Already before the invention of the photography the basics of stereoscopic photography were clarified (Wheatstone 1838).
Also like the acoustic orientation in space the visuel orientation in space bases on the simultaneous perception of two sensual impressions, whose comparison makes it possible to attach positions in space.
To make this impression of space perceptable is done in the case of acoustic perception with simultaneous and different sound from two speakers (stereophonic sound) and in the case of the visual perception with the help of two corresponding different views (stereoscopic photography or film).
Here you can find some historical objects of stereoscopic photography and some stereoviews adapted for the red and green glasses.
