Stereoscopy

Stereoscopy (also called stereoscopics, or stereo imaging) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision. The word stereoscopy derives . Any stereoscopic image is called a stereogram. Originally, stereogram referred to a pair of stereo images which could be viewed using a stereoscope. Most stereoscopic methods present a pair of two-dimensional images to the viewer. The left image is presented to the left eye and the right image is presented to the right eye. When viewed, the human brain perceives the images as a single 3D view, giving the viewer the perception of 3D depth. However, the 3D effect lacks proper focal depth, which gives rise to the Vergence-Accommodation Conflict. Stereoscopy is distinguished from other types of 3D displays that display an image in three full dimensions, allowing the observer to increase information about the 3-dimensional objects being displayed by head and eye movements. Stereoscopy creates the illusion of three-dimensional depth from a pair of two-dimensional images. Human vision, including the perception of depth, is a complex process, which only begins with the acquisition of visual information taken in through the eyes; much processing ensues within the brain, as it strives to make sense of the raw information. One of the functions that occur within the brain as it interprets what the eyes see is assessing the relative distances of objects from the viewer, and the depth dimension of those objects. The cues that the brain uses to gauge relative distances and depth in a perceived scene include: Vergence Accommodation Stereopsis Occlusion - The overlapping of one object by another Subtended visual angle of an object of known size Linear perspective (convergence of parallel edges) Vertical position (objects closer to the horizon in the scene tend to be perceived as farther away) Haze or contrast, saturation, and color, greater distance generally being associated with greater haze, desaturation, and a shift toward blue Change in size of textured pattern detail (All but the first two of the above cues exist in traditional two-dimensional images, such as paintings, photographs, and television.