W6 - Depth perception ✅

Question 1

What are 4 cues to depth?

Answer 1

1. Oculomotor cues:
2. Monocular cues (pictorial)
3. Motion-produced cues:
4. Binocular disparity:

Question 2

What is meant by oculomotor cue?

Answer 2

sense the change in lens due to different distances of objects (only effective with close objects)
- convergence: direction of both eyes
- accommodation: change in lens thickness
-> contract (close), relax (far)

Question 3

What is meant by monocular cue (pictorial)?

Answer 3

information that can be perceived by one eye alone, including:
- relative size: smaller object is further away
- overlap/interposition
- linear perspective: parallel lines converge as it gets further away
- relative height: further away = nearer to the horizon
- atmospheric perspective: distant objects appear less sharp (also appear more blue)
- familiar size: knowledge-based context
- shading and shadow (assume direction of lighting from above): imply location of object from ground surface
- texture gradient: smaller and less detailed as distance increases

Question 4

What is meant by motion-produced cue?

Answer 4

cues that depend on movement of the observer or objects in the environment (e.g. object moving closer appears larger)
- motion parallax: nearby objects appear to move rapidly and vice versa
- deletion: front object cover more of the back object as it moves in front of the other
- accretion: front object cover less of the back object as it moves away

Question 5

What is meant by binocular disparity?

Answer 5

cues from different images being perceived on the left and right eyes.

Explanation: corresponding retinal points
- more disparity in the retinal images when object is closer to observer
- this cue diminishes with distance

Question 6

What is meant by size constancy?

Answer 6

Retinal image size changes with distance
- Increase distance = decrease retinal image size
- Decrease distance = increase retinal image size

-> Size constancy: an object can look the same size regardless of changing retinal image size

Question 7

What is Emmert’s Law

Answer 7

If retinal images of 2 objects at different distance are the same size then:
1. Object of constant size will get smaller retinal images as its distance from observer increases
2. The physical size of the object that’s farther away must be larger than the one that is closer.

Question 8

What is meant by stereogram?

Answer 8

A 2D image that, when viewed through a stereoscope or with the use of crossed or uncrossed eyes, appears as a 3D image with depth and volume.

Created by presenting slightly different images to each eye, which creates the illusion of depth and solidity.