2018-02-05 Depth Perception

PSY 525.001 • Vision Science • 2018 Spring

Rick Gilmore

2018-02-05 08:53:13

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But what is the Fourier Transform? A visual introduction.

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Today's topics

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Today's topics

Discuss project proposal

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Today's topics

Discuss project proposal

Depth perception

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Today's topics

Discuss project proposal

Depth perception

Discuss Leopold & Logothetis, N. K. (1996).

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Term project

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http://psu-psychology.github.io/psy-525-vision-spring-2018/project-proposal.html

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Perceiving surfaces orientation (spatiallayout)

Slant, tilt, distance

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Marr's 2.5 D sketch

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Depth perception

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"For those of a creationist bent, one could note that God must haveloved depth cues, for He made so many of them"

Yonas & Granrud, 1985, p. 45

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Kinetic

Binocular

Static (pictoral)

Sensorimotor

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Monocular (kinetic, static, some sensorimotor) vs.binocular cues

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Kinetic cues to depth

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Kinetic Depth Effect Demo

Kinetic depth e�ect (KDE)

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By Nobuyuki Kayahara - Procreo Flash Design Laboratory, CC BY-SA 3.0, Link

This one is also bistable

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Kinetic depth e�ect3D structure perceived from temporal sequence of 2D (outline-only) views.

Reported in Wallach, H., & O’Connell, D. N. (1953). The Kinetic Depth Effect.Journal of Experimental Psychology, 45(4), 205.

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Structure from Motion Demo

Structure from motion

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Archival Gibson - 1958 - Motion parallax and perceived depth

Motion parallax

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City motion parallax

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The geometry of motion parallaxWhere is fixation? What is the direction of motion?

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PJ Treffner - Occlusion demos: Accretion and deletion

Texture accretion & deletion

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Second-order motion perception

Texture accretion & deletion

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Task 1: Example of 100% Radial Optic Flow (no random dots) wit…

Optic �ow

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AR.Drone Helicopter Optical Flow Test #1

Optic �ow and autonomous �ight

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Binocular cues to depth

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StereopsisPerception of depth and 3D structure from stimulation of both eyes

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Horoptera line or surface containing all those points in space whose images fall on

corresponding points of the retinas of the two eyes.

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Random-dot stereogramsInvented by Béla Julesz

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library(imager)n_pts <- 100left_img <- array(round(runif(n=n_pts^2),0), dim = c(n_pts, n_pts))plot(as.cimg(left_img), axes=FALSE)

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right_img <- left_imgsquare_pix <- 20center_square <- right_img[floor(n_pts/2-square_pix/2):floor(n_pts/2+plot(as.cimg(center_square), axes=FALSE)

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Auto-stereogramCan't really fuse these from projected image. Why?

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The "correspondence" problemHow do retinal image points/edges correspond to object points/edges?

Why can it take time to "fuse" stereograms?

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Marr-Poggio algorithm for solvingUse: surface opacity & surface continuity heuristics

Iterate until a best-fitting solution is found

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Da Vinci stereopsisDifferent eyes see different portions of surfaces

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Geometry of self-motion, object-motion, and disparity40 / 77

Static (pictoral) cues to depth

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Linear Perspective

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Public Domain, Link

Linear perspective + elevation over horizon = Ponzoillusion

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Relative size

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Ames Room Illusion

Ames room

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Actual position ofPerson A

Apparent positionof person A

Apparentshape of room Viewing

peephole

Actual andapparent positionof person B

https://en.wikipedia.org/wiki/Ames_room

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Aerial perspective

Defocus blur

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By Joaquim Alves Gaspar - Own work, CC BY-SA 2.5, Link

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Interposition, occultation53 / 77

Texture gradients

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By Gustave Caillebotte - 5wEUCOlEf-EaVQ at Google Cultural Institute

maximum zoom level, Public Domain, Link 55 / 77

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http://psychsciencenotes.blogspot.com/2011/08/mirrors-are-literally-windows-to.html

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Lighting, shading, & shadow cues

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Sensorimotor cues to depth

Palmer's "ocular" cues

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VergenceEyes (typically) converge on a 3D point. Angle of vergence related to 3D

geometry.

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Lens Accommodation

Accommodation

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<

The accommodation re�ex

Vergence, pupil diameter change, + accommodation

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2-Minute Neuroscience: Vestibular System

Vestibular system detects head rotation, translation

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Vestibular signals speed, direction of rotation,translation

More motion parallax with head translation thanrotation

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Comparing the cues

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The human brain in depth: how we see in 3D

Integrating the cuesWelchman, A. E. (2016). The human brain in depth: how we see in 3D. Annual

Review of Vision Science. annualreviews.org. Retrieved fromhttp://www.annualreviews.org/doi/abs/10.1146/annurev-vision-111815-114605

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Heuristics

About world, illumination conditions

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Alternative view:These aren't cues; they are information. Animals don't "reconstruct" 3D space;

they perceive it directly.

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Amazing T-Rex Illusion!

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Break time

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Leopold & Logothetis, N. K. (1996)

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Core phenomenaBinocular rivalryNeural basis of binocular rivalryNeural basis of "conscious" visual experience

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Next time...

Perceptual organization

Size, shape, orientation, & position

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Slides created via the R package xaringan. Rendered HTML and supportingfiles are pushed to GitHub where GitHub's 'pages' feature is used to host and

serve the course website.

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