Section 4 Flashcards
What does it mean for the three dimensional world to be Euclidean?
It respects a set of basic geometrical rules, such that size, shape, and relative coordinates of objects remain constant when viewed at different distances
What is Euclidian geometry?
Objects remain the same size and shape as they move around in space
What are the two main ways our visual system infers the third dimension?
- monocular clues
2. binocular cues
What are the two main monocular depth cues?
Pictorial and movement-based cues
List all the pictorial cues
- occlusion
- relative size
- familiar size
- relative height
- texture gradient
- linear perspective
- aerial perspective
- shadows
What is the difference between a non-metrical and metrical depth cue?
A non-metrical depth cue cannot tell you anything about the relative or absolute distance between two objects, whereas a metrical depth cue can
Which pictorial cue is an absolute metrical depth cue?
Familiar size
How does relative height work?
Objects that appear higher in the visual field tend to be perceived as being further away
When do we experience the greatest feeling of distance between us and an object?
When the object is parallel to the ground
How does linear perspective help us capture the third dimension?
By relying on the idea that objects become smaller and closer to each other as they recede in space
What is a vanishing point?
The apparent point at which parallel lines receding in depth converge
Which combination of pictorial cues generates linear perspective?
relative size and relative height
What is the ponzo illusion?
When two parallel lines extend into the distance, our visual system makes us think they are converging together. If you place an object at two different points along these converging lines, because the further lines look smaller and closer together it will make the object placed further look bigger
How do shadows infer the third dimension?
If the shadows of objects are at different distances in the visual field, then the objects will also look to be at different differences
How do objects appear if their shadows are aligned?
It will look like the objects differ in height but not distance
How does motion parallax work?
It triggers the perception of depth based on the perceived translational movement of objects
How does optic flow work?
Allows the perception of objects while looking at where you are headed to
What is the focus of expansion?
The fixation point at the horizon from which the world seems to expand or vanish as you go forward or backwards, respectively
What two muscle groups send sensory feedback to your brain as you adjust your focus point?
Ciliary muscles and extraocular muscles
What information do the ciliary muscles send to the brain?
informs on the level of accommodation required to focus the image on the retina
What information do the extraocular muscles send to the brain?
informs on the level of vergence
Nearing objects cause _____ (convergence/divergence) of the eyes to keep the fixated object at the center of both retinas, whereas fixating a far away object increases eye _______ (convergence/divergence)
Convergence, divergence
TRUE/FALSE
Unlike most pictorial cues, oculomotor cues provide us with unambiguous information about absolute depth
true
What is stereopsis?
The rich impression of depth that we get from seeing with both eyes