Archive for April 7th, 2011

April 7, 2011

Stereogram

boy with stereoscope by Norman Rockwell

A stereogram [ster-ee-uh-gram] is an optical illusion of depth created from flat, two-dimensional image or images. Originally, the term referred to a pair of stereo images which could be viewed using a stereoscope. Other types of stereograms include anaglyphs and autostereograms. The stereogram was discovered by Victorian scientist, Charles Wheatstone in 1838. He found an explanation of binocular vision which led him to construct a stereoscope based on a combination of prisms and mirrors to allow a person to see 3D images from two 2D pictures. A stereoscope presents 2D images of the same object from slightly different angles to the left eye and the right eye, allowing the brain to reconstruct the original object via binocular disparity.

Oliver Wendell Holmes, Sr. invented an improved form of stereoscope in 1861, which had no mirrors and was inexpensive to produce. These stereoscopes were immensely popular for decades. Salvador Dalí created some impressive stereograms in his exploration in a variety of optical illusions. Stereograms were re-popularized by the creation of autostereograms on computers, wherein a 3D image is hidden in a single 2D image, until the viewer focuses their eyes correctly. The Magic Eye series is a popular example of this. Magic Eye books refer to autostereograms as stereograms, leading most people to believe that the word stereogram is synonymous with autostereogram.

April 7, 2011

Volumetric Display

sony volumetric

actuality systems

A volumetric [vol-yuh-me-trikdisplay is a device that forms a visual representation of an object in three physical dimensions, as opposed to the planar image of traditional screens that simulate depth through a number of different visual effects. One definition offered by pioneers in the field is that volumetric displays create 3-D imagery via the emission, scattering, or relaying of illumination from well-defined regions in (x,y,z) space. Though there is no consensus among researchers in the field, it may be reasonable to admit holographic and highly multiview displays to the volumetric display family if they do a reasonable job of projecting a three-dimensional light field within a volume.

Although first postulated in 1912, and a staple of science fiction, volumetric displays are still under development, and have yet to reach the general population. With a variety of systems proposed and in use in small quantities — mostly in academia and various research labs — volumetric displays remain accessible only to academics, corporations, and the military.

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April 7, 2011

Autostereoscopy

multiview lenticular

spatial view

Autostereoscopy [aw-toh-ster-ee-os-kuh-pee] is any method of adding the perception of 3D depth without the use of special glasses on the part of the viewer. Because headgear is not required, it is also called ‘glasses-free 3D.’

The technology also includes two broad approaches used in some of them to accommodate motion parallax (the perceived change in location of an object seen from two different places) and wider viewing angles: those that use eye-tracking, and those that display multiple views so that the display does not need to sense where the viewers’ eyes are located. Examples of autostereoscopic displays include parallax barrier, lenticular, volumetric, electro-holographic, and light field displays.

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