Unit 2.7 and 2.8 Binocular Depth Cues and Combinint Depth Cues

Question 1

What are binocular depth cues?

Answer 1

Binocular depth cues are depth cues that rely on information from both eyes, allowing for the perception of depth and three-dimensionality.

Question 2

What is binocular disparity?

Answer 2

Binocular disparity refers to the differences between the two retinal images of the same scene. It is crucial for depth perception and is the basis of stereopsis.

Question 3

What is binocular summation?

Answer 3

an advantage in detecting a stimulu that is afforded by having two eyes rather than just one.

Question 4

Why is binocular summation important?

Answer 4

Binocular summation is important because it increases the likelihood of detecting stimuli, improves depth perception, and enhances the overall visual experience by providing a richer and more detailed view of the environment.

Question 5

What are some limitations of binocular summation?

Answer 5

Limitations include potential visual conflicts if the images from both eyes are significantly different, which can lead to visual confusion or discomfort. Additionally, individuals with certain visual impairments may not experience the benefits of binocular summation effectively.

Question 6

How does binocular disparity contribute to stereopsis?

Answer 6

Binocular disparity provides the brain with depth information by comparing the slight differences in images from each eye, allowing for the perception of three-dimensionality (stereopsis).

Question 7

What is stereopsis?

Answer 7

Stereopsis is the perception of three-dimensionality created by the brain’s processing of the differences between the images from each eye, resulting in a vivid sense of depth.

Question 8

What are the processes of stereopsis?

Answer 8

1. selection of a depth surface (horopter) using vergence eye movements and accommodation
2. computation of binocular disparity, which provides depth information relative to the horopter

Question 9

What helps eyes perceive depth?

Answer 9

• accommodation: lens changes its focus
• convergence: the ability of the two eyes to turn inward; reduces the disparity of the feature to zero, or near zero
• divergence: the ability of the two eyes to turn outward; reduces the disparity of the feature to zero, or near zero.

Question 10

What is vergence?

Answer 10

Vergence is the ability of the two eyes to turn inward (convergence) or outward (divergence) to reduce the disparity of a visual feature to zero or near zero, aiding in depth perception.

Question 11

How does vergence contribute to depth perception?

Answer 11

Vergence provides motor input as a cue for depth by allowing the visual system to gauge the position of the eyes and the status of the ocular muscles, which helps in understanding the spatial arrangement of objects.

Question 12

What is the role of the efferent copy of the motor signal in vergence?

Answer 12

The efferent copy of the motor signal is a copy sent to the visual system that helps it understand what the eyes are supposed to be doing, allowing for adjustments based on the actual status of the eyes.

Question 13

What are corresponding retinal points?

Answer 13

Corresponding retinal points are points on the retinas of each eye where the monocular images of a single object are formed at the same distance from the fovea in each eye, crucial for achieving binocular vision.

Question 14

What is the horopter?

Answer 14

The horopter is the surface in three-dimensional space where objects’ images lie on corresponding retinal points, creating a surface of zero disparity.

Question 15

What is the difference between crossed and uncrossed disparity?

Answer 15

• Crossed Disparity: Occurs when an object is in front of the horopter; images are displaced to opposite sides on the retinas.
• Uncrossed Disparity: Occurs when an object is behind the horopter; images are displaced to the same side on the retinas.

Question 16

How does the visual system use absolute and relative disparity?

Answer 16

Absolute disparity refers to the actual difference in retinal coordinates of an image in each eye, used for controlling convergence.
Relative disparity compares the absolute disparities of two elements in the scene, providing information about their relative depth.

Question 17

What is the significance of depth cues in relation to vergence?

Answer 17

Depth cues, including vergence, help the visual system interpret the spatial arrangement of objects, allowing for accurate perception of distance and depth in the environment.

Question 18

What is a stereoscope?

Answer 18

A stereoscope is a device for presenting one image to one eye and another image to the other eye, creating a single, three-dimensional perception.

Question 19

How does a stereoscope create a 3D effect?

Answer 19

It delivers two slightly different images to each eye, mimicking the way human eyes perceive depth through binocular disparity.

Question 20

What are the technologies used for 3D viewing in electronic devices?

Answer 20

• Active 3D
• Passive 3D
• Autostereoscopic 3D
• Headsets

Question 21

Describe Active 3D technology.

Answer 21

Active 3D technology alternates images for the left and right eye, using active shutter glasses that sync with the display to block each eye’s view in turn. It is commonly used in some 3D TVs and operates at 120 Hz.

Question 22

Explain Passive 3D technology.

Answer 22

Passive 3D technology displays images for both eyes simultaneously using differently polarized light. Cheap passive glasses with polarization filters separate the images for each eye, and this technology is used in some 3D TVs and 3D cinema, such as IMAX.

Question 23

What is Autostereoscopic 3D technology?

Answer 23

Autostereoscopic 3D does not require headgear. It uses techniques like parallax barriers or lenticular arrays to project alternating columns of pixels into each eye, allowing for 3D viewing without glasses. Examples include the Nintendo 3DS and flat 3D laptop screens.

Question 24

How do Virtual Reality headsets work in 3D technology?

Answer 24

Virtual Reality headsets typically use smartphones with special optics to show separate images to each eye, creating an immersive 3D experience. They are available from various commercial manufacturers.

Question 25

What is Free Fusion in the context of binocular vision?

Answer 25

Free Fusion is the technique of converging or diverging the eyes to view a stereogram without a stereoscope. It involves adjusting focus to see overlapping blurred images clearly.

Question 26

Define Random Dot Stereogram (RDS).

Answer 26

A Random Dot Stereogram is made of randomly placed dots that contain no monocular cues to depth. The depth perception arises solely from binocular disparity, creating cyclopean stimuli.

Question 27

What is cyclopean?

Answer 27

it refers to the stimuli that are defined by binocular disparity alone

Question 28

What is the Correspondence Problem in binocular vision?

Answer 28

The Correspondence Problem refers to the challenge of determining which parts of the image in the left eye correspond to parts in the right eye, essential for depth perception.

Question 29

Why is the Correspondence Problem complex in real-world images?

Answer 29

In complex images, multiple objects and varying depths can create numerous potential matches between the images seen by each eye, making it difficult to determine which features correspond to the same object.

Question 30

What are some ways to solve the correspondence problem?

Answer 30

1. blurring the image: leaving only the low-spatial frequency information (reduces the number of blobs to match)
2. uniqueness constraint: a feature in the world will be represented exactly once in each retinal image
3. continuity constraint: except at the edges of objects, neighbouring points in the world lie at similar distances from the viewer

Question 31

What role do binocular neurons play in stereopsis?

Answer 31

Binocular neurons in the brain respond to input from both eyes, allowing for the perception of depth through the comparison of images. They are tuned to respond to corresponding points in the retinas and to specific binocular disparities.

Question 32

What is Binocular Rivalry?

Answer 32

Binocular rivalry occurs when different stimuli are presented to each eye, leading to competition for visual perception. This can result in one image being suppressed while the other is perceived, highlighting the complexity of visual processing.

Question 33

What is the Bayesian approach in the context of depth perception?

Answer 33

The Bayesian approach is a statistical model that suggests prior knowledge can influence estimates of the probability of a current event, helping the visual system to determine the most likely interpretation of visual information.

Question 34

What is an “ideal observer” in the context of depth perception?

Answer 34

An ideal observer is a theoretical observer with complete access to the best available information and the ability to optimally combine different sources of information to make accurate judgments about depth.

Question 35

What are depth illusions, and how do they arise?

Answer 35

Depth illusions occur when there are conflicts between different depth cues, leading to misinterpretations of size or distance, such as the Ponzo illusion, where two horizontal lines appear to be different lengths due to perceived depth.

Question 36

What is the Ponzo illusion?

Answer 36

he Ponzo illusion is a visual illusion where two horizontal lines appear to be of different lengths when placed between converging lines, such as railroad tracks. The top line appears longer than the bottom line due to the depth cues provided by the converging lines.

Question 37

How does the Ponzo illusion work?

Answer 37

The illusion works by utilizing the brain’s interpretation of depth. The converging lines create a perspective that suggests the top line is farther away, leading the brain to perceive it as longer than it actually is.

Question 38

What depth cue is primarily involved in the Ponzo illusion?

Answer 38

The primary depth cue involved is linear perspective, which gives the impression of depth and distance.

Question 39

What are accidental viewpoints?

Answer 39

Accidental viewpoints refer to specific angles or perspectives that can create misleading perceptions of spatial relationships or object sizes due to the alignment of visual elements.

Question 40

How do accidental viewpoints lead to illusions?

Answer 40

They lead to illusions by causing the observer to make erroneous assumptions about the contiguity of objects, resulting in misperceptions of depth or size. For example, two objects may appear to be connected or aligned when viewed from a particular angle, creating a false impression of their spatial relationship.

Question 41

What is the Ames room?

Answer 41

The Ames room is a distorted room designed to create optical illusions of size and distance. It appears rectangular from a specific viewpoint but is actually constructed in a trapezoidal shape.

Question 42

What is the significance of the Ames room in studying perception?

Answer 42

The Ames room demonstrates how context and perspective can dramatically alter our perception of size and distance, highlighting the role of depth cues in visual perception.

Question 43

What is stereo acuity?

Answer 43

Stereo acuity is a measure of the smallest binocular disparity that can generate a sensation of depth. It reflects the ability to perceive depth based on the differences between the images received by each eye.

Question 44

What does “dichoptic” refer to in vision?

Answer 44

“Dichoptic” refers to the presentation of two stimuli, one to each eye. This differs from binocular presentation, where both eyes view a single stimulus.

Question 45

At what age is stereopsis typically detected in infants?

Answer 45

Stereopsis is typically detected at around 3 to 4 months of age.

Question 46

What is the critical period in the development of stereopsis?

Answer 46

The critical period is a time when the organism is particularly susceptible to developmental changes. Abnormal visual experiences during this period can disrupt binocular vision.

Question 47

What is strabismus, and how does it affect stereo acuity?

Answer 47

Strabismus is a misalignment of the two eyes, causing different images to be sent to each eye. This can hinder the ability to combine these images for depth perception, making stereo acuity difficult.

Question 48

What are the two types of strabismus mentioned?

Answer 48

The two types of strabismus mentioned are esotropia (where one eye deviates inward) and exotropia (where one eye deviates outward).

Question 49

How is stereo acuity often tested?

Answer 49

Stereo acuity is often tested using dichoptic stimuli, which present different images to each eye to assess the ability to perceive depth.

Question 50

What is the relationship between stereo acuity and binocular disparity?

Answer 50

Stereo acuity relies on binocular disparity, which is the difference in images seen by each eye. The brain uses these disparities to calculate depth perception.

Question 51

What are some developmental conditions that can affect stereo acuity?

Answer 51

Conditions such as strabismus, where the eyes are misaligned, can disrupt the normal development of stereo acuity, leading to difficulties in depth perception.