A Linux-based production pipeline is a perfect choice for a major motion picture like The Spiderwick Chronicles, with its many goblins and magical creatures. Hollywood has been the realm of Linux since 1997, when the movie Titanic proved that Linux can do big computer graphics jobs like rendering a sinking ocean liner. With an industry tradition of using UNIX-based operating systems for high-computation jobs, and due to the better, faster, cheaper nature of Linux, every major effects or animation movie today is produced using Linux. Visual effects facilities ILM and Tippett Studio each created visual effects for Spiderwick. Having multiple effects houses work on the same movie became common after 2003 when The Matrix Reloaded used a dozen effects houses.
The idea of switching Mac desktops to Linux is new in the film industry. The film industry routinely uses Macs running OS X for specialized tasks, such as art department concept artwork generated using Adobe Photoshop, picture editing with Final Cut Pro and sound editing with ProTools. When you scale past a few systems, the advantages of Linux for graphics become apparent, and Linux graphics PC desktops are the norm. The television series South Park is a notable exception, with Mac OS X desktops running Maya with a Linux renderfarm.
During the production of Spiderwick, Tippett Studio switched to Fedora Linux running on Macintosh desktops. “We currently have 119 Intel-based Apple Mac Pro workstations running Linux”, says Tippett Computer Graphics Supervisor Russell Darling. “We decided to go with Apple hardware running Linux for our primary artist workstations on The Spiderwick Chronicles, although it might have been considered a risky endeavor for a show in production. We initially had some problems with sound on Maya and a few other minor issues, but they were resolved. We got a patch from Autodesk that took care of everything.” Commercial Linux software vendors work closely with film studio clients.
Tippett chose Linux on Mac for many reasons. “There’s the ability to run multiple operating systems, including Linux, OS X and Windows”, says Darling, and he continues, “The systems are fast! That makes for more productive artists. The hardware is quiet and energy-efficient. It’s cost-effective, with a good cost per rendermark [a renderfarm performance benchmark]. It’s standardized hardware. And, there’s a good support plan. Although the majority of our workstations run Linux, we have a handful of other systems running to support specific software. We use the ability to boot in to other operating systems, but the ultimate goal is to move to a simultaneous multi-OS solution, such as Parallels.”
To beat traditional alternatives, the Apple Mac Pro workstations had to meet a specific set of Tippett requirements. They had to run Fedora FC4 and XFS. They also had to run tools that Tippett uses, such as Maya with sound and in-house and third-party plugins (MEL scripts), Apple Shake with in-house and third-party plugins, SyFlex, cMuscle, RealFlow, JET, Flipper, rtTools and cineSpace. Internally developed software uses Python, Perl and C/C++. The platform must render frames identical to existing hardware. And, it has to support necessary peripherals, especially tablets.
“The important thing with a fantasy genre is referencing nature”, says ILM Art Director Christian Alzmann. “The Byron plumage is based on a red-tailed hawk. We’re always drawing reference from nature. I did the early design of the Sprites with a bee next to them for scale, with two bees flying in formation. Mulgarath is part man, part bull, part goat, part trees. The warthog is a mean aggressive character, so we got pointy with him. And, he’s a lot more distorted. We also use scale cues, such as a Chiquita banana sticker or Pepsi bottle cap.”
“The Griffin has hair plus feathers and was rendered at 8k [images 8k pixels wide] to get detail”, says ILM Animation Supervisor Tim Harrington. To achieve that level of detail meant 25- to 30-hour renders.
“Spiderwick took 215 artists and 15 months”, says ILM Visual Effects Supervisor Tim Alexander. “It has 341 shots, 30 minutes, with 224 3-D shots.”
Industrial Light & Magic occupies the 865,000 square-foot Letterman Digital Arts Center on the 23-acre San Francisco Presidio campus. Its data network has more than 300 10GB ports and 1,500 1GB ports, with fibre to every artist’s desktop. There are 600 miles of cable throughout the four buildings on the campus. A 13,500 square-foot data center houses a Linux renderfarm with 3,000 AMD processors and more than 100TB of storage. Proprietary render management tools add Linux desktop workstations to the renderfarm pool after hours, expanding the processing capacity to more than 5,000 processors.
As Creature Supervisor for The Spiderwick Chronicles, visual effects pioneer Phil Tippett oversaw the design and development of the film’s fantasy characters. “Phil Tippett was on set with me every day”, says Director Mark Waters. “We were working on Charlotte’s Web when Mark Canton gave us the script”, says Tippett Studio Visual Effects Supervisor Joel Friesch. “When we saw the creatures, we had to do it. It’s based on real creatures, not fantasy. We wanted Hogsqueal. We created a bull goblin marquette [a detailed statuette] that gave Mark something he could hold. The bull goblin is based on toads. We brought in real toads and photographed them. We created movies good for the animators, showing how the eyes move and the throat. We created a test scene with a goblin scratching the back of his leg. That took one month of modeling and one month of animation.”
Figure 1. Tippett Studio’s proprietary Creature Manager is used to maintain a library of creatures and animation cycles. The tool allows an artist to select and preview animation by pressing the larger creature button, then selecting a combination of an appropriate physical appearance for that creature from a predefined library and placing any number of selected creatures into a Maya scene.
Hand animation is a challenging laborious process. “One guy does blocking, like moving chess pieces”, says Tippett Studio Animation Supervisor Todd Labonte. “You get it approved. We watch it over and over. You can go blind. We play it back in mirror image in our player or play it backward.” Labonte demonstrates playing back a scene of goblins invading the house, shown in their Flipper playback software, which can display a mirror image or play in reverse to help catch animation inconsistencies. Flipper is used to view both QuickTime and image frame sequences of DPX, EXR or TIFF with synchronized AIF audio. Flipper predates commercial Linux flipbooks, such as FrameCycler. At older studios, like Tippett, it’s common to find proprietary Linux tools created before commercial options were available. Tippett has a team of eight Linux programmers to maintain and develop tools.
“Creature Picklist is a GUI-based Maya plugin for creatures that allows animators to see visual representations of character, which they can select for their scene”, says Darling. “In the case of Spiderwick, ‘Goblin kits’ were created as combinations of variants and blendshapes. We have shots that have more than 100 goblins. That’s too many to animate using traditional methods. The numbers are also too small to make a commercial crowd system, such as Massive, a viable solution. We developed our own system called Swarm. For the Spiderwick shots, we instanced around 150 goblins and managed animation clip data to animate them as particles.”
Figure 3. Tippett Studio’s Picklist allows an animator to select creature variants from a library of different combinations of paint schemes and body parts.