Harry Potter and the Prisoner of Azkaban: ILM uses SOFTIMAGE[R] IXSI[R] to triumph over dementors in Harry Potter and the Prisoner of Azkaban.(Company Profiles)

Given the success of the first two installments of the Harry Potter series, it might seem surprising that the producers decided to change their proven formula for the third film. But that is exactly what they did on several levels of production. First, Chris Columbus stepped aside as director, making way for Alfonso Cuaron, and then, in order to create new and even more spectacular effects, Industrial Light + Magic changed their production pipeline. Given the huge success of Harry Potter and the Prisoner of Azkaban, it is clear that both moves paid off.

The superiority of the third installment in the Harry Potter series owes a great deal to the initially dark and brooding, yet ultimately amusing and uplifting 3D character animations created by the wizards at ILM using SOFTIMAGE|XSI.

According to Paul Kavanagh, Lead Animator on Harry Potter and the Prisoner of Azkaban: "This was really the first show at ILM that went completely with SOFTIMAGE|XSI. All the other recent projects have built their models in SOFTIMAGE|3D and imported them into XSI for the animation tools, but this time we decided to build a pipeline entirely around XSI. It was a bit of risk, but it turned out to be an entirely pleasurable experience."

With their new XSI-based pipeline, the ILM team were ready to take on all the creative challenges that Cuaron sent their way. One of the first such challenges took the form of a giant spider.

"When Ron Weasley (Rupert Grint) encounters a boggart, it takes the form of an immense black widow spider. He is terrified, but, with the help of a Ridikulus charm, he puts the beast on roller skates," says Kavanagh.

The success of the sequence depended on making the spider appear real enough to scare both Weasley and the audience and then ensuring it ...