How come we have two eyes but only see one of everything?
[ 2006-04-03 08:52 ]
 Having two eyes is certainly better than having
just one because two eyes provide us with stereo vision and
depth perception -- two things that just eye could not give
us.
With 2 inches separating our two eyes, each eye views an
object from a slightly different angle. For instance, if you
hold up a flower and look at it with just your right eye, the
image is different from the image of when you look at it with
just your left eye. The right eye sees more of the right side
of the flower while the left eye sees more of the left side of
the flower. If you placed the two different images on top of
one another, they would not match and our vision would be out
of focus. However, our brains sort out these varying visual
messages from our two eyes, combines the images, and the
recreates one three-dimensional image.
This is referred to as binocular vision. Just like
your look through two lenses in binoculars, humans view
the world through two lenses. The eyes of many other animals
are placed differently than ours. Many birds have an eye on
each side of their head. Each eye sees a completely separate
area stretching out on the left or the right.
Viewing the world through two eyes provides us with depth
perception. When you look at the flower through just one eye,
it looks a lot flatter. |
雙眼視覺
雙筒望遠鏡
| | |
|
