Generating realistic human hair for "The Matrix Reloaded"

In recent years, there have been a few successful applications of realistic computer generated hair in the entertainment industry. For The Matrix Reloaded we had to face new challenges. First, we had to handle both close ups and scenes with hundreds of human characters with hair. The task was further complicated by the fact that the CG hair needed to exactly match the styling of familiar heroes from the film: Agent Smith and Neo. Also because of the rendering methods we chose for our virtual actors the hair solution needed to work in a ray tracing context with many lights. Our in-house hair styling tool together with some key rendering techniques made it all possible.