There are two categories of 3D technology, active and passive.
Active have electronics which interact with a display and passive two
images are projected superimposed onto the same screen.
Linearly polarized glasses
To present a stereoscopic motion picture, two images are projected superimposed onto the
same screen through orthogonal polarizing filters. The viewer wears low-cost eyeglasses
which also contain a pair of orthogonal polarizing filters. As each filter only passes
light which is similarly polarized and blocks the orthogonally polarized light, each eye
only sees one of the images, and the effect is achieved.
Linearly polarized glasses require
the viewer to keep level, as tilting of the viewing filters will cause the
images of the left and right channels to bleed over to the opposite channel.
Complementary colour anaglyphs (red and cyan)
Complementary colour anaglyphs employ one of a pair of complementary colour filters
for each eye. The most common color filters used are red and cyan.
Stereoscopy (also called stereoscopic or 3-D imaging) refers to a technique for
creating or enhancing the illusion of depth in an image by presenting two offset
images separately to the left and right eye of the viewer. Both of these 2-D offset
images are then combined in the brain to give the perception of 3-D depth. Three
strategies are used to accomplish this. The viewer wears eyeglasses to
combine separate images from two offset sources, the viewer wears eyeglasses
to filter offset images from a single source separated to each eye or the
lightsource splits the images directionally into the viewer's eyes
(no glasses required, known as Autostereoscopy).
Autostereoscopy (no glasses)
Autostereoscopy is any method of displaying stereoscopic (3D) images without
the use of special headgear or glasses on the part of the viewer. Because headgear
is not required, it is also called 'glasses-free 3D'.
Side-by-side (non-shared viewing scenarios)
photography consists of creating a 3-D illusion starting
from a pair of 2-D images, a stereogram. The easiest way to enhance depth perception
in the brain is to provide the eyes of the viewer with two different images,
representing two perspectives of the same object, with a minor deviation exactly
equal to the perspectives that both eyes naturally receive in binocular vision.
Interleaved - active shutter glasses.
Linearly polarized glasses - two images are projected superimposed onto the same screen, with the wearer wearing orthogonal polarizing filters.
Complementary colour anaglyphs - colours are filtered for each eye.
3D Stereoscopy - two offset images are sent separately to the left and right eye of the viewer, either using glasses or high frequency screens (120Hz and above) using filters.
Autostereoscopy (no glasses)
Side by Side - capable 3D
televisions take the two video feeds and make a minor deviation exactly equal to the perspectives that both eyes naturally receive in binocular vision.
Cross-eyed - White dot above image (same as side by side).
Parallel - unfocus the eyes.