The New York Public Library has an archive of over 40,000 historical stereographs, many well over a hundred years old. Stereographs are regular photographs, except in pairs, with the perspective very slightly different. Essentially, stereographs are what you were looking at through your ViewMaster as a kid. And now the NYPL has created a pretty amazing tool they’re calling the Stereogranimator that lets users create animated 3-D GIFs from the photos in the archive.
Moving the image back and forth between the two perspectives tricks the eye into seeing depth–it’s kind of a lo-fi way to get around that problem of both eyes seeing the same thing. (Regular 3-D beams a different image to each eye.) Here’s a recent example:
It’s especially cool that the tool, while easy to use, isn’t really automatic–you still have to play around with it to get the perspective and speed just right. Go check it out!