Psyc 351: Depth and Space Perception

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Psyc 351 Depth and Space Perception
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Functional Utility of Depth Perception

• Localization of objects, surfaces in 3D
• figure-ground, edge detection, grouping

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The Problem in Depth Perception

• Light doesnt tell us how far its travelled!
• Our retinas are effectively 2D - flat!
• Two solutions to this problem
• Direct
• Indirect

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Direct Solutions to Depth

• Oculomotor (Kinesthetic) and Gibsonean
• Oculomotor accommodation (no) and convergence
  (yes)
• Gibsonean texture gradients, optical flow,
  invariants

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Ocularmotor CuesAccommodation Convergence

• Accommodation the convexity of the lens
• Convergence the angle at which the two eyes
  point.

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Accommodation Convergence
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Indirect Solutions

• Use Visual Depth Cues Unconscious inference
• Binocular cues retinal disparity and stereopsis
• Monocular cues lots of them

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Binocular Cues Overview

• Disparity, crossed and uncrossed horopter
• Wheatstone stereoscope
• Panum's area
• Julesz random dot stereograms
• Correspondence problem, false matches
• Computation of disparity

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Binocular Cues, continued

• Head motion, l-r reversal, LTM, tool for
  localization
• Pulfrich effect
• Binocular rivalry, suppression
• Disparity-sensitive cortical cells
• Stereoblindness, strabismus, amblyopia
• Note lack of awareness of eye of entry

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Strabismus
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Binocular Disparity
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Binocular Disparity
A B C D
ABDC ADBC
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Disparity and the Horopter
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Disparity and the Horopter
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Stereoscopic Vision Stereoscope
Sir Charles Wheatstone, 1838
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Bela Julesz Random-dot stereograms
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Bela JuleszRandom-dotStereograms
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Magic Eye
Source magiceye.com
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False Fusions the Correspondence Problem
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False Fusions
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Binocular Rivalry
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Binocular Rivalry
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Monocular Cues to Depth

• Interposition (static or dynamic occlusion)
• Size (assumed or familiar ball and faces, Ames,
  Moon)

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Monocular Cues to Depth

• Interposition (static or dynamic occlusion)
• Size (assumed or familiar ball and faces, Ames,
  Moon)
• Size-distance coupling
• Emmert's law
• Size constancy and illusions of depth
• (Gregory's explanation of Muller Lyer)

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Monocular Cues to Depth

• Linear perspective (Alberti's window), texture
  gradients, arial perspective
• Height in the image (esp. height of bottom)
• Motion parallax relative movement
• Shading and shadows (bumps and dents)

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Pictorial (monocular) Depth Cues
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Pictorial Cues, continued
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Depth from Shading
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Depth from Texture Gradients
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Depth from Texture Gradients
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Depth the Moon Illusion
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Pictorial Depth Cues
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MorePictorialDepthCues
Shading Occlusion contours Texture gradients
dots and parallel lines
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Lichtenstein House, Washington DC
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Depth Cues in Photography DoF
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Monocular Cues to Depth

• Holway and Boring experiment cue reduction,
  breakdown in constancy
• Pitting cues against one another incongruity

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Depth, 3D Structure from Motion

• Kinetic Depth Effect
• KDE at equiluminance

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Hollow Faces (Gregory)
http//www.michaelbach.de/ot/fcs_hollow-face/index
.html Grand Illusion website The three dragons
Also Bent card illusion (Mach)
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Luminance Looming
http//www.michaelbach.de/ot/sze_lumiloom/index.ht
ml
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Trompe l'oeil art (pronounced "tromp loy)
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• Julian Beever site

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Visual Cliff (Eleanor Gibson)