PSYC 331 - Depth Perception

What are monocular cues?

Only require one eye

What are pictorial cues?

A monocular cue, most used in 2D art to give a sense of depth

What are binocular cues?

Require two eyes, cannot be used in 2D art

What are visual cues?

Can be monocular or binocular, based on visual information

What are oculomotor cues?

Based on movement and position of the eyes (physical cues)

What are the monocular depth cues?

Interposition, atmosphere, height, retinal size, texture gradients, linear perspective, blur, shadows

What is interposition?

if one object is occluding another then it’s in front of that object, good for order, does not tell us how far away something is

What is atmosphere?

Air scatters light to distant objects are fuzzy and have a blue tint

What is height?

Objects below the horizon that are higher in the field of vision are farther away, only works for objects on horizontal surfaces

What is retinal size?

When objects are equal size, the closer one will take up more of your visual field, must know size of object

What are texture gradients?

Equally spaced elements are more closely packed as distance increases - texture closer to you is more defined

What is a compression gradient?

Size of texture decreases with distance

What is a density gradient?

Density of texture increases with distance, more packed together

What is linear perspective?

Parallel lines appear to converge in a 2D image

What is blur?

Parts of an image that are farther away from our point of focus are blurred (some form the atmoshpere)

What are shadows?

Something of an object can fall on a surface or on other parts of the object, light usually comes from above so we can use these to determine depth

What are depth cues that require movement?

Optic flow and motion parallax

What is optic flow?

When objects move, they move alone, but when we move, everything appears to be moving

What is motion parallax?

Close objects in direction of movement glide rapidly past but objects in the distance appear to move slowly

What is accommodation?

An oculomotor cue based on change in shape of the lens via the ciliary muscle, used to determine depth

What are binocular depth cues?

Vergence, binocular disparity

What is vergence?

An oculomotor cue, our eyes move inward when we focus on objects nearby and we use this movement to determine distance

What is binocular disparity?

Each eye receives slightly different view of the world, using these differences to determine depth is called stereopsis

What is a horopter?

An imaginary circle that passes through the point of focus, objects that fall on this fall on corresponding points on the retina (0 disparity)

What is uncrossed disparity?

Objects viewed are beyond the horopter

What is crossed disparity?

Objects viewed are in front of the horopter

What is diplopia?

When there is a large amount of disparity, we see double images

What is a passive 3D tv?

Two images at once on the tv are polarized vertically and horizontally

What is a active 3D tv?

Electronic shutter glasses and flickering between the two images

What is a lenticular 3D tv?

Mini lenses on screen, no glasses needed, need to be pretty close up

What is a random-dot stereogram?

Randomly arranged dots with some dots shifted to the right, the dots are viewed using a stereoscope with rapid alternation on a computer screen, allows for the study if disparity without any other depth cues

What is stereopsis in the brain?

Nuerons have been found that respond best to binocular disparity

What are binocular depth cells?

Neurons that respond best to a specific degree of absolute disparity between images on the right and left retinas

What is the correspondence problem?

How does the visual system match images from the two eyes? - matches may be made by specific features of objects

What is stereoblindness?

A condition where an individual can’t see depth using binocular disparity, typically caused by a strabismus early in life

What is size perception?

size-distance invariance - size and distance depend on each other

What is size constancy?

Perception of an object’s size remains relatively constant, brain knows how big or small something should be, the changes in distance and retinal size balance each other out