This was performed by Image Metrics in LA, utilizing its proprietary rigging and animation technology to provide 128 seconds of facial animation. Using a rig that controlled the cheeks, eyes, eyebrows and massive forehead, five animators and four trackers from Image Metrics completed a first pass of animation for the young character. Many shots were then altered in art direction from the original timings to achieve director Natali's vision. Core then imported the data into Houdini and applied it directly to the CG eyes.

Then, as Dren evolves, she becomes more predatory, with the eyes moving more toward the head. "We didn't want to go through the expense of a complete CG rendered head with Delphine because of the number of shots where she's on screen," Munroe says. "Terry and John Mariella, one of our animation directors, came up with a technique that was absolutely brilliant in its simplicity: We brought a company in from Ottawa called XYX RGB and they scanned Delphine's head in very high-resolution detail, so we had a CG data set of her head. On set every day, we put tracking markers around Delphine's eyes to make it easier later on. Once we were finished and got the plates, Paul Waggoner, our head of tracking, then processed that footage and that would go to our compositing team, and they would remove the dots. Then our animation team took that 3D data set of Delphine's head and placed it into the shot so that it was tracked in perfectly, and then the cleaned up version of the plate was camera projected right back on that 3D head; and in realtime, Vincenzo and I could sit with Paul to [determine where to position the eyes]. Then it would be put in the render queue. There was no ray tracing or global illumination or subsurface scattering or ambient occlusion because the lighting was already in the footage. At that point, there might be some cleaning up of the edges by the compositing team. And that was our adult Dren. It was remarkably simple, effective and cost-efficient.

The final problem was Dren's wings, especially the retraction, which wasn't tagged until the final day of visual effects production. "We decided that they needed to desiccate in a way that made sense for the natural ribbing," Munroe adds. "We tried various techniques and finally Terry and his team used the structural lines of the wings to their advantage. They let the wings collapse so that the veins effectively push up against one another and can gather in a much more natural way."

After a sixth-month design/pre-production phase for vfx and 12 months to produce around 500 shots, Munroe singles out producer Steven Hoban. "He convinced Gaumont and the other financiers that this was critical to the success of the film. If the effects were substandard, it would've taken you out of the movie. He gave us the time to figure them out because on a more typical production schedule I don't think we would've succeeded the way we did."

Bill Desowitz is senior editor of AWN & VFXWorld.