Depth Perception

Question 1

What is a pictorial depth cue?

Answer 1

A cue used to depict 3D depth in 2D pictures.

Question 2

What is occlusion?

Answer 2

Occlusion is a depth cue that gives us information about the relative position of objects. It is used to describe the situation where an object or part of an object is blocked by another object.

Question 3

What type of depth cue is occlusion?

Answer 3

Occlusion is a non-metric depth cue

Question 4

Non-Metric Depth cue

Answer 4

Gives us information about the depth order (relative depth) but not the depth magnitude (e.g., his nose is in front of the face).
examples: relative size, texture gradient, interposition, and linear perspective.

Question 5

What is a metrical depth cue?

Answer 5

A metrical depth cue provides us with information about distance and depth of objects (e.g stereopsis)

Question 6

What does projective geometry describe?

Answer 6

Projective geometry describes how the world is projected onto a surface.

Question 7

What are texture fields?

Answer 7

Texture fields are patterns or textures that give the impression of depth or three-dimensionality.

Question 8

What are textural fields a combination of?

Answer 8

Texture fields that appear three-dimensional are actually a combination of relative size and relative height cues

Question 9

What is familiar size as a depth cue?

Answer 9

Depth cue based on the knowledge of the typical sizes of objects such as humans or pennies

Question 10

Absolute metrical depth cue

Answer 10

A depth cue that provides quantifiable information about distance in the 3D world.

Question 11

Is familiar size an absolute metrical depth cue?

Answer 11

Familiar size could be an absolute metrical depth cue, which is a depth cue that provides quantifiable information about distance in the 3D world.

Question 12

Difference between monocular and binocular cues

Answer 12

Binocular cues require two eyes to perceive depth, while monocular cues can be perceived with just one eye.

Question 13

Triangulation Cues:

Answer 13

Refers to the triangle formed by the two eyes and the point on which they fixated in the 3D world.

Question 14

What are the two main types of triangular cues?

Answer 14

1) Monocular (motion parallex and focus)
2) Binocular (Convergence and Stereopsis)

Question 15

What is motion parallax?

Answer 15

Depth cue that is based on head movement. It is a visual phenomenon that occurs when we move our head or body and the objects in our environment appear to move at different rates.

Question 16

What does motion parallax allow?

Answer 16

1) Allows us to see the world from multiple viewpoints at different times by moving our head.
2) It also provides relative metrical information about how far away objects are.

Question 17

What is optic flow?

Answer 17

Visual phenomenon that occurs when we move through our environment, causing the visual world to appear to move around us.

Question 18

What is convergence?

Answer 18

A phenomenon that occurs when our eyes move inwards towards each other, allowing us to focus on objects that are close to us.

Question 19

The closer the object is to our eyes, the more our eyes must_______ in order to focus on it.

Answer 19

converge

Question 20

What is divergence?

Answer 20

Divergence is the ability of the two eyes to turn outward to focus on objects that are far away.

Question 21

As we shift focus from a near to far point, our eyes ________.

Answer 21

diverge

Question 22

What is binocular disparity?

Answer 22

Binocular disparity refers to the differences between the images falling on our two retina.

Question 23

What is stereopsis?

Answer 23

The ability of our brain to perceive depth or three-dimensional (3D) information from the slightly different images captured by our two eyes.

Question 24

What is absolute disparity?

Answer 24

The distance between an object’s position in the left eye and its position in the right eye. When an object is closer to us, its absolute disparity will be larger than when it is farther away.

Question 25

What are relative disparities?

Answer 25

Relative disparities are the difference in the absolute disparities of two objects.

Question 26

What are corresponding retinal points?

Answer 26

Corresponding retinal points are the points on the retina of each eye that line up with the same location in visual space.

Question 27

What is the Vieth-Müller circle?

Answer 27

The Vieth-Müller circle is an imaginary circle that passes through the two eyes and the object being fixated.

Question 28

Objects lying on the Vieth-Müller circle project images onto _________, with ____

Answer 28

corresponding retinal points, zero binocular disparity.

Question 29

What is the horopter?

Answer 29

The horopter is the surface of zero disparity that runs through the point where both eyes are fixated. Any object placed on the horopter will form images on corresponding retinal points.

Question 30

What determines the position of the horopter in the world?

Answer 30

The position of the horopter in the world depends on the current state of convergence of the eyes.

Question 31

What happens to the disparity and depth of an object as the disparity increases?

Answer 31

The larger the disparity, the greater the distance in depth of the object from the horopter.

Question 32

What happens to an object that is significantly closer or farther away from the horopter?

Answer 32

Objects significantly closer or farther away from the horopter form non-corresponding images in the two eyes. These images do not fuse and result in diplopia, or double vision.

Question 33

What are the lower limits of stereopsis?

Answer 33

The lower limits of stereopsis are the smallest disparities that can be detected, which occur just to either side of the horopter.

Question 34

What happens beyond Panum’s fusional area?

Answer 34

Beyond Panum’s fusional area, objects will appear double or diplopic, meaning they will not fuse into a single image.

Question 35

Can relative depth still be perceived when objects are diplopic?

Answer 35

Yes, even when objects are diplopic, relative depth can still be perceived.

Question 36

What is the difference between quantitative and qualitative depth information provided by stereopsis?

Answer 36

Within a certain range of disparities, stereopsis provides quantitative depth information, meaning the relative depth of objects can be accurately estimated. As disparities increase beyond this range, stereopsis provides qualitative depth information, meaning objects can only be distinguished as being in front or behind, without an accurate estimate of their relative depth.

Question 37

What is the upper limit of stereopsis?

Answer 37

Once disparities exceed the upper limit of stereopsis, there is no longer any useful depth information provided by stereopsis.

Question 38

What is a stereoscope?

Answer 38

A stereoscope is a device that helps you see pictures in 3D

Question 39

What is crossed disparity?

Answer 39

Refers to the displacement of images of objects located in front of the horopter to the left in the right eye and to the right in the left eye.

Question 40

What is uncrossed disparity?

Answer 40

Uncrossed disparity refers to the displacement of images of objects located behind the horopter to the right in the right eye and to the left in the left eye.

Question 41

What is stereoblindness?

Answer 41

Stereoblindness is a condition in which a person is unable to perceive depth and three-dimensional images using stereopsis, which is the process of combining slightly different images from each eye to create a single image with depth.

Question 42

What is the correspondence problem?

Answer 42

The correspondence problem is a challenge that arises when our brain tries to match the images seen by each eye in order to create a single, three-dimensional image.

Question 43

What is the continuity constraint?

Answer 43

The continuity constraint is a principle that states that neighboring points in each eye’s image are likely to correspond to neighboring points in the other eye’s image. Our brain uses this constraint to fill in gaps in the correspondence between the two images and create a smooth and coherent 3D image.

Question 44

Where does the convergence of input from both eyes happen for stereopsis to occur?

Answer 44

The convergence happens in the primary visual cortex (V1), where most neurons are binocular.

Question 45

What are binocular neurons?

Answer 45

Binocular neurons have two receptive fields, one in each eye.

Question 46

Metrical stereopsis

Answer 46

Metrical stereopsis involves the precise calculation of the distance between objects in the visual scene.
- Often used to judge distances in 3D space, such as when reaching for objects.

Question 47

nonmetrical Stereopsis

Answer 47

Ability to perceive the overall layout of a scene and relative distances between objects without necessarily being able to make precise calculations of distance.

Question 48

What is the role of the dorsal where pathway in stereopsis?

Answer 48

The dorsal where pathway is most interested in metrical stereopsis, which provides precise depth information.

Question 49

What is the role of V2 in stereopsis?

Answer 49

Neurons in V2 are sensitive to relative disparities, which provide the basis for fine stereoacuity.

Question 50

What is the role of V4 in stereopsis?

Answer 50

Visual area V4 is involved in computing depth intervals

Question 51

What is the role of inferotemporal cortex in stereopsis?

Answer 51

Higher cortical areas, such as inferotemporal cortex, are involved in the representation of complex three-dimensional shapes.