Stereoscopic Imaging

How Do 3d Glasses Work

A stereoscopic motion or still picture in which the right component of a composite image usually red in color is superposed on the left component in a contrasting color to produce a three-dimensional effect when viewed through correspondingly colored filters in the form of spectacles.

The modes of 3D presentation you are most familiar with are the paper glasses with red and blue lenses. The technology behind 3D, or stereoscopic, movies is actually pretty simple. They simply recreate the way humans see normally.

Since your eyes are about two inches apart, they see the same picture from slightly different angles. Your brain then correlates these two images in order to gauge distance. This is called binocular vision - ViewMasters and binoculars mimic this process by presenting each eye with a slightly different image.

Wiggle stereoscopy

This method, possibly the most simple sterogram viewing technique, is to simply alternate between the left and right images of a stereogram. In a web browser, this can easily be accomplished with an animated .gif image  or a flash applet  or a specialized java applet.

Pulfrich effect

The Pulfrich effect is a consequence of the fact that at low light levels the eye-brain visual response is slower. The ultimate effect of this is the illusion of depth. A single screen direction must be maintained, or the effect is seen in pseudo-stereo, only very limited "real-world" practical use with this method.

Introduction

 Stereoscopy, stereoscopic imaging or 3-D (three-dimensional) imaging is any technique capable of recording three-dimensional visual information or creating the illusion of depth in an image. The illusion of depth in a photograph, movie, or other two-dimensional image is created by presenting a slightly different image to each eye. Many 3D displays use this method to convey images. It was first invented by Sir Charles Wheatstone in 1838. Stereoscopy is used in photogrammetry and also for entertainment through the production of stereograms.

Transparency viewers

In the 1940s, a modified and miniaturized variation of this technology was introduced as the View-Master. Pairs of stereo views are printed on translucent film which is then mounted around the edge of a cardboard disk, images of each pair being diametrically opposite. A lever is used to move the disk so as to present the next image pair. A series of seven views can thus be seen on each card when it was inserted into the View-Master viewer. These viewers were available in many forms both non-lighted and self-lighted and may still be found today. One type of material presented is children's fairy tale story scenes or brief stories using popular cartoon characters. These use photographs of three dimensional model sets and characters. Another type of material is a series of scenic views associated with some tourist destination, typically sold at gift shops located at the attraction.

LCD shutter glasses

Glasses containing liquid crystal that will let light through in synchronization with the images on the computer display, using the concept of alternate-frame sequencing. See also Time-division multiplexing.

Base line selection

There is a specific optimal distance for viewing of natural scenes (not stereograms), which has been estimated by some to have the closest object at a distance of about 30 times the distance between the eyes. An object at this distance will appear on the picture plane, the apparent surface of the image. Objects closer than this will appear in front of the picture plane, or popping out of the image. All objects at greater distances appear behind the picture plane. This interpupilar or interocular distance will vary between individuals.

Conclusion

Digital cameras are the best for taking stereograms, they are cheap, and can store a lot. Stereograms are not novelties, stereophotography is an art that is true, and more precise to how people see things than 2D photography. It's just an art that lacks a really good, cheap method of presentation: LCD shutter glasses, anaglyphs, lenticular sheets, polarized light, random-dot stereograms, view-masters, direct image overlap by puting eyes in parallel or cross-eyed.