Stereoscopy

"To see in three dimensions is to receive through each eye the simultaneous impression of two dissimilar images of the same subject." (Euclide)

The three dimension vision by stereoscopy consists in presenting an image taken on the right to the right eye and an image taken on the left to the left eye.

To take a stereoscopic photograph, it is either necessary to use a single camera which would be moved laterally to take the two photographs at exactly the same distance from the subject but at slightly different angles or else a camera with two lenses which fire simultaneously.

To view the stereoscopic image, one can use magnifying glasses to see the two images side by side (stereoscope), use an optical system which projects an image on the retina of each eye while maintaining the head in a fixed position, or use color complementarity to superimpose the two images on the same print or the same screen and use glasses with colored lenses so that each eye sees only the image which is intended to it (process of the three dimension cinema)

In 1838, the Englishman Charles Wheatstone was the first to patent the "stereoscope", a tool provided with two mirrors in which one can observe pictures in three dimensions. In 1839, soon after the creation of the new photographic processes of Daguerre (Daguerreotype) and Talbot (Calotype), Wheatstone used the stereoscope to view photographs in three dimensions. In 1849, another Englishman, David Brewster, invented another process with lenses: Queen Victoria was interested in it and the stereoscopy becomes fashionable. During the Victorian Age, the parlor rooms of amateur photographers and enthousiasts were furnished with increasingly beautiful "stereoscopes", manufactured out of valuable and exotic wood or in mother pearl and ivory.

In 1893 Jules Richard manufactures the Verascope which was the first stereoscopic camera that could be reloaded in full day light.

Stereo photography still exists today: in toys such as the View-Master as well as in some movies which are filmed in 3d (Spykids III being the latest), in some theaters Imax 3d.

NASA uses images collected in 3 dimensions of the solar system or of planets and it is also used in cartography, which make it possible to define the difference in elevations and topography.