# Thread: how the brain asseses distance

1. how we know by our eyes that one object closer then the other?

2.

3. Well, since your eyes' field of vision overlaps...

http://en.wikipedia.org/wiki/Stereoscopic_vision

Look at T-Rex. Since his eyes overlapped, he had depth perception - important feature in a hunting animal. This is why alot of Paleontologists think it was an active hunter.

No doubt we would make some nice Human McNuggets.

4. i am a student of electrical engineering
and i want to make this property artificially

is there any more descriptive articles
algorithms
??

5. Originally Posted by hybrid
i am a student of electrical engineering
and i want to make this property artificially

is there any more descriptive articles
algorithms
??
http://en.wikipedia.org/wiki/Computer_stereo_vision

It's a hard thing to Google. You get all kinds of useless links to things that have nothing to do with machines gaining depth perception, unless you use the right search term.

When a camera captures an image, you automatically know the relative angle between the direction the camera is facing and every object in the picture. Each pixel can only originate from exactly one angle. If you have two cameras, set apart by a small distance, then the two angles in the two photographs, taken together with the distance between the cameras, form a triangle, and you can use trigonometry to determine the distance.

The trick is getting the computer to be able to tell which pairs of pixels are coming from the same object. If you see two pictures of a stop sign, taken from two different angles, you can intuitively tell which part of each picture is the "S" from the word "Stop". But, how does a computer tell that? How does it tell the difference between a white "S", and a random patch of white?

6. There are many ways to tell distance. A single image can tell relative distance by one object obscuring another. This is often used in optical illusions to create a sense of confusion in an image. Another issue is motion parallax. In this method the eye moves causing objects to move across the field of view. Closer objects appear to move further than more distant objects.

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