Toronto. Paintings and regular photos are done in two dimensions. Careful use of shadows (lighting for photos) give a more modelled view of the subject.
Most humans have two eyes 2 to 3 inches apart giving two images of any view at two slightly different angles of view. The human brain fuses these two images to give a three dimensional (stereo) view.
This article in the May 1925 issue of Science and Invention magazine explains stereo and how to take and correctly align stereo photos taken with these inexpensive box cameras. The stereo fad seems to wax and wan. Every half century or so stereo interest peaks once again. c1900 stereo cards are popular collectible items again. Fake stereo cards exist. The same photo is used on both left and right making the result totally flat when viewed correctly.
In the 1950s stereo popularity rose again with special stereo attachments and cameras. The stereo fad seems to fade because, like movies, special care had to be taken and on top of that few people could “free view” stereo so special viewers were needed. Anaglyphs using two different colour allowed both images to be printed on one sheet.
Special books of stereo drawings using repeated symbols could be bought late last century and free viewed by many people but only crude drawings could be viewed. For a short time so called lenticular views could be taken with a four lens camera and special processing of the prints.