6 Depth Perception

Question 1

Q: How do people demonstrate accurate judgment of ambient distance in real-world scenes?

Answer 1

A: People demonstrate accurate judgment of ambient distance by surveying a scene, closing their eyes, and walking to a predesignated object, as shown in studies like Loomis et al. (1992).

Question 2

Q: Is there an innate element to depth perception?

Answer 2

A: The accuracy of depth perception suggests that there may be an innate element to it, although environmental factors also play a significant role.

Question 3

Q: What are oculomotor cues to depth perception?

Answer 3

A: Oculomotor cues to depth perception depend on sensing the position of our eyes and the tension in our eye muscles. This includes experiences such as convergence (eyes looking inward) and accommodation (lens bulging to focus on a near object).

Question 4

Q: How are the shape of the lens and the position of the eyes correlated with the distance of the observed object?

Answer 4

A: The shape of the lens and the position of the eyes are correlated with the distance of the observed object. These cues are effective at distances closer than 5-10 feet and become less effective for objects further away.

Question 5

Q: How does convergence change with the distance of the observed object?

Answer 5

A: The closer the object, the greater the convergence experienced. Convergence decreases as the distance to the object increases.

Question 6

Q: How does the eye accommodate for close vision?

Answer 6

A: For close vision, the eye accommodates by tightening the ciliary muscles, allowing the crystalline lens to become more rounded. This change in lens shape facilitates focusing on nearby objects.

Question 7

Q: What are pictorial cues to depth perception?

Answer 7

A: Pictorial cues are depth cues that can be depicted in a still picture and do not require viewing with both eyes. They are often better viewed monocularly and include several cues:

Overlap/Interposition/Occlusion
Relative size
Relative height
Atmospheric perspective
Linear perspective
Shading and shadow

Question 8

Overlap/Interposition/Occlusion:

Answer 8

This cue occurs when one object obscures part of another or overlaps with it.

Question 9

Relative Size:

Answer 9

Objects appear smaller on the retina as they get further away, even though they may look the same size at different distances.

Question 10

Relative Height:

Answer 10

Objects further away from the observer appear nearer to the horizon. If objects are below eye height, the highest object is furthest away, and if they are above eye height, the lowest object is further away.

Question 11

Atmospheric Perspective:

Answer 11

Distant objects appear less sharp and bluer due to scattering of light by the atmosphere. Familiar size can also be a cue to depth.

Question 12

Linear Perspective:

Answer 12

Parallel lines in the scene appear to converge as they get further away.

Question 13

Shading and Shadow:

Answer 13

Shadows within objects (attached shadows) and shading resulting from depth within an object provide cues to depth. The direction of the light source determines whether a surface appears depressed or elevated. Detached shadows, or shadows created by objects, can also provide depth cues.

Question 14

Texture Gradient:

Answer 14

Texture becomes smaller or finer as distance increases.

Question 15

What are motion-produced cues?

Answer 15

depend on movement of observer, or movement of objects in environment.

Question 16

Q: What is motion parallax?

Answer 16

A: Motion parallax occurs as the observer moves relative to a 3D scene. Nearby objects appear to move rapidly in the opposite direction of the observer’s movement, while far objects appear to move slowly.

Question 17

Q: Is motion parallax a monocular or binocular cue to depth perception?

Answer 17

A: Motion parallax is a monocular cue to depth perception.

Question 18

Q: How does motion parallax provide depth information?

Answer 18

A: The relative direction and amount of motion provide information about the depth of objects in the scene.

Question 19

Q: Which animals tend to utilize motion parallax more?

Answer 19

A: Motion parallax is utilized more by animals that do not have much binocular overlap in their visual fields.

Question 20

Q: What are some examples of motion parallax in action?

Answer 20

A: Examples include head bobbing and orthogonal running.

Question 21

Q: What are deletion and accretion?

Answer 21

A: Deletion and accretion are motion-produced cues to depth perception.

Question 22

Q: What happens during deletion?

Answer 22

A: Deletion occurs when one object moves in front of another, covering more of the background object.

Question 23

Q: What occurs during accretion?

Answer 23

A: Accretion occurs as one object moves away from another, revealing more of the background object as the foreground object covers less of it.

Question 24

Q: What is the binocular disparity cue?

Answer 24

A: Binocular disparity depends on the fact that slightly different images of a scene are formed on each eye.

Question 25

Q: What is another term for binocular disparity?

Answer 25

A: Binocular disparity is also called binocular stereopsis.

Question 26

Q: Who developed the stereoscope and pioneered the concept of 3D movies?

Answer 26

A: Charles Wheatstone (1802-1875) developed the stereoscope and pioneered the concept of 3D movies.

Question 27

Q: How does binocular disparity contribute to the perception of depth?

Answer 27

A: When the two eyes receive different images of the same scene, an impression of depth is experienced because for every point on one retina, there is a corresponding point on the other. Points that do not overlap create disparity.

Question 28

Q: How does the amount of binocular disparity help in depth perception?

Answer 28

A: The amount of disparity tells us how far objects are from each other. Less disparate images on the retina indicate objects that are closer together.

Question 29

Q: What percentage of people show stereo-blind performance and lack mechanisms for processing disparities?

Answer 29

A: Approximately 2-5% of people show stereo-blind performance and appear to lack mechanisms for processing disparities (Richards, 1971).

Question 30

Q: How does the cue of binocular disparity change with distance?

Answer 30

A: The cue for depth provided by binocular disparity diminishes with distance.

Question 31

Q: What is hyperstereo?

Answer 31

A: Hyperstereo can give increased depth perception from binocular disparity.

Question 32

Q: How did Julesz (1964) demonstrate the use of disparity information for depth perception?

Answer 32

A: Julesz (1964) showed that the visual system can use disparity information directly to generate a percept of depth.

Question 33

Q: How can a vivid sense of stereoscopic depth be created using binocular disparity?

Answer 33

A: To create a vivid sense of stereoscopic depth, the same image is presented to both eyes, but one is shifted slightly to the left or right. The shifted area appears to be displaced in depth, creating a 3D image called a stereogram.

Question 34

What are the 4 cues for depth perception?

Answer 34

occulomotor, pictorial, motion-produced, binocular disparity.