Binocular vision

[scilearner]

Hello everyone,

 

If we have 2 eyes how come we don't see 2 objects. Then I found the answer was binocular vision, and both eyes concentrate on the same spot. Now my question is does the brain make the 2 different angles into one object or it always happens? I mean does something have to be done from the brain to merge these 2 views? Also I would like to know more about how the different view merge. Thanks

[Mr Skeptic]

Here's something you should try. Hold your index fingers horizontally, a few inches from your eye, and then move them together. Focus your eyes on something farther away even though the fingers are in the middle of your field of vision. What do you see?

[scilearner]

Here's something you should try. Hold your index fingers horizontally, a few inches from your eye, and then move them together. Focus your eyes on something farther away even though the fingers are in the middle of your field of vision. What do you see?

 

Hey thanks skeptic I did see 2 images then. I think then if both eyes look at the same spot, it is possible to easily merge the two angles into one picture. However I suppose the brain has evolved to do this. A simple yes or no would be nice. What I'm thinking is their some physics principle that if two different angles concentrate on the same spot, they add up, or has the brain evolved to do this? Thanks

[Double K]

The two seperate images is actually what gives us depth perception...very useful tool for predators when hunting

 

"depth perception,

the ability to judge depth or the relative distance of objects in space and to orient one's position in relation to them. Binocular vision is essential to this ability. Also called stereopsis"

 

http://medical-dictionary.thefreedictionary.com/Visual+depth+perception

[michel123456]

The brain is doing the job.

The left brain is connected to the right eye, and the right brain connected the left eye.

The image you see is not in your eye, but in your brain.

 

And the brain can be tricked, look at SIRDS on the web, or http://en.wikipedia.org/wiki/Autostereogram

[Mr Skeptic]

What I'm thinking is their some physics principle that if two different angles concentrate on the same spot, they add up, or has the brain evolved to do this?

 

It is the brain, not any physical principle. If you've ever seen 3D stuff, it works by giving slightly different pictures to each eye, so your brain can construct a 3D merger of the two giving the perception of depth.

[michel123456]

For info i recall an old application:

Making a map from an aerial photograph. A plane (today a satellite) takes a serie of photographs when flying. The overlapping of 2 photographs are used as 2 views of the same thing from 2 different places (because the plane was moving) exactly as it were 2 eyes seeing by binocular view.

Afterwards, a technician takes the 2 overlapping pictures and look at it through a binocular device, reproducing the stereoscopic effect. By sliding slightly the 2 pictures horizontally, the image gets clear at some point, and blur at the other. By this way the experimented technician is able to determine the relative elevation of the observed object.

The 'funny' thing is that any error in elevation in transformed into horizontal error. When a house is very close to a road of well known elevation, the technician usually assumes that the house ground floor is at road level, and puts the house on the map following this assumption. When the house is not at the right level, the position of the house on the map can be wrong for several meters, independently of the accuracy of the photograph.

I hope better methods are used today for mapping.

[scilearner]

Ok I see. Thanks everyone who helped

 

Here is a picture I found that further helped me.

 

[michel123456]

And this is from another forum;

Question

 

How do we see things upright if the image formed on the retina in our eye is an inverted one?

 

Asked by: Shweta Kala

 

Answer

 

It is true that the images formed on your retina are upside-down. It is also true that most people have two eyes, and therefore two retinas. Why, then, don't you see two distinct images? For the same reason that you don't see everything upside-down. One of our most remarkable tools - the brain - is hard at work for us at this task.

 

Processing visual information is a complex task - it takes up a relatively large portion of the brain compared to other senses. This is because your brain performs several tasks to make images 'easier' to see. One, of course, is combining the two images, which is helped by the corpus callosum, the tiny part of your brain which joins the two big hemispheres. The other part is handled in the optic part of your brain itself, and part of its job is to make images right-side-up. It does this because your brain is so USED to seeing things upside-down that it eventually adjusts to it. After all, it's a lot easier to flip the image over than it is to try and coordinate your hands and legs with an upside-down world! As a result, though, it is believed that for the first few days, babies see everything upside-down. This is because they have not become used to vision.

 

Your brain CAN be retrained though. In one psychological study, participants were asked to wear inverting lenses - lenses that invert the image BEFORE they get to your eye, so that when your eye inverts it, it's right-side-up. At first, everything appeared upside-down to the participants. But, after a few days, people began to report that everything appeared right-side-up! As a second part of the study, the people were asked to take the glasses off. Because they were now used to the lenses, their NORMAL vision appeared upside-down!! Within a day, though, their vision returned to normal. The reason you don't see everything upside-down, then, is simply because it's easier to think about right-side-up!

 

Answered by: Michael Brady, Computer Engineering Undergrad., NCSU, Raleigh