When things are drawn or printed on a piece of paper, unless they are one of those specially printed holographic cards, you'd most likely see a 2-dimensional image that uses shading, shadows, and highlights to create foreshadowing or depth of field. However, if you want to produce an image with a simulated 3D image that can trick the eyes, then you'll need a camera with 3D photo maker features.
Stereoscopic Vision and Stereoscopic Cameras
Basically, a 3D images look different than those in 2D mainly because of how they are taken and printed. While 2D images look flat when printed, 3D images look as if certain things are truly closer to you while others are at a distance. For example, in a 3D image, a hand raised towards the viewer would look as if it's actually sticking out of the borders of the picture.
Stereoscopic Vision is a principle which explains why the eyes are able to see depth or various distances. Since humans are born with two eyes that are slightly separated from each other, the two would see similar images but with slight differences in the angles. The brain is able to meld these images together and create an image that depicts depth.
For 3D images to be made, stereoscopic cameras act similarly to the eyes. Some cameras have built-in 3D effects in them that simulate depth, while some have two lenses installed that take two photos at the same time. These two photos look as if one was taken with the right eye while the other one was taken with the left.
Viewing 3D Images
There are plenty of ways to view 3D images—some images are superimposed onto each other with red and blue hints of colors that can only be viewed with 3D glasses. Others are projected onto a specialized screen that either utilize glasses or not. One of the most popular ways is by using a View-master, an inexpensive 3D photo viewer that you can have specially made as a giveaway, gift, or for personal use.
3D images have been in use since the 1890's, and have continued to amuse people of all sorts. With tricks that play with the eyes, 3D images are truly baffling prints. To know more about 3D imaging, you can visit wisegeek.com/what-is-3d-photography.htm and digital-photography-tips.net/stereoscopic.html.
Playful Tricks Baffle the Eye: 3D Photo Makers and View Mast