A hallmark capability that defines a renderer as a production renderer is the ability to scale to handle scenes with extreme complexity, including complex illumination cast by a vast number of light sources. In this paper, we present Cache Points, the system used by Disney’s Hyperion Renderer to perform efficient unbiased importance sampling of direct illumination in scenes containing up to millions of light sources. Our cache points system includes a number of novel features. We build a spatial data structure over points that light sampling will occur from instead of over the lights themselves. We do online learning of occlusion and factor this into our importance sampling distribution. We also accelerate sampling in difficult volume scattering cases. Over the past decade, our cache points system has seen extensive production usage on every CG feature film and animated short produced by Walt Disney Animation Studios, enabling artists to design lighting environments without concern for complexity. In this paper, we will survey how the cache points system is built, works, impacts production lighting and artist workflows, and factors into the future of production rendering at Disney Animation.

Achieving a watercolor look was an important goal for the style of Walt Disney Animation Studios’ “Wish”, and screen space textures were critical for achieving this, for example to convey a sense of the watercolor paper texture. However, using traditional screen space textures would have resulted in a distracting shower-door effect where the animation appears to swim through the texture. Our novel dynamic screen space textures overcame this problem by tracking animation and camera movement while maintaining the screen space qualities of the texture.

Null-collision approaches for estimating transmittance and sampling free-flight distances are the current state-of-the-art for unbiased rendering of general heterogeneous participating media. However, null-collision approaches have a strict requirement for specifying a tightly bounding total extinction in order to remain both robust and performant; in practice this requirement restricts the use of null-collision techniques to only participating media where the density of the medium at every possible point in space is known a-priori. In production rendering, a common case is a medium in which density is defined by a black-box procedural function for which a bounding extinction cannot be determined beforehand. Typically in this case, a bounding extinction must be approximated by using an overly loose and therefore computationally inefficient conservative estimate. We present an analysis of how null-collision techniques degrade when a more aggressive initial guess for a bounding extinction underestimates the true maximum density and turns out to be non-bounding. We then build upon this analysis to arrive at two new techniques: first, a practical, efficient, consistent progressive algorithm that allows us to robustly adapt null-collision techniques for use with procedural media with unknown bounding extinctions, and second, a new importance sampling technique that improves ratio-tracking based on zero-variance sampling.

Walt Disney Animation Studios has transitioned to path-traced global illumination as part of a progression of brute-force physically based rendering in the name of artist efficiency. To achieve this without compromising our geometric or shading complexity, we built our Hyperion renderer based on a novel architecture that extracts traversal and shading coherence from large, sorted ray batches. In this article, we describe our architecture and discuss our design decisions. We also explain how we are able to provide artistic control in a physically based renderer, and we demonstrate through case studies how we have benefited from having a proprietary renderer that can evolve with production needs.

With six distinct habitats integrated into one mammalian metropolis, early artwork for Zootopia displayed a large appetite for diverse vegetation. Our flexible toolset for procedural vegetation allowed us to easily customize the system to provide the required variation through new growth and animation module features, while maintaining art-directable control. We enriched the vegetation animation tools and workflows to support various levels of interaction with the characters and environment. To address the geometric complexity produced by all of this variation, we implemented various instancing schemes to allow the renderer to re-use as much geometry as possible.

Look development on Walt Disney's animated feature Tangled called for artists to paint hundreds of organic elements with high-resolution textures on a tight schedule. With our Ptex format [Burley and Lacewell 2008], we had the infrastructure to handle massive textures within our pipeline, but the task of manually painting the patterned textures would still involve tedious effort.

Creating stylized trees with hundreds of thousands of leaves is typically a painstaking task that requires hours of artist time. In Walt Disney's animated feature film Tangled , we faced the challenge of populating dense forests with animated trees on which artists could quickly iterate to meet an art-directed look. We designed a system of authoring trees based around a language of hierarchical curves. Our system lets artists interactively sketch out a base skeleton representation of a tree and grow procedural twigs and leaves out to a canopy shell by tweaking a limited number of parameters.

The first requirement for this work stemmed from the concept art. The director, Mike Gabriel, produced a series of paintings that embodied both the South American feel of the piece and a simple, stylised motif. While each painting contains a relatively small number of brush strokes, each stroke is highly expressive, using a combination of dry and smooth edges to suggest the texture of the underlying subject. Through the early stages of the project it became obvious that neither traditional ink-and-paint animation nor a typical computer-generated approach would preserve the character of the original artwork. Simply put, the primary objective was to keep the final imagery as close to the development art as possible while allowing the animated paintings to move in a coherent manner.