International Stereoscopic Union















 

A Glossary of Stereoscopic Terms

cardboarding (coll.)

A condition where objects appear as if cut out of cardboard and lack individual solidity. Usually the result of inadequate depth resolution arising from, for example, a mismatch between the focal length of the taking lens, the stereo base and/or the focal length of the viewing system.

Cazes stereoscope

A development of the Wheatstone stereoscope by L. Cazes, dating from 1895. It incorporates an extra pair of angled mirrors to view large images of the type used in aerial surveying.

chromatic stereoscopy (or chromostereopsis) (adv.)

An impression of depth which results from viewing a spectrum of coloured images through a light-bending device such as a prism, a pinhole or an embossed 'holographic' filter, caused by variations in the amount of bending according to the wavelength of the light from differing colours (chromatic dispersion). If such a device is placed in front of each eye, but arranged to shift planar images or displays of differing colours laterally in opposite directions, a 3-D effect will be seen. The effect may also be achieved by the lenses of the viewer's eyes themselves when viewing a planar image with strong and differing colours.

chrono-stereoscopy (adv.)

A stereoscopic effect obtained when in time-lapse photography there has been a change in the subject.

Clemetson attachment

Device (named after the inventor) like a rectangular lens hood mounted on a twin-lens stereo attachment used with a mono camera to prevent light spilling into the 'wrong' areas, thus performing a similar function to the internal septum.

Colardeau progression

The advancement of film in a (4- or 5-perforation) stereo camera by a constant two frames, resulting in stereo pairs separated by two unrelated frames. This progression sequence was designed by L.J.E. Colardeau for use with the first 35mm stereo camera, the Homeos, in 1914, and adopted for use with the first mass-produced stereo camera in the 1950s, the Stereo Realist.
The advantage of this progression is that the film travels the same distance each time it is advanced, allowing a simpler and probably more reliable film advance mechanism; it also achieves greater film economy.. The disadvantage is that the individual frame width is limited to one-third of the distance between the centres of the left and right images, which in practice (with a 71.25 mm aperture separation) restricts it to the 5-perforation (23mm) image size.

confocal stereoscopy (adv.)

Focussing the two camera lenses on different planes of the subject matter in order to increase the depth of field perceived in viewing the resulting stereogram.

convergence

The meeting of lines of sight through the eyes, or light rays through the optical system, at a common point closer than infinity.

corresponding points (on a stereogram)

See homologues.

cross-eyed viewing

See free-viewing.

Cyclopean image

The single (three-dimensional) mental image obtained by the brain's fusion of the individual view from each eye (from Cyclops, the legendary giant with a single eye centred in his forehead). See also stereopsis.

 


   

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