International Stereoscopic Union


A Glossary of Stereoscopic Terms


Term used to describe the result arising when the film plane in a camera or projector is not parallel to the view or screen. The perspective distortion which follows from this produces an outline of, or border to, the picture which is trapezoidal in shape, resembling the keystone of a masonry arch.
In stereo, the term is applied to the taking or projecting of two images where the cameras or projectors are 'toed-in' so that the principal objects coincide when viewed. The proportions of the scene will then have slight differences which produce some mismatching of the outlines or borders of the two images. Gross departures from orthostereoscopic practice (eg, if using telephoto lenses) can produce keystoning in depth; more properly called a frustum effect.


(arch.) Pertaining to a lens. As used by Brewster to describe his lensed stereoscope.

Shaped like a lens. In stereo, used to describe:
(1) A method of producing a depth effect without the use of viewing equipment, using an overlay of semi-cylindrical (or part-cylindrical) lens-type material which exactly matches alternating left and right images on a specially-produced print, thereby enabling each eye to see only one image from any viewing position, as in an autostereogram.
(2) A projection screen with a surface made up of tiny silvered convex surfaces which spread the reflected polarised light to increase the viewing angle.

Lilliputism (coll.)

Jargon term for the miniature model appearance resulting from using a wider-than-normal stereo base in hyperstereography.



International Stereoscopic Union
8008 Zurich

Phone: +41 (44) 508 1024