Key Frame and Motion Capture

Photo courtesy New Line Actor Andy Serkis in a motion capture suit

There are two general ways to create realistic motion: key-frame animation and motion capture. To bring Gollum to life, the animators had to rely on both.

With key-frame animation, animators move all of the sliders "by hand" and control every part of the character's motion frame by frame. Since the body of a CG character can have up to 100 sliders to control all of the different parts of the body, and since the face can have another 100 sliders (or more), this can be a meticulous and time-consuming process.

With motion capture, the filmmakers take an actor or actress and dress him or her in a special suit. The suit has dozens of reflective markers on it. A set of video cameras records the actor/actress playing out a scene from several different angles. Then a computer looks at the motion of all of the markers and uses their movements to program the sliders for the animated character.

For some of Gollum's scenes, an actor named Andy Serkis (who provided Gollum's voice throughout the trilogy) put on a motion-capture suit and played the part. Andy's motion drove the movement of Gollum's body in the movie. In other scenes, the animators used key-frame animation to control Gollum's body. In all of the scenes, they used key-frame animation to move Gollum's face.