Course Presentation
Multimedia Systems
3D Technologies
Mahdi Amiri
May 2011
Sharif University of Technology
Binocular Vision (Two Eyes)
Advantages
A spare eye in case one is damaged.
A wider field of view (FOV).
Maximum horizontal FOV of humans: ~200º (with
two eyes)
One binocular FOV (seen by both eyes): ~120º
Two uniocular FOV (seen by only one eye): ~40º
Binocular summation: The ability to detect faint
objects is enhanced (neural summation).
Perception of depth.
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Multimedia Systems, Spring 2011, Mahdi Amiri, 3D Technologies
Depth Perception
Cyclopean Image
Cyclopean image is a single mental image of a scene
created by the brain by combining two images received
from the two eyes.
The mythical Cyclops
with a single eye
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Depth Perception
Cues (Cont.)
Accommodation of the eyeball (eyeball focus)
Focus by changing the curvature of the lens.
Interposition
Occlusion of one object by another
Occlusion
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Depth Perception
Cues (Cont.)
Linear perspective (convergence of parallel edges)
Parallel lines such as railway lines
converge with increasing distance.
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Depth Perception
Cues (Cont.)
Familiar size and Relative size
subtended visual angle of an object of known size
A retinal image of a small car is also
interpreted as a distant car.
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Depth Perception
Cues (Cont.)
Aerial Perspective
Vertical position (objects higher in the scene
generally tend to be perceived as further away)
Haze, desaturation, and a shift to bluishness
Hight
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Shift to bluishness
Multimedia Systems, Spring 2011, Mahdi Amiri, 3D Technologies
Haze
Depth Perception
Cues (Cont.)
Light and Shade
Shadow
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Depth Perception
Cues (Cont.)
Change in size of textured pattern detail.
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Depth Perception
Cues (Cont.)
Motion parallax
When an observer moves, the apparent relative motion of
several stationary objects against a background gives hints about
their relative distance.
This effect can be seen clearly when driving in a
car. Nearby things pass quickly, while far off
objects appear stationary.
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Depth Perception
Cues: Stereopsis
We see a single, Cyclopean,
image from the two eyes' images.
The cube is shifted to the right in left
eye's image.
A person’s eye are about 65mm apart
from each other. The two eyes converge
on the object of attention.
The cube is shifted to the left in the
right eye's image.
The brain gives each point in the Cyclopean
image a depth value, represented here by a
grayscale depth map.
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Multimedia Systems, Spring 2011, Mahdi Amiri, 3D Technologies
Depth Perception
Cues, Summary
Monocular Cues (involve those cues that exist for a
single eye)
Accommodation of the eyeball
Interposition (Occlusion)
Linear perspective
Familiar size and Relative size
Aerial Perspective
Light and Shade
Change in size of textured pattern
Monocular Movement Parallax
Binocular Cues (Cues that involve both eyes)
Stereopsis
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3D Technologies
Types of 3D Displays
Stereoscopic
Provides a different image to the viewer's left and
right eyes (generally user has to use special spectacles).
Autostereoscopic
Uses optical components in the display, rather than worn
by the user, to enable each eye to see a different image.
Computer-Generated Holography (CGH)
Create a light field identical to that which would
emanate from the original scene.
Volumetric displays
Display points of light within a volume. Such displays
use voxels instead of pixels.
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Stereoscopy
Definition
Presenting two offset images separately to the left and
right eye of the viewer.
Three strategies:
Have the viewer wear eyeglasses to combine
separate images from two offset sources.
Have the viewer wear eyeglasses to filter offset
images from a single source separated to each eye.
Have the light source split the images directionally
into the viewer's eyes (no glasses required
, Autostereoscopy).
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Charles Wheatstone
1802-1875
Stereoscopy
Two Offset Sources
Stereoscope
A stereoscope is composed of two pictures mounted next to each other, and a set of lenses to view the pictures
through. Each picture is taken from a slightly different viewpoint that corresponds closely to the spacing of
the eyes. The left picture represents what the left eye would see, and likewise for the right picture. When
observing the pictures through a special viewer, the pair of two-dimensional pictures merge together into a
single three-dimensional photograph. First invented by Sir Charles Wheatstone in 1838.
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Stereoscopy
Two Offset Sources
Viewers
Conway Stereo Viewer
Head-Mounted Display (HMD)
An HMD with a separate video source displayed in front
of each eye to achieve a stereoscopic effect.
1920s-30s Stereo Viewer
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Stereoscopy
Filtering Single Source
Autostereogram
Anaglyph image
Polarization of light
Linearly polarized
Circularly polarized
Anaglyph (3D photograph) of a
column head in Persepolis, Iran.
A linear polarizer converts an unpolarized beam into
one with a single linear polarization. The vertical
components of all waves are transmitted, while the
horizontal components are absorbed and reflected.
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Autostereogram
Stereogram
3D craze of the 90’s
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www.magiceye.com
Autostereogram
Stereogram
3D craze of the 90’s
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Autostereogram
Stereogram
3D craze of the 90’s
www.magiceye.com
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Autostereogram
Viewing Instructions
The hidden image
Magic Eye images may be easier to see if viewed on paper rather than a
computer screen. If possible, print this image and follow the instructions
below. (You don't need to print in color.)
Hold the center of the printed image right up to your nose. It should be
blurry. Focus as though you are looking through the image into the distance.
Very slowly move the image away from your face until the two squares above
the image turn into three squares. If you see four squares, move the image
farther away from your face until you see three squares. If you see one or two
squares, start over!
When you clearly see three squares, hold the page still, and the hidden
image will magically appear. Once you perceive the hidden image and depth,
you can look around the entire 3D image. The longer you look, the clearer the
illusion becomes. The farther away you hold the page, the deeper it becomes.
Good Luck!
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Autostereogram
Random Dot Autostereogram
The hidden image
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Autostereogram
Random Dot Autostereogram
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Dr. Bela Julesz
Autostereogram
Stereogram
Random dot stereogram was invented by Dr. Bela Julesz in 1959.
Fig. 1. By using uniform,
randomly distributed dots,
Dr. Julesz eliminated the
depth cues that are inherent
in recognizable images.
Fig. 2. Within the rectangle
select a group of dots that make
up a small shape (here a circle).
Fig. 3. Create a new rectangle
identical to the original rectangle,
except that the dots within the small
shape have been shifted to the left.
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Fig. 4. When the two
rectangles (Fig. 1 and Fig. 3)
are viewed together as a
stereo pair, the image of the
circle appears to float above
the background.
Multimedia Systems, Spring 2011, Mahdi Amiri, 3D Technologies
Christopher Tyler
Autostereogram
Birth of Autostereogram
In 1979, Christopher Tyler, a student of Dr. Julesz, assisted by computer programmer
Maureen Clarke, discovered that the offset scheme could be applied to a single image.
The hidden image
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Anaglyph Image
Concept
Red-blue glasses
Red-cyan glasses
cyan = green + blue
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The anaglyph method produces two slightly offset images, each
individually tinted in either red or cyan. The red-cyan glasses then
filter the light appropriately, meaning individual eyes only see the
image meant for them. The brain then merges the two slightly
different images to produce the 3D effect. This is the main process
currently being used on 3D Blu-Ray releases and on TV broadcasts.
Multimedia Systems, Spring 2011, Mahdi Amiri, 3D Technologies
www.decotechsoftware.com/sim/manual/pages/others/basic_concepts_of_stereo_img.html
Anaglyph Image
Concept
How to create
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Anaglyph Image
Example
3D Box
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Anaglyph Image
Computer Process
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3D Technologies
That’s not all.
To be continued…
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Polarization of Light
Concept
Linear Polarized 3D Glasses
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The polarised method is one which is becomming the
method of choice when displaying 3D images. Two
images are projected at right angles to each other which
are then filtered by the polarising glasses, again meaning
each individual eye only sees the image intended for it,
much in the same was as the anaglyph method.
Multimedia Systems, Spring 2011, Mahdi Amiri, 3D Technologies
Polarization of Light
The Common Types of Polarizers
Linear
Eyeglass contain a pair of
orthogonal polarizing filters
Low-cost eyeglasses
If viewers tilt their heads  Corrupts
Circular
The most widely used technology
for watching 3-D films in theatres
Right-handed/Clockwise circularly polarized light displayed
with and without the use of components. This would be
considered Left-handed/Counter-Clockwise circularly
polarized if defined from the point of view of the source.
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Polarization of Light
Circular Polarization
RealD glasses
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A Left-handed/counter-clockwise
circularly polarized wave as defined
from the point of view of the source.
A right-handed/clockwise circularly
polarized wave as defined from the
point of view of the source.
Multimedia Systems, Spring 2011, Mahdi Amiri, 3D Technologies
3D Technologies
Autostereoscopic
Concept
Example of parallax barrier. Each eye sees
different pixels of the image.
Comparison of parallax-barrier and lenticular
autostereoscopic displays. Note: The figure is
not to scale.
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3D Technologies
Autostereoscopic
Example devices
The Nintendo 3DS uses parallax
barrier autostereoscopy to
display a 3D image.
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3D Technologies
Holography
Invented in 1947 by Dennis Gabor.
Holography is a technique that allows the light
scattered from an object to be recorded and later
reconstructed so that when an imaging system (a
camera or an eye) is placed in the reconstructed
beam, an image of the object will be seen even
when the object is no longer present.
Dennis Gabor, 1900-1979
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Holography
Concept
Holographic recording process
Holographic reconstruction
process
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Holography
ABC
ABC
Workspace
Holographic recording process
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Holography
Interference
ABC
Interference
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Holography
Diffraction
Diffraction example
Diffraction
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Volumetric Display
Voxels
A series of voxels in a stack with a
single voxel highlighted.
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3D Technologies
A pair of CrystalEyes
shutter glasses
Liquid Crystal (LC) Shutter Glasses
Pros
Mostly eliminate "ghosting" which is a problem with other 3D
display technologies such as RealD 3D
Unlike red/cyan color filter 3D glasses, LC shutter glasses are
color neutral enabling 3D viewing in the full color spectrum.
Cons
Flicker can be noticeable except at very high refresh rates, as each eye
is effectively receiving only half of the monitor's actual refresh rate.
LC shutter glasses are shutting out light half of the time ... darker
picture perceived by the viewer.
Expensive glasses (Over $100)
Shutter glasses are also matched to the TV so it may not be possible to
use your shutter glasses with a different brand 3DTV.
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3D Technologies
ABC
Ghosting
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Multimedia Systems
3D Technologies
Thank You
FIND OUT MORE AT...
1. http://ce.sharif.edu/~m_amiri/
2. http://www.dml.ir/
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