Depth%20Perception,%20with%20Emphasis%20on%20Stereoscopic%20Vision

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Depth Perception, with Emphasis on Stereoscopic
Vision
Randolph Blake Visual System, Spring
Semester March 24, 2003
Chapter 10 in McIlwain and Chapter 11 in Tovee
http//www.psy.vanderbilt.edu/faculty/blake/Stereo
Stuff/Stereopsis.htm
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Specifying 3D shape and depth relations
motion
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Specifying 3D shape and depth relations
motion
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Specifying 3D shape and depth relations
motion
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Specifying 3D shape and depth relations
motion
size
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Specifying 3D shape and depth relations
motion
size
perspective
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Specifying 3D shape and depth relations
motion
size
perspective
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Specifying 3D shape and depth relations
motion
size
perspective
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Specifying 3D shape and depth relations
motion
size
perspective
texture perspective
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Specifying 3D shape and depth relations
motion
size
perspective
texture perspective
occlusion
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Specifying 3D shape and depth relations
motion
size
perspective
texture perspective
occlusion
shading
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Specifying 3D shape and depth relations
motion
size
perspective
texture perspective
occlusion
shading
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Specifying 3D shape and depth relations
motion
size
perspective
texture perspective
occlusion
shading
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Sir Charles Wheatstones Famous Invention
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Stereograms (anaglyphs)
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Stereograms (Magic Eye)
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Stereopsis (literally, seeing solid)- 3D vision
resulting from slight differences in left and
right eye images, arising because the two eyes
view the world from slightly different
perspectives
Disparity - slight differences in positions of
features in left and right eye views
crossed disparity
uncrossed disparity
zero disparity
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Magnitude of Disparity Signifies Depth Difference
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Disparity Magnitude Also Varies with Viewing
Distance
stereopsis works only within 10 - 20 ft of the
observer once the visual axes are parallel,
objects beyond the point of fixation provide no
disparity
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Magnitude of Disparity Depends on IPD
ipd interpupillary distance (averages 6.5 cm
in humans)
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Random-dot Stereograms (Julesz, 1971)
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How Theyre Made
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How Theyre Made
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How Theyre Made
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How Does the Brain Solve This Problem?
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What features does the brain match for
stereopsis?
original images
low spatial frequencies
high spatial frequencies
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What Happens When Binocular Matches Cannot Be
Found?
left eye
right eye
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Binocular Rivalry
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Neural Bases of Disparity Registration
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Neural Bases of Disparity Registration
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Neural Bases of Disparity Registration
zero disparity
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Neural Bases of Disparity Registration
uncrossed disparity
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Neural Bases of Disparity Registration
uncrossed disparity
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Neural Bases of Disparity Registration
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Neural Bases of Disparity Registration
crossed disparity
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Neural Bases of Disparity Registration
crossed disparity
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NO! Disparity must be scaled for distance.
(Recall that a given disparity can be associated
with different depth intervals, depending on
viewing distance and on IPD.)
Neurons in visual cortex can match features
between the two eyes and can compute retinal
disparity. Is the problem of stereopsis solved?

• Non-stereoscopic cues required for this depth
  scaling

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http//www.3d-web.com/index.html
http//www.stereographics.com/
http//www.psy.vanderbilt.edu/faculty/blake/Stereo
Stuff/Stereopsis.htm