Visual effects supervisor Peter Chiang and his team learned the geography of Stardust's world well. All images © Paramount Pictures. Courtesy of Double Negative. 

When he started preparing Stardust (opening Aug. 8, from Paramount), director Matthew Vaughn had just directed Layer Cake, a gritty thriller. He thus went straight from the gloomy world of cocaine dealers to a fantasy world populated by magical characters, all of which requiring hundreds of high-end visual effects. In this adaptation of a novel by Neil Gaiman, a young man named Tristan ventures into a magical land to retrieve a fallen star for his beloved. The quest marks the beginning of a wild adventure filled with pirates, kings, ghosts and witches.

Working with the director to realize the 830 VFX shots was visual effects supervisor Peter Chiang along with vfx producer Tim Field. 350 shots were assigned to Double Negative where digital supervisor Mattias Lindahl oversaw the effort. The remaining shots were spread among six different vendors, including LipSync Post, Cinesite, The Senate, Baseblack, Machine and Rushes. Mattes & Miniatures provided miniatures.

Geography Lessons in CG

For Double Negative, the main challenge laid in the creation of vast environments. "Matthew wanted to join certain scenes to explain the geography of where the story was taking place at every moment," Chiang says. "So, we always shot the front end and the back end of those shots as a live-action plate. We would start with an actor and initiate the camera move on set. Then, we would transition into a camera move over a CG environment, and the shot would end with a live-action plate filmed on another set. By opening and ending a shot with real actors, the scene would be better anchored in reality."

The environments were based on The Isle of Skye in Scotland, and Iceland, where most of the location work took place. A company supplied high resolution digital terrain maps and texture maps of those locations. "The terrain maps didn't come with fine displacement maps, which meant that it only worked from a certain height," Chiang notes. "And the trees lacked foliage. So, we used the maps to generate the basic terrain model with its elevations, and then further developed it with Double Negative's proprietary software Tecto."

Tecto is a landscaping tool that was originally created by Double Negative for the aerial scenes in Flyboys, of which Chiang was also the vfx supervisor. "It allows us to work with huge amounts of image data," Mattias Lindahl says. "The individual tiles where 4k each. Tecto manages all that data for you, only pulling in the bits you need at render time. It also allows you to output low resolution versions that we can work with in animation and previsualization. Most of our shots where high enough off the ground, so we had a good level of detail in the photography." Surrounding the CG terrain was a 3D cyclorama of tall mountains created within Maya. Shots were rendered in RenderMan and composited in Shake.