Problem 5: Depth perception Flashcards
binocular disparity
difference in image between two eyes (stereoscopic vision is the basis for disparity)
what are corresponding points
when looking at an object, the image is at relatively the same location in both eyes, allowing you to see it as one object
what is the horopter
imaginary surface on which corresponding points lie
what is absolute disparity
degree to which an image deviates from a corresponding point (changes with every new fixation, the difference in space between the objects on your retina)
what is relative disparity
stays the same between two objects in your visual field (the difference in actual space between the objects)
uncrossed and crossed disprity
crossed: when an object is in front of the horopter (your eye’s need to cross to focus on it)
uncrossed: behind the horopter (your eyes need to uncross to focus on it)
correspondence problem + possible answer
how come two images become one in our mind
- our visual system would line up the common features in the two retinal images ( does not hold up with stereograms)
what are binocular neurons / disparity selective cells
neurons that best respond to a certain amount of absolute disparity
experiment on depth perception
stereopsis: trying to prove disparity, creating a 3D image without using any depth cues except from disparity
Pictorial monocular cues
- occlusion: overlapping
- relative height: height relative to horizon
- relative size: when two objects are of equal size, the one that appears smaller is further away
- familiar size: helps us determine size of objects
- perspective convergence: parallel lines further away seem to converge
- atmospheric perspective: things further away seem blurrier and bluer
- texture gradient: when you know elements are equally spaced, the ones more packed are further away
- shadows: give information about object location
motion-produced monocular cues:
- motion parallax (closer objects move by faster)
- deletion (when an object is covered as a result of movement)
- accretion (when an object is uncovered as a result of movement)
accommodation
change in the shape of lens when you focus at different points
convergence
your eyes moving inwards when you focus on something close
convergence
your eyes moving inwards when you focus on something close
visual angle
determines the size of an image on the retina (a small object that is near can have the same size on the retina as a large object that is far away)
holway and boring experiment:
one hallway with a comparison circle and one with a circle that changes
in phase 1: depth cues are available
phase 2: depth cues are absent
–> when all depth cues are eliminated they started comparing the size of the circles to the sizes of the previously seen circles, because no depth information was available
size perception and constancy formula
S = K (R * D)
S = perceived size
K = scaling factor
R = retinal image size
D = perceived distance
myers-lyer arrow illusion:
explanation: the fins are outer and inner corners of a room, which would influence our perception –> doesn’t hold
explanation: conflicting cues theory: perception depends on the actual cue of the line + the overal length of the figure
moon illusion:
apparent distance theory: the horizon has depth cues, the sky has no depth cues
Angular size contrast theory: moon appears smaller when there’s a lot of empty sky around it
