Issue: Volume: 24 Issue: 6 (June 2001)

Red-Hot Prototyping

Designers spice up a miniature set by using RP technology to generate physical pepper models

By Chris Tome

What do you get when you incorporate the zest of computer graphics technology with the traditional appeal of stop-animation using practical elements? A spicy new look, which was what the artists at Red Sky achieved while creating a television commercial for the Chili's restaurant chain.

"This was one of those rare occasions when the client just threw a concept at us-in this case, a chili pepper-and said, 'have fun,' " says Matthew Charde, executive producer at Red Sky, who was given complete creative control of the project.

The commercial starts out with a chili pepper dangling from a tree, and as the camera zooms in, the pepper begins to pulse. It eventually morphs into a mushroom butterfly, then flies away with other mushroom butterflies-and lands on top of a sizzling plate of Chili's fajitas. To achieve the effects, the Red Sky filmmakers used replacement animation, a common stop-animation technique typically associated with claymation animation, the kind used in the feature film Chicken Run. However, Charde knew that creating a clay model of the "star" in the commercial, Chili's signature pepper, would not have produced the highlights and textures he sought. Moreover, hand-sculpting the object for each animation frame would have been extremely time-consuming and costly for the client.

To avoid these drawbacks, Red Sky decided to create the physical models using stereo lithography. Head CG animator Evan Olsen began by modeling the chili pepper in Alias|Wavefront's Maya, which ran on an SGI Octane, and matched it to a hand-drawn animation sequence created earlier. This enabled him to digitally create all the necessary models and positions that would be needed for the spot.

Before outputting the models, the artists had to convert the Maya files to a compatible CAD program. For this project, they used autodessys's FormZ running on an NT platform, which enabled them to prepare the data for use in a Z Corp. Z402 rapid-prototyping machine. In all, Charde and his team created nearly 100 physical models, each of which were about five inches tall by two inches wide.
To create a restaurant's branded chili pepper for a TV commercial, artists first made a digital model, then produced a physical model using rapid prototyping. This saved time and gave the pepper an appearance different from that of the other practical

Next, the artists coated the objects with a light coat of Bondo, a paste commonly used in auto-body repair, and sanded the surfaces to give the models a finish smoother than that produced by the stereolithography machine. Then they painted the peppers with an acrylic to achieve the brilliant color sought by Charde.

While the CG team was busy creating the digital peppers, other artists were building the miniature physical set in which the pepper would be filmed. The biggest challenge here involved making leaves for the trees on which the peppers would hang. "We just couldn't get anything that looked good when we tried to created the models," says Charde.

Their eventual solution was to use actual leaves-but this didn't quite get them out of the woods. Because the commercial was shot at Red Sky's Boston facility (formerly known as Olive Jar Studios) during the dead of winter, colorful leaves were scarce, so the group had them shipped from a warmer locale.

Once all the physical props were ready, the team placed them within the miniature set. To ensure that the final stop-animation would be as smooth as possible, the group shot the sequence at 30 frames per second (native to video format) instead of the typical 24, with a 35mm camera. For the stop-motion, the team used a motion-control stand/software from Kuper Controls that ran on a pre-Pentium PC with OS/2, as well as proprietary motion-control software.
The stop-animation commercial was shot on a miniature set using all practical elements. Aside from the chili peppers, whose origins were 3D, the other models, including the mushrooms, were created by hand.

Aside from the peppers, the other set elements, including the mushroom butterflies, were practical models created from foam rubber, papier-mache, and poly urethane. According to Charde, this provided for a real-world, if highly stylized, set. As a result, the subsequent animation would have been incredibly difficult to re-create with 3D software only.

Charde believes there is huge potential for this type of approach to replacement animation, and he speculates that as personal fabrication methodology moves closer to the desktop, animators-both traditional and digital-will increasingly embrace this mixture of conventional and digital techniques.

"We're making the virtual, real," says Charde. "Or is that virtually real?" How ever it is described, the process is adding a new twist to 3D and traditional animation techniques.

Chris Tome is a San Francisco-based artist, editor, and writer. He can be reached at

Maya, Alias |Wavefront

Z402 stereolithography printer,
Z Corp. (