dman (03/10/83)
Red and Blue lenses at 3D movies?
What you're interested in is stereography --- the "mechanism" behind
stereo vision. While matter exists in 3-space, eyes can only recieve
a "planar" field (This field is warped due to the shape of the back
of an eye, but it is a 2 dimensonal locally flat continuous surface)
which allows the possibility of stereoscopic tricks.
Picture a 3D situation:
____---X
____----____---X
____---- ___--- X
____---- ___--- X
<@ ===___ L ___--- X
___---___ field of vision X
<@ ===____R ---___ X object
----____ ---___ X
eyes ----____ ---____ X
----____---X
---X
The left eye recieves a different field of view than the right eye,
so that this situation can be directly simulated by the placement
of filters which only allow the correct image to pass through.
r r|
b | x
r ------> r| ------> Left Eye
b | x
r r|
image image passed
red filter through filter
b = blue (left) stereo
r = red (right) pair
r | x
b b|
r ------> | ------> x Right Eye
b b|
r | x
image passed
image blue filter through filter
By filtering, the eyes can be tricked into "seeing" a stereo image.
A stereo pair (left eye, right eye) is put before the different
colored filters, each eye sees only the image it is supposed to,
and the brain assembles a stereo rendering.
red/blue planar
stereo-pair X
_ _ - -X
b_ _ - -_ _ - -X
____----b _ _- - X
____---- ___-br X
<@ r ==___ L ___--- br X
___---___ br X percieved
<@ b ==____R ---___ br X object
----____ -br_ _ X
eyes ----_r_ - -_ _ X
with filters r - - _ _ - -X
- -X
X
When the stereo pair is at the correct place in front of your eyes,
a stereo image is recieved. If am movie of a pair is projected onto
a movie screen, you get 3D movies. As a percieved object becomes
closer to your eyes, the "stereo difference" (difference between
the physical position of the same point in one image versus its
stereo pair) increases, while a far point causes the difference
goes to zero. A perception of depth can be easily "observed".
Recently COLOR 3D movies have been explored. Instead of different
color lenses, polarized lenses (90 degrees out of phase between
eyes) are used. The stereo pair is projected as two polarized
images of which only one is passed to an eye. Color 3D movies
are really quite wild.
If you have masochistic tendencies, try putting on the 3D glasses
backwards (filters reversed). Close things will become far away,
far things become right next to you, and the mental confusion should
give you big headaches.
Waiting for Holo-vision,
Dave Anderson houxa!dman