Along with a slew of VFX breakdown videos and images, ‘Piper’ supervising technical director Brett Levin details the tools and techniques employed on director Alan Barillaro’s Oscar-nominated CG short.
By now, most of the world has already met Piper, the world’s most adorable Sanderling and the star of Pixar’s Annie Award-winning short film that played in theaters ahead of the studio’s Finding Dory feature this past summer. Now, take a look at Presto, one of the in-house tools developed at Pixar in order to bring the photorealistic yet stylized sandpiper to the screen.
Produced by Marc Sondheimer and directed by Alan Barillaro, the supervising animator on Pixar features WALL•E and Brave, the six-minute short follows hungry hatchling Piper, who must overcome her fear of the water in order to eat. An allegory about the way children learn resilience -- from their parents and from each other -- Piper is a story about conquering one’s personal fears.
Taking more than three years to complete, the project began as a series of tests conducted to create more painterly CG animation tools that would allow artists greater flexibility during the design process.
“I was testing a sculpting tool. What I mean by that is computer tools are getting more and more visual. I want to see it go all the way. The computer is just a tool. It does nothing for you until you pick it up and start driving it artistically. To me, everything in computer technology is about giving the artist the same quickness and ability as a pencil. They pick it up and they express themselves as soon as possible. The more the technology is hidden at Pixar, we feel the more expressive the art will be,” Barillaro says of the process. “I grabbed the wise woman’s crow model from the film Brave and started shaping it into a sandpiper. I just did a little test. It was just to say as an artist, ‘That’s how quick it should be. You should be able to shape something really quickly, express yourself, throw it at an idea and not have to go to any other departments.’ That’s how artists should talk to each other visually.”
The resulting tool, which works with a Wacom tablet, was dubbed the Presto Sculpting Brush. It allows 3D artists to apply sculpting shape refinements on top of a posed or un-posed model, using brush controls familiar to any Adobe Photoshop usersuch as radius, strength, falloff and erase. Within Presto, sculpts are set up into layers, so artists can stack together multiple sculpts and mute or enhance them to see their effect. Sculpts sit in a timeline, so they can be animated and blended, and a magic silhouette brush lets users sculpt the model by redrawing regions of the silhouette in order to clean up shapes or achieve lines that the character rig doesn’t provide.
According to Brett Levin, who served as Supervising Technical Director on Piper alongside roughly 90 other artists working on the project, Presto served as a major component of the studio’s technical pipeline. “With experience we found that Presto augments rather than replaces conventional workflows, with each technique having its strengths,” he says. “Conventional rigging is still the best for making a model that can deliver a broad range of performance, but it is a demanding technical discipline of its own. Being able to sculpt and tweak the posed result directly in shots, to camera, has given us a flexibility we’ve never had, letting artists work directly on the image, with techniques familiar to anyone who has used Photoshop.”
Pixar’s Universal Scene Description (USD) anchored the technical pipeline as the common data format. In addition to utilizing Presto for rigging, layout and animation, Pixar artists employed Autodesk Maya and Mudbox for modeling, SideFX Houdini for animated FX, The Foundry’s Katana and Nuke for look-dev and lighting, and the studio’s in-house rendering tool RenderMan for delivering final rendered images.
“The big technical challenge was developing the feathers, sand, water, and foam,” Levin recounts. “We needed ways to animate them without getting overwhelmed, and we wanted to capture their visual details up close.”
That challenge was partially overcome by the close pairing of animators with FX artists. “Our animators used simple rigs and sketches to rough-in the sand and water FX to support the character performances. We handed shots back and forth to develop the temp FX into more detailed elements in tandem with editorial and animation polish. For example: our waves started as a simple familiar spline we had previously used in an eyebrow rig. We covered our beach in those, timed to work with the birds and in the cut, then developed those into solid wave shapes and then a fluid simulation,” Levin details.
“Our visual goal was combining the simplified shading of an illustrated storybook with the sophisticated photographic lighting response can get from a path tracer,” Levin adds. “Technically, we achieved our look goals by studying the fine-scale structure of feathers, sand, and foam and then simplifying them. Our renderer, RenderMan, proved it could gracefully handle millions of feather curves, sand grains, and individual foam bubbles.”
Courtesy of Pixar Animation Studios, here is a video playlist of 11 VFX breakdowns from Piper, including fluid, foam and sand simulations: