A stereogram courtesy of the Boston Public Library: http://flic.kr/p/4zNi8E

The New York Public Library recently introduced one of the niftiest tools I’ve seen on the web in a while. It allows you to take “stereograms“, those side-by-side images that look almost exactly the same and when viewed together create a sense of depth, and turn them into animated GIFs.

The really cool part about this is that if you are careful in how you crop the images, you really can create a sense of depth. You would never expect it in looking at the two static images, but the motion of the animation and the slight differences between the two images really can create the illusion of a 3D image. This one I created of a fountain gives a particularly good sense of the illusion:
I suspect that how it works is motion parallax – one of the actual techniques our visual system uses in depth perception.  The visual system compares differences in distance of an object from each eye, and how those distances change with motion to determine the depth of the object. People who lack binocular vision (the ability to combine information from each eye to create depth perception) can actually gauge depth by moving their heads back and forth to create motion parallax (Stereo Sue is a notable example of this).

The tool can also be used to create other interesting effects. For example, by off-setting the allignment of this stereograph I made it appear to be a film reel slightly out of sync:

This final one I like just because it has interesting aging effects – damage to the images that creates a film grain of sorts. One could also wonder about what the white shadow is… maybe there’s a story in there…

I thought the Stereogranimator was such a cool tool that I decided to submit it as a DS106 Animated GIF assignment (now available here). Hope you enjoy it.