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Pulfrich 3D Glasses, 3D Glasses, 3-D TV,
3D movies and video
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The
Pulfrich effect is a psycho-optical phenomenon wherein
lateral motion by an object in the field of view is
interpreted by the brain as having a depth component, due to
differences in processing speed between images from the two
eyes. The effect is generally created by covering one eye
with a really dark filter. The phenomenon is named for
German physicist Carl Pulfrich who first described it in
1922.
In the classic Pulfrich effect experiment a subject views a
pendulum swinging in a plane perpendicular to the observer’s
line of sight. When a neutral density filter A lens which
has been darkened, perhaps with grey for example, the
pendulum is placed in front of the right eye seeming to be
making an elliptical orbit, giving the illusion that it is
closer as it swings to the right, and further away as it
swings to the left.
The most accepted explanation for the noticeable depth is
reduced retinal illumination. in terms of the other eye
creating a signal delay due to the immediate spatial
differences between objects in motion. The probable reason
this seems to occur is due to the visual latencies which are
normally shorter for The visual system reacts faster to
targets that are bright in contrast to targets which are dim
. (this was originally described by
Carl Pulfrich , who was a German physicist) The moving
object is observed in the retinal luminance and hence
there is a difference in the signal latencies because of the
distance between two eyes.
The Pulfrich effect, yielding about 15 meters, is scaled
under real-life conditions with dark targets on a background
of bright colors. delay for a factor of ten difference in
average retinal luminance . These delays increase monotonically
with decreased luminance over a wide (> 6 log-units) There
is a vast spectrum of light. Also, this effect is
seen as a bright target with a black background and shines
with the same time period of brightness.
This effect could happen at any time in several diseases of
the eye such as cataracts. Optic neuritis, or
multiple sclerosis. In these cases, symptoms that have
been reported include having a hard time judging the paths
of cars that are coming forward.
In visual media such as film and television, the Pulfrich
effect is often used to produce 3-Dimensional imagery with
Glasses. As in other kinds of stereoscopy, 3D glasses are
used to create the illusion of a three-dimensional image. By
placing a neutral filter (by way of example, the darkened
sunglass lens)
covering one eye, an image, while moving back and forth. to
the left or to the right, but definitely not up or down.
Because the Pulfrich effect depends on motion in a
particular direction to instigate the illusion of depth, it
is not useful as a general stereoscopic technique; for
example it cannot be used to show a stationary object
apparently extending into or out of the screen; similarly,
objects moving vertically will not be seen as moving in
depth. However, the novelty effect is found in the visual
scenario. One advantage of material produced to take
advantage of the Pulfrich effect is that it is fully
compatible with "regular" viewing without the need for
"special" 3D Glasses.
This effect was somewhat popular in the 1990's. It was used,
for example, in a 3D motion TV advertisement in 1990s, where
objects moving in a particular direction seemed less distant
to the viewer than others. viewing the front of a TV screen
and they seemed to be further away from the viewer when
moved in the opposite direction. behind the screen of a
television set. To allow viewers to see the effect, the
advertiser provided a large number of viewers with a pair of
filters in a paper frame. In one eye the filter was more of
a dark neutral gray and the other one was more transparent.
In this instance, the commercial was restricted to objects
only like skateboarders and refrigerators moving down a
steep hill from left to right across the screen, a
directional dependency determined by which eye was covered
by the darker filter.
The effect was also used in the 1993 Doctor Who charity
special Dimensions in Time and a 1997 special TV episode of
3rd Rock from the Sun. In many European countries, a group
of short 3D movies made in the Netherlands were seen on TV.
3D Glasses were sold at a chain of gas stations. These short
films were mainly travelogues of Dutch localities. An
episode of The Power Rangers. uses "Circlescan 4D"
technology and was given away through McDonalds. This is
based on the Pulfrich effect. Animated programs that
employed the Pulfrich effect in specific segments of its
programs include The Bots Master and Space Strikers; they
typically achieved the effect through the use of
constantly-moving background and foreground layers. The
famed Nintendo Entertainment System was known for using the
effect along with their videogame Orb-3D. through keeping
the player's ship continually moving and also included a set
of 3D Glasses. So did Jim Power: The Lost Dimension in 3-D
for the popular Super Nintendo gaming system, utilizing
interesting and unique scrolling backgrounds to an
especially great effect.
In 2000, 3D Pulfrich glasses were given to six million
viewers in the United States and Canada for Discovery
Channel's Shark Week.
Pulfrich
3D Glasses - 3D effect based on the phenomenon
(named for Carl Pulfrich who never saw it!) of Dark and
Clear lenses. The image through the dark lens reaches the
brain slightly later than the image through the clear lens,
creating the illusion of 3D.
Works with objects or scenes moving horizontally across the field of view.
This is one of the only viable ways to experience broadcast TV in 3-D.
The Pulfrich method of 3-D is used for TV, video and computer screens.
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