An interesting tidbit on the new 3D movie technology:

Unlike the 3-D movies of past decades, where two separate projectors displayed images (one for each eye) and had to remain synchronized for the duration of the film, the latest 3-D systems use a single digital projector. They quickly alternate between images seen by the right and left eyes, which the brain marries into a three-dimensional picture. The process still requires glasses to pick up separate left and right eye images, but not the clunky red and green kinds popularized in the 1970s and 1980s with 3-D films. Today's 3-D eyewear looks more like sunglasses.

== using separation in time after separation in space.