3D Television Technology

Parallax

Did you know that the way astronomers tell the how far away a star is works very similar to how you determine how far away an object is? They both use the principle of parallax. Parallax is the concept that an object will look to be in two different positions when viewed from two different lines of sight. Take a look at the diagram below. When the object is viewed from Viewpoint A, it will look like there is a blue background behind the object. When viewed from viewpoint B, there will be a red background behind it.

From different viewpoints, the object appears to have a different background due to parallax.[1]

As the Earth orbits around the Sun, astronomers will look at a some star. Depending on where in the Earth's orbit they are viewing the star from, the stars behind the star they are looking at will appear to be different. If you look in the diagram below, when viewing the near star, it will appear to have different stars behind it dependent on where the star is viewed from. Your eyes work in a similar way. Since your left and right eyes are at slightly different places, they experience parallax as well. This is what is known as stereopsis.

The Earth is shown travelling in its orbit. When an observer on the Earth looks at a nearby star, it will see different background stars behind the near star depending on where in the Earth's orbit the observer is looking from. [2]
Stereopsis &larr Parallax &rarr Stereopsis & Parallax Quiz, Types of 3D Display
[1] Image retrieved from en.wikipedia.org on July 20, 2010. Permission granted under GNU Free Documentation License.
[2] Image retrieved from en.wikipedia.org on July 21, 2010. Image is public domain.
© Copyright 2010, Jeffery Dech, John Donohue, and Ryan Woodman