Editing 3D display (section)

===Side-by-side images===
[[File:Early bird stereograph2.jpg|thumb|''"The early bird catches the worm"'' stereograph published in 1900 by North-Western View Co. of [[Baraboo, Wisconsin]], digitally restored]]

Traditional stereoscopic photography consists of creating a 3D effect starting from a pair of 2D images, a [[stereoscopy|stereogram]]. The easiest way to enhance [[depth perception]] in the brain is to provide the eyes of the viewer with two different images, representing two [[Perspective (visual)|perspectives]] of the same object, with a minor deviation exactly equal to the perspectives that both eyes naturally receive in [[binocular vision]].

If eyestrain and distortion are to be avoided, each of the two 2D images preferably should be presented to each eye of the viewer so that any object at infinite distance seen by the viewer should be perceived by that eye while it is oriented straight ahead, the viewer's eyes being neither crossed nor diverging. When the picture contains no object at infinite distance, such as a horizon or a cloud, the pictures should be spaced correspondingly closer together.

The side-by-side method is extremely simple to create, but it can be difficult or uncomfortable to view without optical aids.

====Stereoscope and stereographic cards====
{{Main|Stereoscope}}

A stereoscope is a device for viewing stereographic cards, which are cards that contain two separate images that are printed side by side to create the illusion of a three-dimensional image.

====Transparency viewers====
{{Main|Slide viewer#Stereo slide viewer}}
[[File:View-Master Model E.JPG|thumb|A View-Master Model E of the 1950s]]
Pairs of stereo views printed on a transparent base are viewed by transmitted light. One advantage of transparency viewing is the opportunity for a wider, more realistic [[Dynamic range#Photography|dynamic range]] than is practical with prints on an opaque base; another is that a wider [[field of view]] may be presented since the images, being illuminated from the rear, may be placed much closer to the lenses.

The practice of viewing film-based stereoscopic transparencies dates to at least as early as 1931, when [[Tru-Vue]] began to market sets of stereo views on strips of [[35mm format|35 mm film]] that were fed through a hand-held [[Bakelite]] viewer. In 1939, a modified and miniaturized variation of this technology, employing cardboard disks containing seven pairs of small [[Kodachrome]] color film transparencies, was introduced as the [[View-Master]].

====Head-mounted displays====
{{Main|Head-mounted display}}
The user typically wears a helmet or glasses with two small [[LCD]] or [[Organic light-emitting diode|OLED]] displays with magnifying lenses, one for each eye. The technology can be used to show stereo films, images or games. Head-mounted displays may also be coupled with head-tracking devices, allowing the user to "look around" the virtual world by moving their head, eliminating the need for a separate controller.

Owing to rapid advancements in computer graphics and the continuing miniaturization of video and other equipment these devices are beginning to become available at more reasonable cost. Head-mounted or wearable glasses may be used to view a see-through image imposed upon the real world view, creating what is called [[augmented reality]]. This is done by reflecting the video images through partially reflective mirrors. The real world can be seen through the partial mirror.

A recent development in holographic-waveguide or "waveguide-based optics" allows a stereoscopic images to be superimposed on real world without the uses of bulky reflective mirror.<ref>{{cite web|url=http://physicsworld.com/cws/article/news/2014/jul/31/new-holographic-waveguide-augments-reality |title=New holographic waveguide augments reality. |publisher= IOP Physic World |year=2014}}</ref><ref>{{cite web|url=https://www.microsoft.com/en-us/research/project/holographic-near-eye-displays-virtual-augmented-reality/ |title=Holographic Near-Eye Displays for Virtual and Augmented Reality. |publisher= Microsoft Research |year=2017}}</ref>

====Head-mounted projection displays====
Head-mounted projection displays (HMPD) is similar to head-mounted displays but with images projected to and displayed on a [[Retroreflective sheeting|retroreflective screen]], The advantage of this technology over head-mounted display is that the [[Accommodation (eye)|focusing]] and [[vergence]] issues didn't require fixing with corrective eye lenses. For image generation, [[pico projector|pico-projectors]] are used instead of [[LCD]] or [[Organic light-emitting diode|OLED]] screens.<ref>{{cite journal|title=A mobile head-worn projection display. | pmid=19550732 | volume=15 | issue=22 | journal=Opt Express | pages=14530–8 | last1 = Martins | first1 = R | last2 = Shaoulov | first2 = V | last3 = Ha | first3 = Y | last4 = Rolland | first4 = J | doi=10.1364/oe.15.014530| year=2007 | bibcode=2007OExpr..1514530M | url=https://stars.library.ucf.edu/cgi/viewcontent.cgi?article=8407&context=facultybib2000 | doi-access=free }}</ref><ref>{{cite journal|title=Investigation of a 3D head-mounted projection display using retro-reflective screen. | pmid=25089403 | volume=22 | issue=15 | journal=Opt Express | pages=17823–9 | last1 = Héricz | first1 = D | last2 = Sarkadi | first2 = T | last3 = Lucza | first3 = V | last4 = Kovács | first4 = V | last5 = Koppa | first5 = P | doi=10.1364/oe.22.017823| year=2014 | bibcode=2014OExpr..2217823H | doi-access = free }}</ref>