Fancy footwork
Issue: Volume: 27 Issue: 6 (June 2004)

Fancy footwork

Two mechanical crustaceans—as well as the digital artists who created them—recently proved their mettle on an unusual field of play.

In a 30-second nationwide TV commercial, two robotic street crabs—both sporting Nike's new hard-surface soccer boot—demonstrated some fancy footwork while engaging in a rough-and-tumble game of football, as soccer is often called. While this match was entirely virtual, the challenge that it presented to the artists at The Embassy Visual Effects boutique in Vancouver, Canada, was entirely real.

Delivered in less than a month, the commercial features a blend of live action and computer-generated imagery, including detailed character animation, dynamics, and photorealistic rendering. The spot, directed by The Embassy's Neill Blomkamp, was originally intended to feature a beach setting. However, after conferring with Nike's international ad agency, the group opted for a South American urban set instead, despite the fact that the live-action back plate was filmed in Alameda, California.

The spot opens with a shot of an abandoned warehouse lot littered with debris. On the dusty, barren ground, a manhole cover slides open, and out crawls a giant robotic crab, with each of its six legs clad in the new soccer boot. Soon another crab arrives, this one dribbling a large soccer ball. The two face off, aggressively kicking the ball back and forth, using an old bookcase as a makeshift goal. After one of them scores, the camera pulls back, and the term "NIKELAB.COM" appears.
Digital artists put their best feet forward when animating these soccer-playing robot crabs for a recent Nike shoes commercial.

Surprisingly, very little work had to be done to prepare the live-action set. According to The Embassy president Winston Helgason, the desolate location was suggested by someone at the studio who had discovered it while working on a film project nearby. After rearranging a small amount of debris, Blomkamp spent two days shooting the background plates "guerrilla style" using a Canon GL2 DV for a handheld camera look.

"I wanted you to feel like you were right there watching these things play soccer, and have it be totally convincing," explains Blomkamp. "And nothing does that better than filming it like a tourist holding a consumer-level DV camera."

Before filming the backgrounds, Blomkamp created a basic design for the crabs. After receiving approval, he and modeler/animator Dan Dixon constructed the highly detailed creatures using NewTek's LightWave. For the animation, they created a rough animation block that reflected the desired motion—delicate crab-like movements coupled with precise, robotic action—and set up the animation rig to reflect their vision.

Next, the team created the bone structure and the weight maps in LightWave, and then animated the models with a simple IK rig before adding the geometry back in.

All told, the crabs contain some 250,000 polygons apiece, so that in the close-ups, the models stand up—especially in shots showcasing the legs as they swivel, shuffle, and kick with robotic precision.

Textured with Adobe's Photoshop, the models were later rendered using the native LightWave renderer running on generic PCs with dual Intel Xeon processors, the same hardware used for the content creation. The workstations were also equipped with Nvidia's Quadro4 750 XGL graphics cards.

In addition to the crabs, a number of other CG objects appeared in the scene, including the shoes, the soccer ball, a dumpster, light boxes, the manhole cover, and the empty bookcase. To ensure that the shoes—the main focus of the spot—were modeled accurately, Nike sent the artists a prototype, which they used as a reference while crafting the virtual pairs by hand in LightWave. Near the end of the commercial, for the shot in which a crab kicks the ball into the bookcase and knocks it over, the artists used Impact, a simulation tool from Dynamic Realities, for accurate physics calculations.

Next, the group seamlessly incorporated the multiple CG elements into each of the 15 effects shots in the commercial using 2d3's Boujou automated tracking software. Altogether, the artists tracked more than 100 frames for the project. The group later composited the imagery using Apple's Shake. Editing was accomplished in Apple's Final Cut Pro, where the footage was treated with filters to give it a washed-out, yellowish tint to create the feel of a sunny South American city.

Despite the unrealistic nature of the spot, the mechanical crabs blended perfectly into the live-action environments thanks to detailed modeling and animation, giving the commercial an extra kick.

Karen Moltenbrey is a senior technical editor at Computer Graphics World.

Dynamic Realities