Stare intently at the picture TeaPot. Can you see the hidden image?
Though rarely able to decipher them, I have always been fascinated by stereograms, which involve 3D-images hidden within another picture. In order to "see" the hidden 3-D images, the viewer is asked to stare at the picture until the image starts to take shape. And, I have spent hours staring at images (often to no avail)...which led to some personal intrigue as to the underlying geometry. For example, a sterogram is nothing more than an optical illusion of depth created from flat, two-dimensional images.
Several web sites now exist that not only expose us to a variety of stereogram images, but also help us "see" the hidden images. Some web sites even help you construct your own stereograms. This list is not exhaustive, but it should satisfy your visual urges:
Hope you and your students have fun!
- Thinkquest is a good place to start, as it provides helpful visual hints on viewing stereograms...plus it discusses the underlying geometry (great for a high school project) and provides Java sourcecode (free download) for generating your own stereograms.
- EyeTricks provides many interesting stereograms to test your viewing skills, some hints on viewing stereograms, and an on-line stereogram production program.
- Urry Software Labs is a "giving site", as it gives its stereogram programs away as shareware. The software is powerful, generating 3D images. 3D masks, and 3D movies...plus information on the unerlying theory.
li>Color Stereo takes an unusual "artsy" approach, including things such as roll-over stereograms, minimalist stereograms, arteograms, and valentine stereograms...plus something called the Anaglyph Gallery which requires special 3D glasses. Unusual!
- Vern's SIRDS Gallery offers a ton of SIRDS (Single-Image Random-Dot Stereograms), plus even more links to other web sites that have vast collects of sterograms for viewing (i.e. visual puzzlement).
- A Wikipedia entry adds more background information, a historical perspective, and some "real-world" uses for stereograms.
- Stereograms.net offers a sequenced tutorial to guide the viewer, plus it includes animated stereograms and ASCII stereograms.
- Magic Eye, the producer of book colelctions of stereograms, offers a new stereogram every week and other "3D-fun.".