Download Receptive field—How does the voting happens

Monocular vs. Binocular View
Monocular view: one eye only! Many
optical instruments are designed from one
eye view.
Binocular view: two eyes with each seeing
a separate picture of the world.
Increase the field of view: fish, rabbits can see
360.
Overlapping view: predators with two eyes in
the front.
Human eyes
Separated by ~ 6.5 cm.
Have field of view ~ 208˚.
Overlapping view ~ 130˚.
Each eye sees a slightly different view.
Your brain combines the two images into
one view of the world! (mixing of signals in
the optical chiasma and visional cortex)
2-D vs. 3-D world
A picture is a 2D reduction of the 3D world.
How do we appreciate 3D?
We use many different cues (a feature
indicating the nature of something perceived)
Accommodation
Convergence
parallax
Accommodation
The amount of accommodation necessary
to focus your eye on an object tells you the
object’s distance.
See the object clearly with a relaxed eye: it is
far away.
Tense your eye muscles to focus, it is close by..
It is only useful, however, to measure
distances for close objects.
Angle of convergence
The angle between two eyes’ directions
of gaze.
For object close by, say 25cm. It is the biggest,
about 15 degree.
It is 1 degree for an object 4m away.
If the brain keeps track of the convergence
of eyes, it can determine the distance to
the object. (help to distinguish a painting from
a real scene!)
Parallax
Your view is different from different
positions.
Viewing something from two different
perspectives causes it to seem to move
between two positions, at least compared to
its background
Has been used by astronomers to
determine the distances of the stars from
us.
 The first parallax shift of a star was detected
in 1838 by an astronomer named F. W.
Bessel, at the Konigsberg Observatory in
Prussia. The star was actually a binary called
61 Cygni, a gravitationally bound pair of red
dwarf stars. Bessel found that these stars
were making annual loops with a radius of
.29 arcseconds, corresponding to a distance
of 10.3 lightyears (in other words, the
distance light would travel in 10.3 years!).
 What's an arcsecond, It's a sixtieth of an arcminute, of course,
which is a sixtieth of a degree. A degree is about the width of
your thumbnail, held at arm's length. It's not surprising that
earlier astronomers had such a hard time detecting such a tiny
shift!)
Binocular Disparity
Two eyes, at different positions at the
same time, see slightly different views of
the any object they look at.
The binocular disparity provides a way of
determining the distance of the object in
sight.
Because the eye are fixated on the tree, the
tree is imaged on corresponding points of
the retina (those points that would be identical if
one retina was moved over to superimpose the
other retina) and thus there is no disparity.
The policeman, who is closer to the
observer, has its image falling on noncorresponding points of the retinas. That is
to say its images are binocular disparate.
This binocular disparity provides a cue to
the distance of the policeman relative to the
distance of the tree.
Where could it fail?
If the two eyes see the same image:
Two examples
horizontal power lines!
objects that repeat themselves (bars in a cage)
Distant scenes.
Stereoscope
Stereoscope
Create 3-D images!
Present two different pictures to the two eyes
so that each eyes sees only the image intended
for it.
How to create them?
Two cameras side by side
Moving a camera slightly
Superimposed 2D pictures
Use color filters:
Two similar pictures with different colors are
superimposed (anaglyph). Viewers are given a
different color filter for each eye.
Use polarization
Two similar pictures are projected with light of
different polarizations (horizontal or vertical)
Viewers are given a special pair of glasses with
polarization filters. (3D movie)
Stereogram