Lecture 16 Flashcards

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1
Q

What is a cue approach to depth perception?

A

A cue approach to depth
perception focuses on information
in the retinal image that is correlated
with depth in the scene

  • We learn the connection between
    cue and depth (e.g. occlusion)
  • Association becomes automatic
    through repeated exposure
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2
Q

What are oculomotor cues?

A

based on sensing
the position of the eyes and muscle
tension

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3
Q

Describe convergence

A

inward movement of
the eyes when we focus on nearby
objects

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4
Q

Describe accommodation

A

the shape of the
lens changes when we focus on
objects at different distances

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5
Q

Describe monocular cues

A

information that
can be based on the image from a
single eye

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6
Q

Describe pictorial cues

A

sources of depth information that come from 2-D images, such as
pictures

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7
Q

Describe occlusion

A

when one object partially covers another

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8
Q

Describe relative horizon

A
  • Objects below the horizon (an imaginary horizontal line that is at the same level as the observer,
    or ‘eye-level’) that are higher in the field of vision are more distant (motorcycle 2 vs. motorcycle 1)
  • Objects above the horizon that are lower in the visual field are more distant (cloud 4 vs. cloud 5)
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9
Q

What is relative size?

A

when objects are
equal size, the closer one will take
up more of your visual field

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10
Q

Describe perspective convergence

A

parallel lines appear to come together in the
distance

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11
Q

Describe atmospheric perspective

A

distance objects appear more ‘fuzzy’
* Occurs because the farther away something is, the
more air/particles we have to look through to see it

  • Farther objects also tend to appear more ‘blue’ (for
    the same reason the sky looks blue, i.e. our
    atmosphere preferentially scatters short wavelengths
    and looking ‘through’ more of increases the
    ‘blueness’ this imparts on our perpeption
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12
Q

Describe texture gradient

A

equally spaced elements are more
closely packed as distance increases

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13
Q

Describe shadows

A

helps enhance depth by indicating
where objects/features are located

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14
Q

Describe motion parallax

A

close objects in
direction of movement glide rapidly
past but objects in the distance
appear to move slowly

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15
Q

Describe deletion and accretion

A
  • Deletion and accretion: objects are covered or uncovered as we move relative to them
  • Deletion refers to covering an object
  • Accretion refers to uncovering an object
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16
Q

What is stereoscopic depth perception?

A

constructed based on input provided to
both eyes

the basis for how 3D glasses typically
work
* This has been accomplished by presenting different images to each eye using
various techniques (e.g. shutters, red/blue filters, polarized lenses, etc.)

17
Q

Describe corresponding retinal points

A

points on the retina that would overlap if the eyes were
superimposed on each other

18
Q

Describe binocular disparity

A

the difference in images from two eyes

19
Q

What is the horopter?

A

an imaginary sphere that passes through the point of focus
* Objects on the horopter fall on corresponding points on
the retinas
* e.g. both Julie and the tree fall on the horopter, therefore
we know that they each fall on corresponding points
on the retinas
* This also tells us that they are both approximately the
same distance away from the observer

20
Q

Describe non-corresponding points

A

Objects that are not on the horopter fall on non-corresponding points

  • These points make disparate images
  • The degree to which these images deviate from corresponding points is the
    absolute disparity (and can be represented by a calculation referred to as the
    angle of disparity)
21
Q

Describe crossed disparity

A

whenever an object is closer to the observer
than where they are looking (in front of the horopter)

22
Q

Describe uncrossed disparity

A

whenever an object is farther away from the
observer than where they are looking (behind the horopter)

23
Q

Describe binocular disparity

A
  1. Determining whether disparity is crossed or
    uncrossed tells us whether something is behind
    or in front of our point of focus (i.e. the horopter)
  2. Because objects that are farther away from the
    horopter create larger angles of disparity, this
    information tells us how far away something is
    from the horopter
  • All taken together then, the nature of the disparity
    (crossed or uncrossed), along with the angle of
    disparity, helps us judge where things are in space
24
Q

What is stereopsis?

A

depth information
provided by binocular disparity

25
Q

What are stereoscopes?

A

viewers which use two
pictures from slightly different viewpoints

26
Q

Describe random-dot stereograms

A

Random-dot stereograms have two
identical patterns of ‘noise’ with one ‘piece
of information’ shifted in position