King Kong as we see him in the movie is an animated 3-D computer model. (To learn about creating 3-D models, see How 3-D Graphics Work.) King Kong's fur was the hardest to animate -- it's very difficult to make hair or fur look and move in a realistic way. Weta Digital faced similar challenges with Gollum, when they had to move each strand of hair on his head individually to coincide with the movement of Gollum's body. With Kong, the model is covered in fur almost head to toe. Getting the fur to move with the skin was an animating feat.
Animation is more flexible than motion capture. Animators alter and supplement the motion-capture performance when applying it to the 3-D model. They basically use Serkis' performance as a guide, laying it onto King Kong in the process of keyframe animation.
Keyframe animation entails programming key poses for a digital model that will create a framework for the model's movement. An animator typically works on a single scene until it's done, setting the exact position of King Kong's arm in one particular frame, and then the position of his arm a second later, so they look exactly right. The 3-D graphics software helps to fill in the motion that happens in between, creating transitions between each frame. In addition to body movement, animators also keyframe the face, pinpointing spots that they'll manipulate to achieve certain facial expressions. They heavily manipulate the eyes and the brow to make King Kong happy, angry, sad or confused. Using both motion-capture footage and their own research on gorilla mannerisms, they identify each point necessary to achieve a certain look and keyframe the stages in that facial expression or body movement.
Animating King Kong was not a sedentary task. The animators acted out each scene segment to get a sense of what it should feel like. They swung from doorframes in the Weta Digital offices. They role-played gorillas and dinosaurs and fought each other on the floor by their desks. For each second of each scene where King Kong is present, animators spent hours making it look real. They applied the motion-capture performance to the 3-D model, interpreted it within the context of the scene, acted it out, keyframed it, altered it and hand-animated every eye movement, nostril flare and lip twitch. In the end, the animators have translated Serkis' motion into King Kong's motion to create the actual digital performance you see in the movie.
For more information on King Kong, motion capture and digital animation, check out the links on the next page.