Lecture 15 Size and Depth

Question 1

Describe how the trichromat’s brain converts relative differences to colour.

Answer 1

• detect significant differences in the pattern of firing across the 3 cone types
• i.e. distinguish green and yellow as more distinct representations, which their perceptual system would then create more distinct experiences of colour for

Question 2

Describe how the protanope’s (missing long cone) brain converts relative differences to colour. How does it compare to the trichromat?

Answer 2

• like the trichromat, this type of dichromat has similar responses to both 500 and 570 nm light
• only difference is a SLIGHT CHANGE in how their short cones respond (to green vs yellow)
• therefore, less differentiated response to 500 and 570 nm light
• perceive only SLIGHTLY DIFFERENT colour experiences

Question 3

What is the cue approach to depth perception?

Answer 3

focuses on information in the retinal image that is correlated with depth in the scene

Question 4

How does the association between cue and depth become automatic for us?

Answer 4

by repeated exposure

Question 5

What are oculomotor cues?

Answer 5

cues based on sensing the position of the eyes and muscle tension

Question 6

What is convergence in terms of oculomotor cues?

Answer 6

inward movement of the eyes when we focus on NEARBY objects

Question 7

What is accommodation in terms of oculomotor cues?

Answer 7

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

Question 8

What are monocular cues?

Answer 8

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

Question 9

What are pictorial cues? are they monocular or bionocular?

Answer 9

• monocular
• sources of depth information that comes from 2D images (e.g. pictures)

Question 10

What is occlusion? Is it a monocular or binocular cue?

Answer 10

• monocular
• when one object partially covers another

Question 11

What kind of information does relative height give us? Is it a monocular or binocular cue?

Answer 11

• monocular
• objects BELOW the horizon that are HIGHER in the field of vision are more DISTANT
• objects ABOVE the horizon that are LOWER in the visual field are more DISTANT

Question 12

What is perspective convergence? Is it a monocular or binocular cue?

Answer 12

• monocular
• parallel lines appear to come together in the distance

Question 13

What is relative size? Is it a monocular or binocular cue?

Answer 13

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

Question 14

What is atmospheric perspective? Is it a monocular or binocular cue? Why does this occur?

Answer 14

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

Question 15

Why do farther objects tend to appear more blue?

Answer 15

our atmosphere preferentially scatters short wavelengths and looking ‘through’ more of it increases the ‘blueness’ (i.e. atmospheric perspective)

Question 16

What is texture gradient? Is it a monocular or binocular cue?

Answer 16

• monocular
• equally spaced elements are more closely packed as distance increases

Question 17

How do shadows enhance depth? Is it a monocular or binocular cue?

Answer 17

• monocular
• indicates where objects/features are located

Question 18

What is motion parallax? Is it a monocular or binocular cue? Explain how it works in terms of the retina.

Answer 18

• monocular
• CLOSE objects in direction of movement glide RAPIDLY past, but DISTANT objects appear to move SLOWLY
• the image of something CLOSER to us travels LARGER DISTANCE across the retina, vs something farther away, in an equivalent amount of time

Question 19

What is deletion and accretion? Is it a monocular or binocular cue?

Answer 19

• monocular
• objects are covered or uncovered as we move relative to them
• deletion = covering an object
• accretion = uncovering an object

Question 20

Which of the following indicate relative depth:
- occlusion
- deletion and accretion
- motion parallax
- convergence
- relative size
- atmospheric perspective
- relative height
- texture gradients
- accommodation

Answer 20

• occlusion
• deletion and accretion
• relative height
• atmospheric perspective

Question 21

Which of the following indicate actual depth:
- occlusion
- deletion and accretion
- motion parallax
- convergence
- relative size
- atmospheric perspective
- relative height
- texture gradients
- accommodation

Answer 21

• relative size
• texture gradients
• motion parallax
• accommodation
• convergence

Question 22

Which cues are optimized for 0-2 meters?
- occlusion
- deletion and accretion
- motion parallax
- convergence
- relative size
- atmospheric perspective
- relative height
- texture gradients
- accommodation

Answer 22

• occlusion
• relative size
• motion parallax
• accommodation
• convergence

Question 23

Which cues are optimized for 2-20 meters?
- occlusion
- deletion and accretion
- motion parallax
- convergence
- relative size
- atmospheric perspective
- relative height
- texture gradients
- accommodation

Answer 23

• occlusion
• deletion and accretion
• relative height
• relative size
• texture gradients
• motion parallax

Question 24

Which cues are optimized for above 20 meters?
- occlusion
- deletion and accretion
- motion parallax
- convergence
- relative size
- atmospheric perspective
- relative height
- texture gradients
- accommodation

Answer 24

• occlusion
• deletion and accretion
• relative height
• atmospheric perspective
• relative size
• texture gradients

Question 25

What is stereoscopic depth perception? Is it a monocular or binocular cue?

Answer 25

• binocular
• constructed based on input provided to both eyes

Question 26

What depth cue is the basis for how 3D glasses typically work?

Answer 26

stereoscopic depth perception