Chapter 10 - Lecture Section 10.1 Flashcards
What is a key challenge in perceiving depth?
A key challenge in perceiving depth is that we operate in a 3D world, different objects are different distances from us, and different distances from each other, but all of the visual information we are obtaining about those objects is coming from a 2d retinal image.
What are Oculomotor Cues?
Oculomotor Cues are the sensation of eye position and accommodation
What are Monocular Cues?
Monocular Cues require only one eye
What are Binocular Cues?
Binocular Cues mean depending on two eyes
Our perception of Depth from a 2D retinal image is based on ___.
Depth Cues
Ocular Cues can also be performed with ___ eye(s), so they are a kind of ___ Depth Cue.
one // Monocular
We feel the inward movement of our eyes using ___.
Proprioception
What is Proprioception?
Proprioception is body sense, where we can detect the position of our body using sensory signals from the muscles.
For a close object, there is a ___ amount of convergence, your eyes are pointing inwards towards your nose.
large
For a distant object, where your eyes are basically pointing forward, there would be ___ convergence.
less
Convergence is a ___.
Oculomotor Cue
Accommodation is a ___.
Oculomotor Cue
What is Accommodation?
In vision, bringing objects located at different distances into focus by changing the shape of the lens.
As an object moves ___, the Ciliary body contracts which allows the Lens to round. This is an example of ___.
closer // Accommodation
What is the tension you feel when you focus on your finger and bring it closer to your eye?
That is the Proprioceptive sense about what the muscles in your body are doing, and we can use this for depth information because the more accommodation, that means the closer the object will be.
The more Accommodation, the ___ the object will be.
closer
What are Pictorial Cues?
The type of cues that create the impression of depth from looking at pictures. This is the type of information that we obtain depth info from when we’re watching tv or looking at our phones.
Pictorial Cues are a ___ Cue.
Monocular
How did Renaissance artists create paintings with such a strong sense of depth?
Using Pictorial Cues
What is Occlusion (Overlap)?
When one object hides another object, the hidden object is perceived as farther away
Occlusion is a ___, ___ Cue
Monocular // Pictorial
Relative Height is a ___, ___ Cue
Monocular // Pictorial
For Relative Height, generally, it follows the rule that objects that are closer to where the horizon is in the picture, are perceived as ___.
farther away
For Relative Height, objects that are below the horizon, the object that is higher and closer to the horizon is perceived as ___. The object that is lower in the image is perceived as ___.
farther // closer
In Relative Height, for objects that are above the horizon, such as two clouds, the one that is closer to the horizon is perceived as ___. The cloud that is farther away from the horizon and higher up is perceived as ___.
farther away // closer
What is Familiar Size?
Familiar Size helps in judging distance based on prior knowledge of the size of objects.
Familiar Size is a ___, ___ Cue
Monocular // Pictorial
Kakes use of ___ about the size of familiar objects helps in judging the depth based on how the objects will change in size if they are closer or farther from you.
Top-Down information
How did Epstein (1965) measure subjects’ Familiar Size?
Epstein (1965) had subjects view either normal coins or pictures of coins that all had the same size, subjects closed one eye, using Monocular vision.
What did Epstein notice in the Dark-room condition, where coins were illuminated by spotlight?
Subjects perceived the Dime as the closest; the Nickel as far; and the Quarter as the farthest
Why did subjects perceive the Dime as the closest; the Nickel as far; and the Quarter as the farthest in the Dark-room conditions?
This is because if the Dime ends up being closer to you, it takes up a larger portion of your visual field, so people were using their understanding of how large dimes, quarters, and nickels usually are to get this percept. Its a fairly weak illusion though, because when you have a lit room, and you’re allowed to use 2 eyes, instead, you actually just perceive oddly sized coins that are all the same distance away.
What did Epstein notice in the Light-room condition, where coins were illuminated by spotlight?
Subjects perceived oddly sized coins that were all at the same distance away
Relative Size is a ___, ___ Cue
Monocular // Pictorial
What is Relative Size?
When two objects are of equal size, the farther object will take up less of your field of view
What objects does Relative Size not work on?
Relative Size doesn’t work for objects that you don’t have a good sense of their size
Example: Clouds, they could be any size and they don’t come in a consistent size.
What is an example of Relative Size?
You see two motorcycles driving down the road, you know that motorcycles are generally about the same size, so the object that takes up less of your field of view is perceived as farther away.
Perspective Convergence is a ___, ___ Cue
Monocular // Pictorial
What is Perspective Convergence?
Parallel lines converge as distance increases.
Which cue particularly applies to parallel lines?
Perspective Convergence
When the parallel lines are farther away from one another, that section of the road is ___, and when the lines are closer together, that is the portion of the road is ___.
closer // further away
Atmospheric Perspective is a ___, ___ Cue
Monocular // Pictorial
What is Atmospheric Perspective?
Atmospheric Perspective is a result of air (dust, H20 droplets, pollution) filters and scattering light. Therefore distant objects appear less sharp (lower contrast), and tinted blue.
A very distant object with a lot of air between the observer and the object is going to appear ___, in other words it will have lower contrast or be a little blurry, and it’s going to be slightly tinted ___.
less sharp // blue
A man is looking out over a forested coast, what does he notice about the colour of the trees?
The trees closest to the man are a deep, rich green, and there is a deep contrast for the shadowed part of the trees. But as he looks farther and farther out, he sees that they become lower contrast and slightly tinted blue.
Where might you not find Atmospheric Perspective?
Without atmosphere there would be no atmospheric perspective, so on the Moon this depth cue does not exist
Why can your Atmospheric Perspective be dependant on where you live?
Because the Atmosphere is different in different types of areas. Large cities have air that is dirtier, therefore thick and smoggy, whilst the air in the wilderness is more clean.
A man from the city who is used to smoggy air may see a mountain in a forest as being ___ than it really is because he is calibrated based on the Atmospheric Perspective he’s used to using in a smoggy city.
closer
Texture Gradient is a ___, ___ Cue
Monocular // Pictorial
What is Texture Gradient?
Textures appear more closely packed as distance increases
In order for a Texture Gradient cue to work, you have to be fairly familiar with what is making up the ___, so you know that it is a ___.
texture // consistent size
What types of things does Texture Gradient work on?
Texture Gradient works with groups of humans, flowers, and regular elements in the environment
Shadows are a ___, ___ Cue
Monocular // Pictorial
What do Shadows serve as?
Shadows can provide depth information about the position of a light source, but also depth within an image and depth within an object.
What is an example of Shadows at work in an environment?
Two pictures of the same mountain taken at different times of day can create different perceptions, where in the first image the angle of the sun is creating deep shadows and we can see the ridges and hills, and get a strong sense of depth of the different parts of this mountain. But in the second image, without shadows, the mountain looks quite flat and homogenous.
Shadow can ___ the position of different objects within a scene.
disambiguate
How do some artists create unique shapes only visible when viewed from the right/particular location (e.g. Felice Varini)?
Using knowledge of perspective, pictorial depth cues, and the Inverse Projection problem
They appear to violate regular depth coding.
Chalk artists often make use of ___ to provide the impression of depth to their work by laying the chalk down on the street in a distorted way to create the impression of depth.
pictorial depth cues
How does Motion work to create depth?
Motion works because as you move through the environment, you can look with just one eye and these motion cues are also gonna help you with depth perception.
Pictorial depth cues work when the observer is ___.
stationary
Motion is a ___ Cue.
Monocular
When the observer ___, even more depth cues are available.
moves
Motion Parallax is a ___, ___ Cue
Monocular // Motion
What is Motion Parallax?
When an observer moves, objects nearer to the fixation point/place they are looking at appear to move slower
To get a sense of ___ of the retinal image moving across the retina, we can calculate Velocity
speed
Velocity = ___?
Distance/Time
IDK if this is written entirely correctly, refer to slide titled “2. Monocular Cues (Motion)
“ An image that travels a large distance over the Retina as the observer moves down is perceived as a ___.
high Velocity
IDK if this is written entirely correctly, refer to slide titled “2. Monocular Cues (Motion)” An image that travels a shorter distance over the Retina as the observer moves down appears to be moving ___.
slower
For the Moving Observer - Motion Parallax follows the general rule that near objects appear to move ___.
faster
For the Moving Observer - Motion Parallax follows the general rule that near objects appear to move ___.
faster
For the Moving Observer - Motion Parallax follows the rule that when the observer fixates on the horizon, near objects move ___.
faster
For the Moving Observer - Motion Parallax follows the rule that when the observer fixates on an object (the object = stationary), other stuff that is closer moves in ___ direction as the observer.
opposite
For the Moving Observer - Motion Parallax follows the rule that when the observer fixates on an object (the object = stationary), other stuff that is farther moves in the ___ direction as the observer.
same
Questioning if this is correct, rewatch lecture In Motion Parallax, things that are very close to the fixation point, but are closer than the fixation point will move in the ___ direction as the observer.
opposite
Questioning if this is correct, rewatch lecture In Motion Parallax, stuff close to the fixation point is gonna move ___ and stuff far from the fixation point is gonna move ___.
slow // fast
Deletion/Accretion is a ___, ___ Cue.
Monocular // Motion
What is Deletion/Accretion?
This is when you are moving in the environment and you see two objects, one is occluding the other, and you move, changing the perspective.
What is Deletion?
When you are moving in the environment and you see two objects, one is occluding the other, and you move and the near object appears to block the view of the far object, this is referred to as Deletion.
What is Accretion?
When you are moving in the environment and you see two objects, the near one occluding the far one, and you move, uncovering the occluded far object, this is referred to as Accretion.
What is the purpose of Deletion/Accretion?
We can use Deletion/Accretion as a way of getting depth information because the thing that is being Deleted or Accreted is always further away, so it’s just occlusion, but with motion added to it.
Deletion/Accretion is the dynamic example of ___.
Occlusion
There is no ___ depth cue.
perfect
True or False: All depth cues work equally well
False. Some work at certain distances much better than others.
Which depth cue essentially always works?
Occlusion essentially always works because the object that’s covering another one is always closer
For ___ and ___, those proprioceptive signals are only good for large differences in the contraction of your muscles, so they are only good for 0-2 meters, and everything past that, the difference is so small that it becomes undetectable, only good for close up stuff.
Accommodation // Convergence
___ is a fairly reliable depth cue
Relative Size
Motion Parallax is good for things that are ___ to you, but when you have a very distant horizon in a very open setting, a high degree of openness, the things that are really far away appear to be moving so slowly relative to each other that they appear stationary.
fairly close
___ is only good for fairly distant things, not things that are right up close to you.
Relative Height
___ is only useful for very distant objects.
Atmospheric Perspective
Which depth cues are only effective for 0-2 meters in front of you?
Accommodation & Convergence
