How Do We See Stereo?
For viewing stereo we need both of our eyes. Our brain finally combines the simultaneous images of our eyes to a 3d-impression.
The reason for being able to view stereo is the fact that the two eyes have a different position, their distance between is the stereo base of the eyes. So, the eyes have a different point of view. When focusing to the same point, the lines of sight of left and right image are different, they intersect at the point of interest in an intersecting angle, also called parallax. Nearer points have a bigger parallax than farer ones. This parallax gives us the experience of 3d-viewing.
What Does This Mean For Stereoscopy?
For creating stereograms (stereopair), we need to adopt our eyes capabilities for stereo viewing.
- For first, we need to emulate the eyes view with the stereo capturing tool (camara arrangement, stereocamera …). After capturing you have two images, one for the left eye, the other for the right eye, together, they build a stereogram.
- For viewing the stereogram, we have to present the stereogram (left and right images) in a way that our eyes can see each corresponding image individually. Our brain then combines the images like a normal 3d view.
For capturing stereograms, we emulate our eyes, our viewing. Our eyes build a mainly horizontal base and our eyes look parallel and vertical to tha base (generally when looking far). This consequently is the main principle for taking stereograms.
Another aspect is taking moving scenery synchronously.
Representing and Viewing Stereograms
For reaching the 3d-experience of the stereogram, you need to see each of the images only with the corresponding eye: the left captured image with the left eye, the right captured image with the right eye.
There exist various methods to present stereograms – analog and dgital ones as well as methods with separate images or with overlapped/combinded presentations. Some are giving true colours, others influence or reduce the captured colours. Most methods need utilities for stereo viewing.
Not all will be mentioned here, but for viewing Mindscapers Stereo Gallery, especially the following methods are mentioned:
- Anaglyphs (e.g. red-cyan, red-green, yellow-blue) need Anaglyph stereo glasses – overlapped images, for printing or on screen
red/cyan paper anaglyph glasses
- side-by-side viewing, various implementations for (small) prints or digital; some may be viewed without utilities, but most need various tools (e.g. stereoscopes…)
- Active or passive stereo screens (need corresponding 3d-glasses)
- Dia Show projection with polarized glasses
- wiggling: a digital animation of the stereogram for viewing without stereo utilities
- Virtual Reality (VR) equipment
last update: 04.06.2017