Computer animation

Computer animation is the process used for digitally generating animations. The more general term computer-generated imagery (CGI) encompasses both static scenes (still images) and dynamic images (moving images), while computer animation only refers to moving images. Modern computer animation usually uses 3D computer graphics. The animation's target is sometimes the computer itself, while other times it is film.

Computer animation is essentially a digital successor to stop motion techniques, but using models and traditional animation techniques using frame-by-frame animation illustrations. Also computer-generated animations allow a single graphic artist to produce such content without using actors, expensive set pieces, or props. To create the illusion of movement, an image is displayed on the computer monitor and repeatedly replaced by a new similar image but advanced slightly in time (usually at a rate of 24, 25, or 30 frames/second). This technique is identical to how the illusion of movement is achieved with television and motion pictures.

For 3D animations, objects (models) are built on the computer monitor (modeled) and 3D figures are rigged with a virtual skeleton. Then the limbs, eyes, mouth, clothes, etc. of the figure are moved by the animator on key frames. The differences in appearance between key frames are automatically calculated by the computer in a process known as tweening or morphing. Finally, the animation is rendered.

For 3D animations, all frames must be rendered after the modeling is complete. For pre-recorded presentations, the rendered frames are transferred to a different format or medium, like digital video. The frames may also be rendered in real-time as they are presented to the end-user audience. Low bandwidth animations transmitted via the internet (e.g. Adobe Flash, X3D) often use the software on the end user's computer to render in real-time as an alternative to streaming or pre-loaded high bandwidth animations.