THE GOBLET OF FIRE introduces a new method of transport to the series, the Portkey. The Portkey used by Harry and the Weasleys looks just like a battered old boot, but upon touching it transports them to the Quidditch World Cup. Double Negative’s job was to design the visual representation of the journey, with early concepts featuring wormholes and inverted tornadoes. “We wanted to take the audience on a ride — and to convey a real sense of turbulence so they lose touch with reality and what’s up and down,” suggested Michaels. “After experimenting with particle passes and fluid dynamics we settled on a vortex where the world dissolves around the characters as a new location appears around them.” To achieve this the team used proprietary stitching software Stig to create a giant panoramic matte painting of the original location of Stoatshead Hill in England, and in-house tools that procedurally build geometry from match move tracking markers. Senior matte painter Dimitri Delacovias gave further detail to the landscape in Photoshop. Lead 3D artist Ryan Cook then transformed it into a swirling mass of particles that lead compositor Andy Lockley blended together in Shake, while technology originally created for BATMAN BEGINS was used to create digital doubles of the cast to complete the scene.

Since its formation in 1998, Double Negative (www.dneg.com) has firmly established itself as a leading player in visual effects production worldwide. Located in the heart of London’s Soho, the company is a pre-eminent visual effects studio with more than 30 feature films to its credit.