Archive notice: This article was originally published on January 8, 2010. Links and embedded videos are preserved as part of the historical record.
Requirements
Avatar, the groundbreaking stereoscopic 3D film from James Cameron and Twentieth Century Fox, grossed more than USD 77 million on its opening weekend in mid-December 2009. This is the best result ever achieved by a 3D film. Worldwide box-office revenue has now already exceeded USD 1 billion. The science-fiction film is distinguished by its combination of live-action and computer-animated scenes.
New Zealand company Weta Digital played a major role in developing the film’s visual effects. The company has long been an Nvidia customer and uses both Nvidia Quadro and Tesla solutions to create visual effects.
Weta’s task on Avatar was to create sequences with as many as 800 computer-graphics characters. The computing power required was greater than for any previous Weta project. Weta therefore decided to use Nvidia solutions.
“The complexity of Avatar prompted us to rethink rendering,” explains Sebastian Sylwan, Head of Research and Development at Weta. “We use RenderMan for rendering, but given the enormous volumes of data in Avatar, we carried out most of the necessary calculations in a precomputation stage. The task we had to solve was less about rendering than high-performance computing, which is why we chose to use the massively parallel computing power of Nvidia solutions.” Jacopo Pantaleoni, Research Senior Architect at Nvidia, adds: “The central challenge was that, for the first time in the history of computer-graphics visual effects, the required number of polygons was measured not in millions but in billions.”
Solution
The Weta and Nvidia development departments worked together for several months to design ray-tracing software capable of processing the billions of polygons in Avatar.
Nvidia and Weta developed a new precomputation engine called PantaRay, enabling high-performance computing to be used in the VFX pipeline. The name PantaRay alludes to the Greek aphorism “panta rhei,” meaning “everything flows.” The innovative solution enabled Weta to render more complex scenes in less time while using less memory and processor capacity. The result is photorealistic-quality imagery that had previously been impossible for reasons of time and cost.
NVIDIA also ported the PantaRay engine to CUDA-based GPUs. Using a server with an Nvidia Tesla S1070 GPU instead of a CPU-based server enables processing speeds 25 times faster.
Benefits
The advantages of PantaRay are clearly visible in the film’s promotional trailer (under: promotional trailer). The helicopter shots of purple creatures flying over the water with a forested mountain in the background were precomputed with PantaRay in just one and a half days. “With previous methods, this shot would have taken us a week,” emphasises Luca Fascione, Rendering Research Lead at Weta. “We can now produce considerably better shots—you can see exact detail on every bush or individual leaf. PantaRay’s computing power makes the difference.”
Martin Hill, Head of Shading at Weta Digital, explains: “As the complexity of each of our projects increases, so do the rendering requirements. And the more complex the rendering, the more difficult it becomes to make the film scenes clear. With PantaRay, complicated scenes can be calculated just as easily as simple ones.”
For the forthcoming Tintin film project from Steven Spielberg and Peter Jackson, Weta Digital plans to use PantaRay in combination with NVIDIA Tesla GPUs and explore further ways of accelerating visual effects.
A making-of feature on Avatar can be found in the current issue of DIGITAL PRODUCTION, available at newsstands or from the DP Shop.
