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Technology n n n n film. Instead, Lamorlette, who was head of ef- fects for Shrek 2, and Tabellion, who was on the R&D staff, decided to apply what they had learned to the sequel. “Our technique was OK for two shots in a live-action film, but for a full CG movie, it was too slow,” Lamorlette says. “Juan Buhler [ef- fects lead] had been working on illumination techniques using point cloud particles to cre- ate fast subsurface scattering, so we thought, Why not use it for global illumination? It was great; using particles increased the speed tre- mendously.” But, the pair decided to move in a different direction: to bake textures rather than use par- ticles. “We were using NURBS, so it was easy to go from textures to parametric space,” Lam- orlette says. “We had a whole pipeline already for filtering textures and removing noise. So by using textures rather than particles, suddenly the whole pipeline with texture was available. It was more stable than using point clouds, we could do less computation, and it was usable by people well inserted in the pipeline.” Also speeding the computation was a deci- sion by Tabellion and Lamorlette to reduce the number of times they’d send rays into the environment. “We did a lot of tests and discov- ered that with just one bounce, which is called color bleeding, the quality was tremendous,” Lamorlette says. “Having two bounces added maybe five percent more. So, we decided to keep just one bounce and not pay the price for a small gain in quality.” Te first film lit at PDI/DreamWorks us- ing the technique was Shrek 2, which released in 2004. Tabellion claims it was the first big deployment of global illumination in a fea- ture-length animated film. “We used it for characters, which were in 80 percent of the movie, and for maybe 30 percent of the envi- ronments,” he says. “We raised the bar visually because we could light the film differently.” Te studio has used it for every film since. “It’s become a de facto technique for lighting the movies,” Tabellion says. “It keeps the shot complexity down in terms of light rigging.” In 2004, Tabellion and Lamorlette pub- lished a SIGGRAPH paper titled “An Ap- proximate Global Illumination System for Computer Generated Films,” describ- ing their “efficient raytracing strategy and its integration with a micro-polygon based scan-line renderer supporting displace- ment mapping and programmable shaders.” Tabellion singles out the five main innova- tions: irradiance caching, which existed, but which they perfected and modified; raytracing optimization through the use of two levels of detail—low-resolution geometry for raytrac- ing indirect illumination, and full geometry for final rendering; pre-computing and then baking direct illumination and diffuse shading into texture maps, which sped rendering by a factor of 10; using a one-bounce light shader and bounce-filter light shaders that could con- trol global illumination in specific regions, which made the technique art-directable; and lastly, a new approximate lighting model that made it possible to apply irradiance caching on shiny materials. Since 2004, Tabellion has made one sig- nificant change: a way to improve irradiance And More… In addition to these inventors, the Academy gave Technical Achievement Awards to sev- eral people who created render queue systems: Greg Ercolano for the design and engineering of a series of software systems culminating in the Rush render queue management system; David M. Laur for the development of the Alfred render queue management system; Chris Allen, Gautham Krishnamurti, Mark A. Brown, and Lance Kimes for the develop- ment of Queue, a robust, scalable approach to render queue management; and Florian Kainz for the design and development of the robust, The character Hiccup (above), from How To Train Your Dragon, owes the soft lighting on his cheeks to technology developed at PDI/DreamWorks by Arnauld Lamorlette (at right, top) and Eric Tabellion (at right, bottom), for which they received a Technical Achievement Award. caching for surfaces that are displacement maps. “Other than that, the technique is as it was in the early days,” he says. “We’ve looked at other lighting models, but the people are comfortable with this, and they’re perfecting the technique. I can see that the scenes are better balanced. In the early days, there was a tendency to add traditional lights. Now, the artists are dealing only with global illumina- tion, and it shows. So, I’ve been working on other topics.” For his part, Lamorlette, co-founder and CTO at Te Bakery in Gemenos, France, is working on a suite of lighting tools that the company plans to launch by the end of the first quarter. Te suite includes an interactive lighting application, a rendering engine, and tools for managing the lighting process. “It’s a new way to approach lighting and re-light- ing,” Lamorlette says. “We’re using new global illumination techniques and caching as much as possible. It’s a simple approach, but the technology is not simple: Te more you work on an image, the faster it is. We think it will transform the rendering and lighting process of feature films and TV.” highly scalable distributed architecture of the ObaQ render queue management system. In 2000, of the 19 science and technology awards, three were given to people working with computer graphics, including an Award of Merit to Rob Cook, Loren Carpenter, and Ed Catmull for inventing RenderMan; a Technical Achievement Award to George Borshukov, Kim Libreri, and Dan Piponi for what has become known as the Bullet-time technique; and another Achievement Award to Venkat Krishnamurthy for creating Para- form software to automatically convert data from scanned physical models into 3D com- puter graphics models. Tis year shows just how much the in- dustry has changed and how important computer graphics is to filmmaking to- day: All the awards but three centered on computer graphics. We can expect that trend to continue as CG technol- ogy and techniques evolve in the future. n Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net. January/February 2011 21