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■ ■ ■ ■ Trends & Technologies Last month, two weeks before the main event, the Academy of Motion Pictures Arts and Sciences awarded 15 scientifi c and technical awards to 46 men who pioneered advances in moviemaking technology. Among the awards this year was a Scientifi c and Engineering award given to Per Chris- tensen, Michael Bunnell, and Christophe Hery for developing point-based rendering for indirect illumination and ambient occlusion. T e fi rst fi lm to use this rendering technique, Pirates of the Caribbean: Dead Man’s Chest, won an Oscar for the visual eff ects created at Industrial Light & Magic. Now available in Pixar’s Render- Man and widely adopted by visual eff ects studios, the point-cloud rendering technique has helped studios create realistic CG characters, objects, and environments in more than 30 fi lms. Simply put, the technique is a fast, point-based method for computing diff use global illumina- tion (color bleeding). T is point-cloud solution is as much as 10 times faster than raytracing, uses less memory, has no noise, and the amount of time it takes to calculate does not increase when surfaces are displacement-mapped, have complex shaders, or are lit by complex light sources. It owes its existence to a unique interplay between researchers in a hardware company, a software company, and two visual eff ects studios. Bunnell’s Gem of an Idea T e idea originated with Michael Bunnell, now president of Fantasy Lab, a game company he founded. Nvidia had just introduced its programmable graphics processing unit (GPU), and Bunnell was working in the company’s shader compiler group. “It was a new thing and an exciting time,” he says. “We were translating human-written shaders into code that could run directly on the graphics processing chip.” Real-time rendering made possible by the GPU opened the door to more realistic images for interactive games and more iterative shading and lighting in postproduction houses. Bunnell pushed his excitement out into the world by writing a chapter for the fi rst GPU Gems book on shadow mapping and anti-aliasing techniques. “It wasn’t a new technique,” Bunnell says. “It was about doing some- thing on a graphics chip in a reasonable number of steps.” Bunnell was more interested, though, in subdivision surfacing, in tessellation that breaks a curved surface into the triangles needed for rendering, and he began working on ways to render curved surfaces in real time. T e demo group at Nvidia used his code for a product launch, and then asked if he could do some- thing more: real-time ambient occlusion. Ambient occlusion darkens areas on CG objects that we can see, but that light doesn’t reach—the soft shadow 30 March 2010 At top, when Russell holds open Carl Fredricksen’s door with his little foot in Up, he owes the soft, colored shadow beneath to an award-winning point-cloud-based rendering technique. Above, the diffuse, indirect illumination also helps make Carl’s storybook house believable.