Stereoscopic imaging is a way of creating an illusion of depth in an image using two different pictures of an object. There are many forms of stereoscopic images, from the blue and red 3D photos that you used as a kid to read 3D comics, to the special glasses used at 3D movies at theaters.
The use of stereoscopic imaging dates back to 1840. During that time, you used special glasses that allowed people to see the 3D effect of stereoscopic images easily. While many people tend to use special glasses, it is possible with a bit of patience to see the illusion without anything but your own eyes and patience. Even that figure up top! Read the rest of the article to learn how, as well as see many more stereoscopic images of Japan.
I prefer Vision 3D‘s approach, even tho they say “for advanced free-viewers — only Olympians of free-viewing need apply.”
Another method for 3D viewing is called cross-viewing or the cross-eyed method. You aim your eyes so that the lines of sight of your eyes cross in front of the image. When you cross-view, the muscles inside your eye
that control the focusing lens contract strongly and shorten.
However, you may want to read more on how to view 3D Stereoscopic images as there is also a parallel method which I can’t seem to master. Here are some more 3D stereoscopic pictures from Japan. For better viewing, click for the larger version.