Physics
and other Applications
(image
courtesy of 3dglasses online)
Stereoscopy is the technique of recording
three-dimensional
visual information in two-dimensional media by creating the illusion of
depth
in an image. In order to achieve this illusion of depth in a
photograph, movie,
or other two-dimensional image a slightly different image is presented
to each
eye. Stereoscopic imaging (also called “real 3D”) requires a minimum of
two
pictures which simulate both eyes at the same time. Traditional
stereoscopic
photography consists of creating a 3D illusion starting from this pair
of 2D
images. The easiest way to create depth perception is to provide the
viewer’s
eyes with two different images, representing two perspectives of the
same
object to the brain, with minor deviations similar to the perspective
that both
eyes naturally receive in binocular vision. This can either be
accomplished by
using traditional photography (stereo photography), computers (virtual
reality), or lasers (holography). 3D images can either be displayed as
pairs in
a 3D viewer (for slides), or on a computer. Other formats include
anaglyph
pictures which use red-blue 3D glasses (shown below) and digital stereo
projection which uses
either “passive” polarized 3D glasses (shown above) or with “active”
LCD shutter glasses.
Stereoscopy is used in photogrammetry,
organic
chemistry, x-rays and also for entertainment through the production of stereograms. Stereoscopy is useful in viewing
images
rendered from large multi-dimensional images produced by experimental
data.
Modern industrial 3D photography may use lasers or other advanced
techniques to
detect and record 3D information.
(image
courtesy of Howstuffworks.com)
Eye
Anatomy
The eye is a
complex sensory organ specialized for gathering
visual information from the surroundings. Each eye includes a lens
system to
focus the image, a layer of photosensitive cells called rods and cones,
and a network
of cells and nerves that collect, process and transmit visual
information to
the brain, all surrounded by a fibrous protective globe. The eyes are
housed in
protective bony structures of the skull called the orbits. Each eye is
composed
of a tough outer layer, the sclera and cornea; a middle layer, the
choroid,
ciliary body and iris; and an inner layer of nerve tissue called the
retina.
The photosensitive retina connects to the brain via the optic nerve.
(image courtesty of Biology
6th edition )
Photogrammetry
Stereoscopy is applied to photogrammetry, which is used in making scaled and topographic maps. First, aerial photographs are taken from an aircraft with a specially mounted and precise camera. Photographs are then taken at intervals along a run so that they overlap. Then, the precise locations of the same control points are measured on the ground so that the photographs can be scaled relative to the true ground dimensions. The photographs are exposed on special high resolution film and film processing is precisely controlled to minimize distortion of the terrain.
When the control
has been computed and enough points of
known coordinates are available, two overlapping photographs are placed
in a
photogrammetric plotter. Using a series of complex optics, a
photogrammetrist
looks at the overlapping are where portions are superimposed and sees
that area
in 3D. By placing an optical marker called a floating point on the
surface, he
locates the 3D coordinates of that point. He can then move the floating
mark
along a geographical feature, and at the same time, a pantograph will
move a
pencil to record that feature on a piece of paper, thus creating a map.
Chemistry
Stereoscopic images
help chemists visualize complex molecule
shapes and deal with the specific topic of chirality. Though two
molecules may
be composed of the same atoms, they can have different chemical
activity
depending on their “handedness,” similar to the left and right hands of
humans.
Some of these non-superimposable images are optically active which
makes them a
very important topic for pharmacists and organic chemists. Stereoscopic
images
are perfect for illustrating these differences.
(image courtesty of Organic Chemistry Fourth Edition))