These techniques simulate continuous motion by rapidly
displaying images. The viewer is given the impression that he is
watching a continuous motion. To achieve this impression the
graphical hardware needs image display rates of at least 25
images per second, since otherwise motion will look shaky. As
most graphical hardware can not reach that display rate for
moderate sized images (i.e. 256x256 pixels), one uses video
hardware. One either sends every image to a framebuffer to write
one videoframe at a time to videotape or one stores the images on
a fast accessible device, CMY a laserdisk, and, after all images
have been stored, displays them on a television screen from where
they can be put on a videotape. There are two kinds of animation
which we will describe below.
Flipbook animation
This is a well known technique. The generated images are
displayed one after the other. Its name is attached to the
thumbing or flipping through a series of images.
Keyframe animation
For this technique one only has to generate so-called keyframes.
Keyframes mark changes in the characteristics of the motion, for
example the sudden change in the direction of motion of an
electron due to a collision with an ion. Interpolation techniques
are used to generate a set of images between two keyframes. The
larger the interpolated set of images the smoother the conversion
from one keyframe to the other will appear to the viewer.
