New Integration Framework and Bidirectional Path Tracing Expand Rendering Options

Pixar Animation Studios has announced a "generational shift" in RenderMan, which will debut a new framework, the RenderMan Integrator System (RIS), in the latest version scheduled for release at SIGGRAPH. Pixar described RIS as a "modular rendering architecture" that optimizes lighting simulation and allows new rendering technology to be deployed as Disney develops it — such as the Principled BRDF shader, a physically based shading technique that will be included in the new RenderMan.

Other features to be included in the forthcoming RenderMan release include an advanced Unidirectional Path Tracer and a Bidirectional Path Tracer with Progressive Photon Mapping (sometimes referred to as vertex connection and merging, or VCM), meaning RenderMan will offer the ability to switch rendering modes for different scenes in a single system, the company said.

"For certain types of shots such as exteriors, the unidirectional path tracer excels," Pixar said in an FAQ detailing some of the additions. "However, while [it is] a common method of light transport, path tracing suffers limitations when rendering other types of scenes, such as dimly lit interiors and caustic effects. For cases like this, RenderMan provides another more advanced method of light transport called VCM, which is able to integrate bidirectional path tracing with photon techniques to produce results of higher quality than either method can alone. With RIS, you can choose the most appropriate method of light transport for any given scene."

In a prepared statement, MPC's global head of lighting, David Hirst, offered a testimonial to the capabilities of the new version of RenderMan. "We … were completely blown away by the speed and how interactively we could preview and render these assets," he said. "The RIS based integrator is going to change the way we work with more scalable rendering and faster results."