Blowin' in the wind: animators bring down the house in a television commercial for VISA. (broadcast).

Like the fairy tale characters on which they are based, the three little pigs in PDI/DreamWorks' recent television commercial discover--albeit the hard way--that building a house of straw is not a structurally sound decision. In the whimsical all-computer-generated spot for Visa, which is airing in Latin America, the pigs become wiser as they build houses of straw and then stick, which are blown to the ground by a huffing, puffing wolf. Finally, the trio builds a house of brick, purchased with a VISA card.

Ironically, constructing--and decimating--the 3D model of the straw house proved to be more of a technical feat than creating the house made of bricks. "The straw house had to look realistic," says director Cliff Boule, "and giving the straw the right look and weight when it was blown down by the wolf was extremely difficult to accomplish."

With such an off-told tale, it was important that we create a unique, new look," says Laura Lockwood, a producer for the PDI Commercial Division. To that end, the group created distinctive-looking characters, props, and lush environments using PDI's proprietary tools and technology that had evolved from the feature film Shrek. For the complicated straw-house effects, though, the team used a commercial software product: Alias|Wavefront's Maya.

Initially, effects animator Randy Hammond constructed the straw house with closed-volume shapes that resembled crudely crafted bricks, which he stacked and layered to form the outline for the house. He then filled each closed-volume "brick" with particles, generated with PDI's proprietary software. "I created a data file that told me where each brick was ...