There are few certain formulas for Hollywood success, but one of those is:

Will Smith + action-oriented script + visual effects = a great movie-going experience.

This is the plan behind I Am Legend, the post-apocalyptic action-thriller starring Smith as Robert Neville, a brilliant scientist who appears to be the last man on earth. Neville lives in a New York City decimated by a man-made and seemingly incurable plague to which he is somehow immune. Neville is driven to find a way to use his own immunity to reverse the effects of the virus, but he must do it before the mutant victims of the plague—the infected—stop him. Neville is outnumbered and running out of time.

Like any action movie, I Am Legend takes advantage of cutting-edge visual effects techniques like motion capture. Using motion capture to generate realistic movements for animated characters has become a staple of movie production nowadays. Motion capture is a technique to digitally capture the movements of people and objects and then to use them as the basis for animating characters. Motion capture can greatly reduce the time needed to create ultra-realistic movement and by compositing animated characters into live-action shots, filmmakers have greater flexibility in choreographing large-scale action scenes and can depict “stunts” that would be too difficult or dangerous to attempt with live action.

For I Am Legend the motion capture team from Sony Pictures Imageworks tried something different. Instead of working from a detailed shot list to produce specific movements to be used in preplanned shots, the motion capture team focused on developing a library of movements that could be edited, turned into animation, and combined with the live-action shots later in the production.

With only a small crew, the motion capture team spent a lot of effort at the beginning of the production of I Am Legend focused on capturing a variety of character movements, from the run of the mill walking, running, and jumping, to rather extreme stunts like falling over moving cars and being tossed about by explosions.

Later on, when production on the film proper was underway, the animation team would use these motion capture sequences to quickly create animated scenes. To do this, the motion capture and animation crews would need systems capable of displaying the complex animations in real time, so that they could provide a fast response to the director and give him options during post-production.

To capture this library of motions and create the final animations, Sony Pictures Imageworks used NVIDIA Quadro® professional graphics cards. Once the motion capture sequences were recorded, the team used Windows and Linux systems equipped with Quadro and Autodesk MotionBuilder software to edit and animate the characters’ movements.

The animation team then turned these libraries of movements into the final animated sequences using workstations with Quadro cards running Autodesk Maya.

“NVIDIA’s technology enabled us to get the job done quickly using a small, tight team,” says John Meehan, motion capture supervisor from Sony Pictures Imageworks. “We’ve used Quadro for years and so we knew that when we would be facing tight deadlines on I Am Legend, we could rely on the systems to just work without worry.”

The investment in developing a library of movements up front paid off when crunch time came later on during production. The animation team could present Director Lawrence with multiple variations and versions, enabling him to compose and frame the shots for the greatest impact. The team was able to take motions from the library, blend them, and turn them into finished animations within hours, allowing the animators to focus on shot specific hero performances needed to sell the shot.

“Perhaps the payoff was biggest in the ‘infected attack the house’ scene,” says Meehan. That action scene has Smith defending his home from scores of infected mutants. “The number of animated characters in the scene was daunting, but using Quadro we were able to pull it off, using the motion capture as the basis for animating the infected and then populating the live-action shot with the animated characters. The final result is really life-like and keeps you on the edge of your seat.”