What is Stereoscopy?
You may have seen these
pictures, often called "
Magic Eye" posters, in
books,
on display in
malls or even on the
internet (http://www.netaxs.com/~mhmyers/rds-ex.html). These are called
Stereograms.
Stereoscopy is the art of creating stereoscopic images that trick your brain into seeing a 3D image in the background of a 2D picture.
How do they work?
To create these, two images of the same scene are placed side by side, one slightly offset from the other. Usually a picture, or pattern is placed over top of this to disguise the images.
When you view these images, your brain receives the two images, one from each eye, and overlays them allowing you to see a 3D picture "pop out" at you.
You can download tools to create stereoscopic images on your PC from: http://www.ucl.ac.uk/~ucapwas/sisgen.html or http://msia02.msi.se/~lindsey/java/demo2/Stereo2.html. These are just two examples, there are many, many more tools available for this.
Hints on viewing them:
Put your face close to the monitor/page and attempt to look through the image, at the wall behind it.
Now slowely, still focusing on that point, move your head back.
This may take several attempts, so be patient.
Once your eyes know how to focus (or unfocus as the case may be), you will be able to quickly adjust them when viewing stereoscopic images in future.
Examples:
The following are examples of stereoscopic pictures using ASCII Art. See if you can see them.
n t t t t t t t t t t t t t t t
f a a a a a a a a a a a a
e r r r r r r r r r r r r r r r
a q q q q q q q q q q q q
a u u u u u u u u u u u u u u u
r i i i i i i i i i i i i
r n n n n n n n n n n n n n n n
f i i i i i i i i i i i i
e o o o o o o o o o o o o o o o
a u u u u u u u u u u u u
a s s s s s s s s s s s s s s s
. . . .
. . . .
+ + + + +
. . . .
* * * *
. . . .
. . . .
+ + + +
* * * *
. . . .
. . . .
. . . .
+ + + + +
. . . .
. . . .
* * * *
. . . . .
. . . .
+ + + + +
. . . .
* * * *
. . . .
* * * *
. . . .
. . . .
+ + + +