The following pairs of pictures can be looked at stereoscopically by using the cross-eyed method. When going cross-eyed, each eye receives its own image. A spatial perception is formed in the heads of the spectator from a comparison of the two almost identical photos.
can be learnt and applied easily.
Place your index finger between your face and a pair of pictures on the screen.
Stare at your fingertip.
Change the distance between your finger and your face until three pictures appear in the background.
Concentrate on the middle picture. It will appear in sharp focus and in three dimensions.
Pictures by Hans Knuchel. Published 1984 by Tanner and Staehlin, Zurich (Reise in Land der 3. Dimension) and 1992, -94, -96 by Lars Mueller, Baden (Stereo, See Saw and Flatland).