Re: how do i make a 2d image appear 3d

 Thank you for your question. What you describe is one of the most 
fascinating visual experience. It's almost magic, isn't it?

 When we look at an object, our two eyes see slightly different images 
of the object because they look at it from slightly different viewpoints. 
This results in two slightly different retinal images (projections of the 
object on the retinae, which are like screens in the back of the eyes). 
The small differences between these images are then "computed" by 
the brain, and used to determine the depth of the object and its 
three-dimensional shape.

 The exhibit you saw in the science museum was a demonstration of 
this process, which is called "stereopsis". It's discovery is usually 
attributed to Charles Wheatstone (1838). Wheatstone reasoned that 
if he presented to the eyes two slightly different pictures, this would 
create two slightly different retinal images and a three-dimentional 
representation of the presented images would appear! 

 As you by now realize, the images you saw in the science museum 
where not identical. Some components of the images were "shifted" 
relative to one another. Master painter Salvatore Dali understood this 
principle. The two paintings below at first glance appear identical, but 
closer examination reveals that several components of the pictures 
are "shifted". The woman, for example, stands directly on the sun in 
the right picture, but is shifted to the right in the left picture.
 In this arrangement, looking at the right picture with your right eye 
and at the left picture with your left eye will create the vivid impression 
of a woman "coming out" of the picture in 3D! The glasses in the 
science museum were filters that allowed each eye to see only the 
appropriate picture. Wheatstone achieved the same purpose with 
mirrors. With practice, you can do it by simply "diverging" your eyes, 
that is by letting your eyes drift outwards towards the picture they 
should see. To acheive this, only relax your eyes and try to look 
"behind" the pictures. Note that the same effect can be acheived by 
switching the pictures and crossing your eyes!

 It is easy to create your own "stereograms" using for example Adobe 
Photoshop or Illustrator. Just create two identical images, then shift 
some components! 

 I hope this helps. For more information, have a look at any good 
"Perception" textbook, under "stereopsis". They are usually availble in 
all university librairies. 
 
 Good luck and all the best to you! Benoit