POST PRODUCTION MOTION CAPTURE
CAPTURING MOTION SFX specialist Amitaabh Naaraayan sheds light on the art of motion capture and how it is increasingly being used in Hollywood. Motion capture, as the name suggests is a process of capturing Motion from live actors. Motion capture requires more than just actors; it requires talented performing artists who are a good mix of actors, stuntmen and dancers. These artists have to wear a body suit with light points attached on the suit; these light points are usually placed to coincide with joints or on muscles with prominent movements like the facial muscles. The artists then rehearse to move their bodies to fit the virtual 3D characters as per the scripts. The motion capture cameras capture the light positions as the actors move and enact their scenes. The captured information is stored as lines (animation curves) and numeric data commonly referred to as keyframes. With the help of sophisticated software this data is then transferred to the 3D characters. The scenes could be a green screen setup, built to match the conditions
32 MAY 2010
of the 3D scenes in any sequence of the film. The moving characters are then simply placed in these 3D scenes. With a combination of the new virtual camera software, filmmakers have realised unlimited freedom in computer-generated storytelling. The director can now move within a computer-generated 3D environment, in and around CG actors whose infinitely looping performances have been created using standard motion-capture technology, to get the results conceived by the writers and directors. James Cameron has set a new standard for filmmakers with his recent hit Avatar. Cameron continuously maintained that Avatar was not a CG animated film; rather that it was “motion tracked and CG rendered”. An increasing number of filmmakers have begun to use Mocap to capture the entire performance, ie. the acting, body language and the voice, vis-à-vis just the voice of the famous celebrities.
Motion capture based animation is essential for creating characters that move realistically, in situations that would be impractical or too dangerous for real actors. Director, Steven Spielberg is said to be using motion-capture technology, as it is allowing him to digitally recreate the look of the original Tintin comics by Hergé on the silver screen. Hergé wrote about fictional people in a real world, not in a fantasy universe. It was the real universe he was working with, and he used National Geographic to research his adventure stories. Not only are the actors represented in real time, they enter into a three-dimensional world. Software tools for working with motioncaptured data, such as Autodesk MotionBuilder have evolved to the point where animators now have the means to edit and blend takes from multiple capture sessions and mix and match them with keyframed animation techniques; allowing great control of style and quality of final output, for anything
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