Chapter 6; Space Perception and Binocular Vision Flashcards
Realism
there is a real world to sense
positivism
all we really have to go on is the evidence of the senses, so the world might be nothing more than an elaborate hallucination
Euclidean
geometry of the world, knowing that things stay consistent: ex: parallel lines will eventually appear to merge. etc.
binocular disparity
the differences between the 2 retinal images of the same scene, basis for steropsis, a vivid perception of the 3-D of the world that is not available with monocular vision
stereopsis
the ability to use binocular disparity as a cue to depth
depth cues
info about the 3-D (depth) of visual space. Both in mono-binocular
occlusion
a cue to relative depth order in which, ex; one object obstructs the view of part of another object.
nonmetrical depth cue
a depth cue that provides info about the depth order (relative depth), but not magnitude (is nose is in front of his face).
metrical depth cue
a depth cue that provides quantitative info about distance in the third dimension
projective geometry
the geometry that describes the transformation that occur when the 3-D world is projected on to a 2-D surface. EX: parallel lines do not converge in the real world but they do in the 2-D projection of the world.
relative size
comparison of size between items without knowing the absolute size of either one.
texture gradient
depth cue based on the geometric fact that items of the same size form smaller images when they are further away. An array of items that change in size smoothly across the image will appear to form a surface tilted in depth
relative height
depth cue, the observation that objects at diff distance from the viewer on the ground plane will form images at diff heights in the retinal image. Object farther away will be seen higher in the image.
familiar size
a depth cue based on knowledge of the typical size of objects like humans or pennies
relative metrical depth cue
a depth cue that could specify, ex: object A is twice as far away as B without providing info about the absolute distance to either A or B.
absolute metrical depth cue
a depth cue that provides quantifiable info about distance in the 3-D (exact distance from nose to face).
aerial perspective (haze)
foggy/faintness = further away
linear perspective
parallel lines in the real world will eventually merge in 2-D image
vanishing point
point at which parallel lines will meet in 3-D (vanish)
pictorial depth cue
a cue to distance or depth used by artists to depict 3-D depth in 2-D pictures.
anamorphosis (anamorphic projection)
use of the rule of linear perspective to create a 2-D image so distorted that it looks correct only when viewed from a certain angle or with a mirror that counters the distortion
motion parallax
depth cue that is based on head movement. The geometric info obtained form an eye in 2 different positions at 2 different times is similar to the info from 2 eyes in different position in the head at the same time.
accommodation
eyes change it’s focus.
convergence
eyes turning inward
divergence
eyes turning outward
corresponding retinal point
a geometric concept that points on the retina of each eye where the monocular retinal image of a single object are formed are at the same distance from the fovea in each eye. The 2 foveae are also corresponding points.
crossed/uncrossed disparity
ex: one image in front of other, crossed = focused on back object, uncrossed = focused on front object.
stereoscope
device for simultaneously presenting 1 image to 1 eye and another to the other eye. Differences will give depth.
free fusion
the technique of converging (crossing) or diverging the eyes in order to view a stereogram without a stereoscope.
stereoblindess
inability to make use of binocular disparity as a depth cue. This term is typically used to describe people with vision in both eyes. Someone who has lost 1 or both eyes.
random dot stereogram (RDS)
stereogram made from a large number of randomly placed dots. Random dot stereogram contains no monocular cues to depth. Stimuli visible stereoscopically in random dot stereograms are Cyclopean stimuli.
Cyclopean
stimuli that are defined by binocular disparity alone (Random Dot Theory); requires disparity to see difference. Named after 1-eyed cyclops of homer’s odyssey.
correspondence problem
in binocular vision, the problem of figuring out which parts of the image goes to which eye.
unique constraint
in stereopsis, the observation that a feature in the world is represented exactly once in each retinal image. This constraint simplifies the correspondence problem.
continuity constraint
in stereopsis, the observation that, except at the edges of objects, neighboring points int eh world lie at similar distances from the viewer. This is 1 of several constraints that have been proposed to help solve the correspondence problem.
binocular rivalry
the competition between the two eyes for control of visual perception, which is evident when completely different stimuli are presented in both eyes.
stereoacuity
a measure of the mallets binocular disparity that can generate a sensation of depth.
dichoptic
each eye getting a entirely different image/stimuli
strabismus
crossed-eye
esotropia
crossed-eye; one eye points inward.
exotropia
crossed-eye; one eye points outward.
supression
the eye that is crossed sees an image it doesnt want.
