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How computer farms create movie special effects

May 21, 1999
Web posted at: 9:23 a.m. EDT (1323 GMT)

by Andy Eddy

Network World Fusion

(IDG) -- In the movie Twister, there's a thrilling scene in which a tornado barrels through a field and smashes a barn into toothpicks as it heads toward a speeding truck carrying the storm chasers.

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Movie makers created this particular bit of magic with special effects and animation. Churning out such high-resolution scenes requires lots of computing power, so computer graphics specialists are turning to distributed computing, or render farms.

Rather than use one computer to generate an image, a render farm spreads the job across several networked computers to speed production. Special software has the intelligence to delegate pieces of the work to available computers, freeing staff members from having to worry about what resources are available.

Cultivating an Antz farm

A render farm was handy for Pacific Data Images (PDI), a visual effects and animation studio that created and co-produced the movie Antz with Dreamworks SKG.

PDI built a large-scale render farm in early 1997 to handle the massive quantity of rendering required for a feature film, according to Mark Kirk, lead technical director for systems at the Palo Alto company.

The render farm contains about 250 Silicon Graphics, Inc. (SGI) Origin 200 workstations, each with dual R10000 Reduced Instruction Set Computing processors, 500M bytes of RAM and 4G bytes of local disk storage. The systems are connected to several large network file system servers over 100M bit/sec Ethernet, although this summer Kirk will be upgrading most connections to Gigabit Ethernet.

PDI developed most of its own computer graphics applications, but the studio relies on Platform Computing's Load Sharing Facility (LSF) to run the show. LSF is a batch-queuing program that divvies up and oversees the rendering jobs.

Kirk says LSF provides flexibility and a high level of automation that helps the firm maximize its computing resources.

"LSF can detect if a machine is idle, and we can set certain thresholds and policies about when and under what circumstances we'll submit jobs to that machine," he says. For example, if someone goes to lunch or heads home at the end of the day, LSF can dynamically add the idle computer's processing power to the render farm.

Generating game graphics

Another company putting a render farm to work is Monolith Productions. The Kirkland, Wash., electronic game publisher uses its farm to generate cut scenes - cinematic animations that connect the playable segments of a game. Monolith also harnesses its render farm's power to more quickly process the complex level maps that create the playfields of its 3-D games.

Monolith uses three Intergraph RenderRAX hardware units, which house a total of 15 rack-mountable computers. Each computer has four Pentium 200 processors and 256M bytes of RAM. The computers are networked via Ethernet and 100M bit/sec ATM. Graphics packages, such as Softimage's Mental Ray and Discreet's 3D StudioMax, distribute the rendering work among the connected systems.

Brian Waite, vice president of 3-D graphic engineering at Monolith, says the render farm has reduced the time it takes to output a graphic frame by up to 80%. That figure varies because Monolith can incorporate idle desktop PCs into the render farm. Waite chose to run the farm on Windows NT so it would be able to interoperate with the firm's Windows 95, 98 and NT desktops.

A starring movie role

Like Monolith, Digital Anvil relies on extra computing muscle to generate cut scenes for its games. Moreover, the production and entertainment firm used the render farm to produce the visual effects for the recent release of Wing Commander, a live action movie based on the game of the same name.

Digital Anvil has adopted a blend of systems to make up its render farm, according to Chris Olivia, visual effects director for the company in Austin, Texas. The render farm includes 450-MHz Windows NT Pentium PCs and high-end Unix workstations, and runs on a switched 100M bit/sec network.

Proprietary software distributes the rendering jobs to idle computers, while Digital Anvil creates the graphics using Alias Wavefront's Maya software suite.

Digital Anvil has had a few problems running multiple platforms in the render farm. The current Maya software doesn't yet provide cross-platform compatibility, so the firm needs to run different versions of the product on its NT and SGI boxes.

"It's kind of a hassle to change back and forth," Olivia says. He's waiting for Maya 2.0 to solve this problem, but for now, his NT boxes lay idle because they only support an older version of the rendering software.

Just the same, Digital Anvil is looking forward to growing its farm with the addition of more NT systems in the near future. The NT boxes provide a cost-effective way to put more processors on the job.

As the price of computers continues to dive and processing speed multiplies by leaps and bounds, render farms will give entertainment companies even more power to construct visions that push the bounds of the viewer's imagination.

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