Computer-assisted animation is used on an animated feature for a number of reasons. Additionally, computer-assisted animation can be used for both traditional 2D and 3D animation to enhance the overall quality or expedite the making of an animated film.

Function

Animators use a computer to do things they couldn't accomplish without difficulty without a computer, like in-betweening, according to NationMaster.com.

Traditional

In traditional cel animation, hand-drawn images are strung together, giving the impression of movement. However, there are visual "gaps" between frames, which, according to NationMaster.com, are "closed" by transition drawings between the images.

Time Saving

Drawing the pictures that go between two cels is time-consuming. According to NationMaster.com, a computer can be used to cut down on the time it takes to create the transition drawings or in-betweens.

Motion Capture

Animation is more than cartoons. For example, the technique known as motion capture is a computer-assisted animation technique, according to "The New York Times." It was used in "The Lord of the Rings" to create Gollum.

Motion Capture in Action

Gollum was created by placing reflective dots on the actor's body. The information from the dots was fed into a computer, which later provided a physical structure like bones onto which the animators could affix the outward appearance of Gollum.

Source:

"NY Times": Summer Films: The Future: Me Tarzan, Me Computer Assisted

NationMaster.Com: Encyclopedia: Tweening

Sci Fi: How an Animated Cartoon Is Made

More Information:

Bringing Gollum to Life

Motion Tweening and Frame Animation