Depth, Size and Shape

Question 1

What is Binocular Disparity?

Answer 1

DEF: the difference in the location of a feature between the right eye’s and left eye’s image.

Question 2

What does Binocular Disparity depend on?

Answer 2

Depends on:

Depth (the difference in distance to the 2 objec and the distance to the point of fixation)

Distance to the fixation, so that disparities must be further interpreted using estimates of the fixation distance.

Question 3

What is a horopter?

Answer 3

It’s an imaginary surface that passes through the point of fixation and indicated teh location of objects that falls on the foveas.

ZERO DISPARITY

Question 4

what is uncrossed disparity?

what is crossed disparity?

Answer 4

uncrossed- (diverge eyes to fixate on it) an object farther away from you than the horopter

crossed- (converge eyes to fixate on it) object closer than the horopter

Question 5

One way to view stereo image pairs is to use a mirror________. If you put your face in front of a pair of angled mirrors, and put two slightly different pictures off to the sides, your left eye will see the left picture and your right eye will view the right hand picture.

Answer 5

Stereoscope OR red-green anaglyph

Question 6

What important consequences does a a random dot stereogram have?

1.

2.

3.

Answer 6

1. You can see depth from binocular disparity without any other depth cue present (ex: motion parallax, perspective etc.)
2. You can see depth without extracting delineated form or a recognizable object. This implies that binocular combination is early. IT PRECEDES PROCESSING OF RECOGNIZABLE FORMS/ SHAPES/OBJECTS.
3. You can determine which dot in the left eye goes with which dot in the right eye in the presence of many potential false matches.

Question 7

Do people with Amblyopia have binocular vision or stereopsis?

Answer 7

NO because they never use both eyes at the same time.

Question 8

There is disparity selectivity in V1 when….

Answer 8

a line is shown to one eye at a time.

(To get a response the line must be shown 1.simultaneously to both eyes

2. have the correct orientation
3. direction of motion
4. correct binocular disparity)

Question 9

Why don’t we always see two views of the world?

Answer: the two images are combined in the brain to yield a single unified perceptual experience.

1. How do our eyes do this?
2. What happens when the disparity is too large that the neurons in the brain cannot cope with it to create a single vision?

Answer 9

1. FUSION- Panun’s fusional area is the range of disparities or equivalently the range of depths in 3D space on either side of the horoptor, over which the visual system can successfully fuse the two views.

2. Suppression, Diplopia (double vision) and Binocular Rivalry (The phenomenon of binocular rivalry is of particular interest in studying consciousness/visual awareness because the physical stimuli (the two gratings) do not change, yet the conscious percept changes dramatically over time. )

Question 10

Name all the monocular cues or pictorial depth cues.

1-12

12 (a-c)

Answer 10

• Familiar size- based on previous knowledge. EX: People are larger than quarters.
• Relative size- when two objects are of equal size, the one that is father away will take up less of VF than the one that is closer.
• Brightness cues-
• occlusion- an object occludes another one
• shading and shadows

* Shading and shadows

• Aerial perspective- when more distant objects appear less sharp and often have a slight blue tint.
• Linear perspective- when parallel lines extend out from an observer, they are perceived as converging as distance inceases.
• Height within an image-objects below horizon and higher in the VF are seen as more distant AND objects above horizon and lower in VF indicates more distant.
• Texture gradient- elelments that are equally spaced spaced in a scene appear to be more closely packed as distance increases
• Contours
• Accommodation and optical blur

• Motions cues:
a. Motion parallax- as we move, nearby objects appear to glide rapidly past us, but more distant objects appear to move more slowly.

b. Kinetic depth
c. Dynamic occlusion

Question 11

What are some binocular cues?

Answer 11

1. Convergence
2. stereopsis or binocular disparity

Question 12

What is an Ames room?

Answer 12

An Ames room is constructed so that from the front it appears to be an ordinary cubic-shaped room, with a back wall and two side walls parallel to each other and perpendicular to the horizontally level floor and ceiling. However, this is a trick of perspective and the true shape of the room is trapezoidal: the walls are slanted and the ceiling and floor are at an incline, and the right corner is much closer to the front-positioned observer than the left corner (or vice versa).

Question 13

What is the Epstein familiar size experiment?

Answer 13

Subjects are presented with a quarter and a dime in one the 2 coins look as they would if they were the same distance apart from the observer and therefore the dime looks smaller.

In the other part the observer is presented with a quarter and a dime that are the same size.

They are asked: How far away is the coin?

Observer inferes that in the second picture the dime must be closer because its the same size as the quarter.