Some Key Terms and phrases

This post contains a list of stereoscopic 3D related terms and phrases. Most of these are standard industry terms. It serves as a kind of topic specific glossary/dictionary. Words have been added to this based on my current knowledge - i.e. if I didn't know what it meant I made a note of it and found out. There are also a few core stereoscopic terms that I already knew about that are on this list, but I figured the information may be useful for others who come across this list. (I'll also be regularly updating this list throughout my research project, and make a separate post linking here each time I update it.)

Interocular

The interocular separation (or interpupillary distance) refers to the distance between the centers of the human eyes.  For a male adult this distance is typically accepted to be an average of 65mm (roughly 2.5 inches).

Interaxial

Interaxial separation is the distance between the centers of two camera lenses. The human interocular separation is an important constant stereographers use to make calculations for interaxial separation.

Interaxial separation is often incorrectly referred to as “Interocular” and vise-versa. Interaxial separation has come to be known as “i.o.” even though it is the incorrect term.

Convergence

How cross-eyed your eyes are, and how angled the cameras should be to mimic this.

JPS

A stereographic image format based on JPEG. It stands for JPEG Stereoscopic.

Negative Parallax (before the window)

An object appears as if it is close to you; between you and the window.

Zero Parallax

An object is situated on ‘the window’ or ‘screen plane’.

Positive Parallax (behind the window)

An object appears as if it is far away from you; behind the window.

Window Violation

A window violation occurs when an object appears to be before the window, but is touching the edge of the screen. The brain is unable to understand this parallax as it is suggesting the object is before the screen, but at the same time it is obstructed by the screen edge - this will often cause great viewer discomfort.

Stereo-base

See Interaxial
Disparity

Vertical, rotational, zoom, keystone or temporal differences between the left and right eye images. A stereographer never wants disparity, as this can break the 3D effect and cause muscular pain in the viewer’s eyes or even nausea.

Genlock

A device for maintaining synchronization between two different video signals, or between a video signal and a computer or audio signal, enabling video images and computer graphics to be mixed.