The visual effects team developed 43 digital infected humans with unique features and costumes, and seamlessly integrated them into scenes with a live actor. 

Crowd Simulation
One of the most challenging part of the Infected assignment was generating up to several hundreds characters at a time, a task for which Imageworks utilized Massive. "We used Massive both for pre-infection crowd shots, and for the larger Infected crowds," Smith notes. "We motion captured many different walk and run cycles that we later modified to create a more fantastic performance. These were Infected, not human beings, which meant we had to slightly alter the body language."

The crowd scenes were rendered using different levels of resolution on the characters. For instance, background characters didn't have any skin translucency -- the team was able to develop a single-layer look that was almost as convincing as the three-layered foreground characters. Lighting was carried out in Imageworks' proprietary Katana, and rendering in RenderMan. The shots were then composited using in-house Bonsaï package.

Imageworks' animation team also created various wild animals roaming through the deserted city. All were generated using keyframe animation, based on reference footage.

A True Performance
"The visual effects team developed 43 digital infected humans with unique features and costumes, and seamlessly integrated them into scenes with a live actor," Berney continues. "The infected had to look real, and be completely believable. In the end, we definitely achieved that and more by creating characters that worked seamlessly in the story and whose performances were both eerie and poignant throughout the film.

Adds Sirrs, "The creature work really pushed the level of photorealistic (humanoid) creatures to a level that I certainly hadn't been involved with before. As part of that process, we had to tackle the challenge of selling believable, nuanced and emotional performances from the creatures. Without that, they would have become simple cartoon monsters and some of the value of the picture would have been lost."

Alain Bielik is the founder and editor of renowned effects magazine S.F.X, published in France since 1991. He also contributes to various French publications, both print and online, and occasionally to Cinefex. In 2004, he organized a major special effects exhibition at the Musee International de la Miniature in Lyon, France.