August 2014

SIGGRAPH 2014

Dane Aleksander—creature effects artist in… Vancouver, British Columbia.

An advance in technology. Software tools are designed and developed for artists to explore their creativity. The art goes too far, and the technology breaks. An advance in technology.

“Parallelization”

We live in a time where computer-graphics lend creative freedom to the visual development industry. As artists have explored and exhausted countless versions of software and hardware in a history of workstations, we too continue to develop our workflow for more creative iteration. At SIGGRAPH, advances in CPU and GPU technology showcased an influence on the animation and VFX pipeline, and the mentality; redesign with parallelism in mind.

Dreamworks Animation, Rhythm and Hues, and Animal Logic presented technical-directions that have served to optimize their respective animation pipelines. I was most impressed with Guido Zimmerman's step back in production on Dreamworks Animation proprietary software, Premo, to develop a tool to better understand the state of their rig's performance.

The tool measured per-frame evaluation of a rig, including read-run-write times for each node and visual feedback on dependency ordering within the evaluation of the rig's node hierarchy. Zimmerman could apply the efficiency logic of a critical path to then influence the structure of a rig's node network derived from the more natural, hierarchical representation. Dreamworks proceeded to redesign their rig pipeline with parallelism in mind. By sectioning serial chain evaluations across parallel threads, the animation team saw a 10x performance boost on the full-resolution Toothless character rig by the end of production on Dragons 2. ^[1]

Rhythm and Hues, Animal Logic, and Dreamworks anew continued with presentations on eliminating weight-painting from their respective pipelines while maximizing physically-based, art-directable animation rigs. A commonality was the procedural approach to the development of muscle systems and anatomical libraries. These lay the foundation for tools within which the artist can efficiently assemble a sophisticated starting point for character animation.

Tuesday morning, Double Negative presented a Creature Feature on the VFX of Hercules (2014) with particular focus on their node-based framework for hair simulation and rendering: Furball. While their physical simulation was rooted on select guide hairs in Houdini, D-Neg have developed Furball to enable parallel computation on both the CPU and GPU, specifically for the large network of relatively independent and uniform curve primitives, aka all the hairs. Hybrid CPU and GPU approaches are often limited by inefficiencies in data transfer between the architectures. However, D-Neg designed a dual-implementation for each data object, with the Furball framework handling CPU and GPU conversions. ^[2]

Use of the GPU allowed artists on Hercules to groom the lion in real-time.

Weta, too, showcased their integration of parallelism in a new facial engine software: Swordfish. Its node-based, hierarchical semi-separated (HSS) representation of the scene served to merge additive nodes, minimize the read/write data-flow and stabilize the memory footprint. Character animators at Weta now have access to full-resolution blend-shapes and full characters rigs during crowd simulations, without a data bottleneck.

Walking away from the conference, the inconvenience of proprietary software is more often outweighed by inspiring stories of journeys within the studios. As was Elliot Kotek's belief on storytelling back in his keynote presentation: to tell stories that “take scientific and technical concepts and present them in a way that might be interesting, because relatability is the key to scalability.” ^[3]

Let's close with a thought on animation.

The Computer Animation Festival at SIGGRAPH is two hours of back-to-back animation. Best in show from the past year, and visual effects in feature films play a significant role. While visual effects breakdowns are very cool, they offer a much different aesthetic than the narrative of an animated short. Art-driven and often independent stories stand out to me, personally, and in 2014 in particular the stand-out short film was The Dam Keeper (2014).

Painterly Characters for Animation

In a similar session last year, Pierre Bénard presented a method that allows an artist to paint-over portions of keyframes, and benefit from predicted and bi-directional in-betweens. His paper titled, Stylizing Animation by Example offered a practical, inspirational step forward in maintaining the stylistic continuity of animated, painterly characters. ^[4]

This year, Disney Research came forward with Authoring and Animating Painterly Characters, research and development of paint-over tools integrated earlier on, within the 3D animation pipeline. The timeline in Maya drives temporal keyframes on a proxy mesh, and artists can layer a range of visual styles using brush stokes that loosely bind to the character rig. They proposed an algorithm using per-frame scene variables like rig parameters and lighting information to then interpolate a configuration-space keyframe. It is in this configuration-space that the stroke effects are manipulated. ^[5]

The five-day SIGGRAPH calender is often brimming with concurrent events. Too many good options is a good problem to have though, and with all attendees navigating their select pathway of panels and presentations, the conference allows for a variety of individual takeaways.

My selection of panels unfortunately had me skip over the production session for The Dam Keeper, however the extended trailer played in the Computer Animation Festival. Both the art and narrative displayed wonderful character, and it is clearly an early culmination of the recent innovations in visual styles for painterly character animation with smooth, controllable results. I am perhaps most anticipating the technical papers on non-photorealistic rendering in coming years, and am watching to see their influence on the animation industry.