Stereoscopy

Stereoscopy, which comes from the Greek for “solid look”, is a general term for any technique that can recreate three-dimensional visual information or create the illusion of depth in an image. The general procedure involves creating two two-dimensional offset images presented separately to the right and left eyes, which are then combined in the brain to produce the illusion of three-dimensional depth. Three strategies are employed to achieve the desired effect, two of which involve eyeglasses to either combine or filter offset images, and the third using the lightsource to split the images.

With the exception of stereopsis and eyeball focus, three-dimensional images created through stereoscopy use the same visual cues as traditional two-dimensional images. Stereoscopy enhances the illusion of depth though the illusion is incomplete because stereoscopy fails to satisfy the requirement of eyeball focus. Modern three-dimensional images employ this method that was created in 1838 by Sir Charles Wheatstone. Modern images are generally scanned with a special scanner and then arranged by aligning the left and right pixels via computer. The field of Computer Vision tries to resolve the issue of correspondence by working to create meaningful depth information between the two images used to make the stereoscopic image.

From an anatomical standpoint, there are three requirements that develop during early childhood that enable one to view stereoscopic images: Simultaneous Perception, Binocular “Single” Vision (which is also known as “fusion”), and Stereopsis. Some who have strabismus are unable to develop stereopsis, though orthopics treatments can improve ocular vision. Under certain circumstances where a pair of images is presented, no additional optical device or equipment is required.