire ���oor into a light with bright spots where the lights shine down,��� Smythe says. ���We ���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 re���ection occlusion were great tricks in the day, but we can do better than that now.��� ���Barbara Robertson May 2010 19