Computer animation

Computer animation is the process used for digitally generating moving images. The more general term computer-generated imagery (CGI) encompasses both still images and moving images, while computer animation only refers to moving images. Modern computer animation usually uses 3D computer graphics. Computer animation is a digital successor to stop motion and traditional animation. Instead of a physical model or illustration, a digital equivalent is manipulated frame-by-frame. 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 per second). This technique is identical to how the illusion of movement is achieved with television and motion pictures. To trick the visual system into seeing a smoothly moving object, the pictures should be drawn at around 12 frames per second (which, when animating on 24 frames per second, is called "animating on twos”) or faster (a frame is one complete image). At rates below 12 frames per second, most people can detect jerkiness associated with the drawing of new images that detracts from the illusion of realistic movement. Conventional hand-drawn cartoon animation often uses 15 frames per second in order to save on the number of drawings needed, but this is usually accepted because of the stylized nature of cartoons. To produce more realistic imagery, computer animation demands higher frame rates. Films seen in theaters in the United States run at 24 frames per second, which is sufficient to create the appearance of continuous movement.