# PSYB51H3 Study Guide - Binocular Disparity, Binocular Summation, Projective Geometry

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29 Mar 2014
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PSYB51- CHAPTER 6 β SPACE PERCEPTION AND BINOCULAR VISION
Euclidean: the geometry of the world. In here the parallel lines remain parallel when they are
extended in space, objects maintain the same size and shape as they move around in space, and
internal triangles add up to 180 degrees. However the retinal area occupied by an object gets
smaller as the object moves further away from the eyeballs. What this mean is that if we want to
appreciate the Euclidean world, we must reconstruct it from the non-Euclidean input (2D surface
of retina).
- The geometry of retinal images of that world is decidedly non-Euclidean
- The geometry becomes non-Euclidean when the three dimensional world is projected onto the curved,
two-dimensional surface of the retina
- Having two eyes is an evolutionary advantage β you can lose one and still see
- Having two eyes enable you to see more of the world
- Human visual field is limited to about 190 degrees from left to right, 110 degrees of which I covered by
both eyes
- Binocular visual fields give predator animals a better change to spot small, fast-moving objects in front
of them that might provide dinner
- Binocular: having two eyes
Binocular summation: the combination of signals from each eye that makes performance better vs one
eye.
Binocular disparity: the difference between the two retinal images of the same scene. Disparity is the
basis for stereopsis, a vivid perception of the 3D of the world that is not available with monocular vision.
Stereopsis is the ability to use binocular disparity as a cue to depth. A phase difference between the
two monocular gratings creates binocular disparity and some cells in the visual cortex is sensitive to this
phase shift.
Depth cue: information about the third dimension of visual space.
Monocular depth cue: a depth cue when the world is viewed with one eye
Binocular depth cue: a depth cue when the world is viewed with two eyes. Stereopsis is the primary
example in humans.
Occlusion: a cue to relative depth order, in which one object obstructs the view of another. Itβs a
nonmetrical depth cue.
Nonmentrical depth cue: a depth cue that tells us about the depth order but not he depth magnitude.
Metrical depth cue: tells us about the quantitative information about distance in third space.
Projective geometry: itβs a geometry that tells us about the changes that occur when the third
dimensional world is projected in to two dimensional surface. The parallel lines in 2d world can converge
Relative size: a comparison of sizes between items without knowing the absolute size of either one.
Texture gradient: a type of depth cue that us information about the items that are the same size form
smaller images when they are father away.
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## Document Summary

Psyb51- chapter 6 space perception and binocular vision. In here the parallel lines remain parallel when they are extended in space, objects maintain the same size and shape as they move around in space, and internal triangles add up to 180 degrees. However the retinal area occupied by an object gets smaller as the object moves further away from the eyeballs. What this mean is that if we want to appreciate the euclidean world, we must reconstruct it from the non-euclidean input (2d surface of retina). The geometry of retinal images of that world is decidedly non-euclidean. The geometry becomes non-euclidean when the three dimensional world is projected onto the curved, two-dimensional surface of the retina. Having two eyes is an evolutionary advantage you can lose one and still see. Having two eyes enable you to see more of the world.