Task 6: 3D Flashcards Preview

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Flashcards in Task 6: 3D Deck (49)
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1
Q

Perception of objects and scene is based on what kind of retinal image?

A

2D retinal image

2
Q

What do cues explain?

A

How retinal 2D image gives depth

3
Q

Oculomotor cues

- where do they work?

A

Cues based on our ability to sense the position of our eyes and tension in our eye muscles
- close range (up to 2 meters)

4
Q

Name 2 oculomotor cues

A
  1. convergence

2. accomodation

5
Q

Convergence

A

Inward movement of eyes that occurs when we look at nearby objects.

6
Q

Accommodation

A

Change in shape of lens (lens flattens) that occurs when we focus on objects at various distances

7
Q

Monocular cues

A

Cues that work with one eye. These include accommodation, pictorial cues and motion-produced cues.

8
Q

Occlusion (monocular pictorial cue)

A

Occurs when one object (partially) hides another from view

9
Q

Relative size (monocular pictorial cue)

A

When two objects are of equal size, the one farther away will take up less of our field of view than the one closer.

10
Q

Familiar size (monocular pictorial cue)

A

Cue used when judging distance based on prior knowledge of size of objects.

11
Q

Texture gradient (monocular pictorial cue)

A

Elements equally spaced in scene appear to be more closely packed as distance increases.

12
Q

Shadows (monocular pictorial cue)

A

Decreases in light intensity caused by blockage of light that provide info about location of objects.

13
Q

Atmospheric pressure (monocular pictorial cue)

A

Occurs when distant objects appear less sharp than nearer objects, with a slight blue tint. Works above 30m

14
Q

Perspective convergence (monocular pictorial cue)

A

Cue experienced when looking down parallel lines that appear to converge in distance.

15
Q

Relative height (monocular pictorial cue)

A

Objects with their bases closer to horizon are usually seen as being more distant. Works from 2m.

16
Q

Motion-produced cues

A

Cues that emerge when we start moving, that enhance our perception of depth. Both work at close and medium ranges (up to 20 meters)

17
Q

Motion parallax (monocular motion-produced cue)

A

Occurs when nearby objects appear to glide rapidly past us, but more distant objects appear to move more slowly.

18
Q

Deletion and accretion (monocular motion-produced cue)

A

As an observer moves sideways, some things become covered (= deletion), and others become uncovered (= accretion).

19
Q

Binocular cues

A

rely on info from both eyes

20
Q

Stereoscopic vision

A

ability to use binocular disparity as a cue to depth

21
Q

Strabismus

A

misalignment of the eyes (cross eye), visual system suppresses vision in one of the eyes to avoid double vision so the person sees the world with one eye at a time

22
Q

Binocular disparity

A

Differences between two retinal images of same scene. Basis for stereoscopic vision

23
Q

Corresponding retinal points

A

points on retina that overlap if eyes are superimposed on each other

24
Q

Horopter

A

Imaginary circle that passes through point of focus. Surface of zero disparity.

25
Q

Non-corresponding points

A

Images of objects that are not on horopter fall on noncorresponding points.

26
Q

Absolute disparity

A

Degree to which these objects deviate from falling on corresponding points. It is determined by measuring angle between where corresponding point would be located and where it is actually located.

27
Q

Angle of disparity

A

angle between corresponding (0) and non-corresponding (not 0) retinal points

28
Q

Crossed disparity

A

Sign of disparity produced by objects in front of horoptor. Objects located in front of horopter appear to be displaced to the left in right eye, and to the right in left eye.

29
Q

Uncrossed disparity

A

Sign of disparity produced by objects behind horoptor. Objects located behind horopter appear to be displaced to the right in right eye and to the left in left eye.

30
Q

Relative disparity

A

Difference in absolute disparities of objects in a scene that remains the same as an observer looks around a scene.

31
Q

Stereopsis is related to ________, the experience of depth created by disparity

A

perception

32
Q

Stereopsis

A

impression of depth that results from information provided by binocular disparity

33
Q

Stereoscope

A

Device for simultaneously presenting slightly different images to one eye and the other, producing an illusion of depth because it creates same binocular disparity that occurs when a person views the scene naturally.

34
Q

Random-dot stereogram

A

Stereogram made of large number of randomly placed dots, that contains no monocular cues to depth. Aimed at showing that disparity alone can result in depth perception.

35
Q

Correspondence problem

A

Visual system must compare images of left and right retinas in order to calculate the amount of disparity.

36
Q

Binocular depth cells (disparity-selective cells)

A

– Respond best when stimuli presented to left and right eyes create specific degree of absolute disparity.

37
Q

Neurons in the ___ are sensitive to absolute disparity

A

primary receiving area

38
Q

Neurons in the ___ and other areas are sensitive to relative disparity

A

temporal lobe

39
Q

Our perception of ___ can be affected by our perception of ____

A

size, depth

40
Q

Visual angle

A

Angle of object relative to observer’s eye that is determined by extending lines from person to the lens of observer’s eye.

41
Q

Size constancy

A

Fact that our perception of object’s size is relatively constant, even when we view object from different distances.

42
Q

Size-distance scaling

A

Idea that perceiver combines the size of object formed on retina and its distance to perceive the actual size of an object

43
Q

Equation for size distance scaling

A

s = k ( r x d )

s= perceived size
k= constant 
r= retinal image size
d= perceived distance
44
Q

Emmert’s law

A

The farther away an afterimage appears, the larger it will seem.

45
Q

Misapplied size constancy scaling (gregory 66)

A

Explanation for this effect proposing that mechanisms that help us perceiving in 3-D world sometimes create illusions when applied to objects drawn on 2-D surface.

46
Q

Conflicting cues theory (day 90)

A

– Our perception of line length depends on (1) actual length of vertical lines and (2) overall length of figure.

47
Q

Where are the cells for

a) signalling disparity; binocular disparity starts here
b) extracting illusory contours

A

a) v1

b) v2

48
Q

What neurons are responsible for stereopsis?

A

V1 V2 V5

49
Q

Neurons responsible for pictorial cues

A

V2