binocular vision Flashcards
what is euclidian geometry?
parallel lines remain parallel as they are extended in place
are the images projected onto the retina euclidean?
no
how can euclidian geometry be explained?
objects maintain in the same size and shape as they move around space
whats binocular summation?
the combination of signals from each eye in ways that make performance on many tasks better with both eyes than with either eye alone
what is binocular disparity?
the differences between the two retinal images of the same scene
what is stereopsis?
a vivid perception of the three dimensionality of the world that is not available with monocular vision
what is a depth cue?
information about the third dimension of visual space
what is a monocular depth cue?
a depth cue that is available even when the world is viewed with one eye alone
what is a monocular depth cue?
a depth cue that relies on info from both eyes
what is a binocular depth cue?
a depth cue that relies on info from both eyes
what is occlusion?
a cue to relative depth order in which, one object obstructs the view of another
what is a metrical depth cue?
a depth cue that provides quantitative info about distance in the third dimension
what is a nonmetrical depth cue?
a depth cue that provides info about the depth order but not depth magnitude
what is relative size cue?
a comparison of size between items without knowing the absolute size of either one
what is relative height?
below the horizon, objects higher in the visual field appear further away. above, objects lower in the field appear to be further
what is texture gradient?
a depth cue based on the geometric fact that items of the same size form smaller images when they are further away
whats the cause of texture gradients?
results from a combination of the cues of relative size and relative height
what is familiar size?
a cue based on knowledge of the typical size of objects
what is aerial perspective?
a depth cue based on the implicit understanding that light is scattered by the atmosphere
what is the effect of the aerial perspective?
more light is scattered when we look through more atmosphere so more distant objects appear fainter and bluer
what is linear perspective?
lines that are parallel in the three dimensional world will appear to converge in a two dimensional image as they extend into the distance
what is the vanishing point?
the apparent point at which parallel lines receding in depth converge
what is the motion parallax?
images closer to the observer move faster across the visual field than images further away
what is accomodation?
the process by which the eye changes its focus
what happens when the eye accomodates?
the lens gets fatter as gaze is directed toward nearer objects
what is convergence?
the ability of the two eyes to turn inward, often used to focus on nearer objects
what is divergence?
the ability of the two eyes to turn outward, often used to focus on farther objects
what are corresponding retinal points?
a geometric concept stating that points on the retina of each eye where the monocular retinal images of a single object are formed are at the same distance from the fovea in each eye
what is binocular disparity?
the difference between the two retinal images of the same scene
what is the vieth muller circle?
the location of objects whose images fall on geometrically corresponding points on the two retinas
what is horopter?
the location of objects whose images lie on the corresponding points. surface of 0 disparity.
how are objects on the horopter seen?
as single images when viewed with both eyes
what is panum’s fusional area?
the region of space infront and behind the horopter, within which binocular single vision is possible
how are images seen when objects are closer or further away from the hotopter?
if they fall on noncorresponding points in the two eyes they are seen as two images
what is diplopia?
double vision
what happens if stimuli falls outside of panum’s?
if visible in both eyes it will appear diplopic
what is crossed disparity?
the sign of disparity created by objects in front of the plane of the horopter
how are images dispaced in front of the horopter?
displaced to the left in the right eye and to the right in the left eye
what is free fusion?
the technique of converging or diverging (uncrossing) the eyes in order to view a stereogram without a stereoscope
what is stereoblindness?
an inability to make use of binocular disparity as a depth cue
what is the correspondence problem?
in binocular vision, the problem of figuring out which bit of the image in the left eye should be matched with which bit in the right eye
what are ways to solve the correspondence problem?
- blurring the image
- uniqueness constraint
- continutity constraint
how does blurring the image help with correspondance?
leaves only the low spatial frequency info which reduces the number of features
how does uniqueness constraint help correspondence?
the observation of a feature in the world is represented exactly once in the retinal image
how does continuity constraint help correspondence?
the observation that except at the edges of objects, neighbouring points in the world lie at similar distances from the viewer
how do most binocular neurons respond best when the retinal images are on corresponding points?
with zero disparity
what is another way neurons respond best?
when similar images occupy slightly different positions on the retinas of the two eyes
what is binocular rivalry?
the competition between the two eyes for control of visual perception, which is evident when completely different stimuli are presented to the two eyes
what is forced perspective?
when near and far objects are carefully aligned so that they appear to be interacting with eachother
