Stereopsis
 









That looks like somebody looking at you crosseyed.

Now, look back at him crosseyed.  Cross your eyes far enough that you fuse the image from the right eye with the image from the left eye.

Now, you see three Cyclops, that trio of one-eyed gods of ancient times.  The one in the middle is seen stereoscopically:  His eye is in front, and his pupil is now seen to actually be a retina, located far in the back of his head.

Study of stereopsis, and discovery of stereopsis blindness, was the major work of one-time radar engineer, Bela Julesz of Bell Telephone Laboratories (now Lucent Technologies).  His study of seeing through snow on radar screens led to his development of the random-dot stereogram as a research tool.  He named his field of study, "Cyclopean perception" because it deals with brain activity in the visual cortex, located in the back of the brain where information from the two eyes is combined and processed.  Julesz called this "the cyclopean retina."

Stereopsis is a fascinating phenomenon to study, to play with, to develop into extensions of our perception.  It's also a valuable exemplar for helping us understand and form useful models for other human information processing skills.


some links
Stereopsis is a feature of many pages on this web site.  Many pages have stereoscopic backgrounds.  Many stereoscopic pairs of photo are used on a variety of pages in a variety of ways.  Some of the clues to puzzles are presented stereoscopically. 

Page Backgrounds

Bumpy mattress surface under street map
"The world is three dimensional."
Starry, starry night -- in 3-D
Visual errors
Starry, starry night -- in 3-D
Gateway into Knowledge for Use from Explore Portland!
Starry, starry night -- in 3-D
Secrets of Life -- from above gateway
Starry, starry night -- in 3-D
Navigating Explore PDX and Knowledge for Use  --  in Explore! Portland
Purple-prosed curses
A particularly difficult problem -- on the web as elsewhere
K U P  floating in 3-D like settling sediment
Truth -- Rational or Irrational?
K U P  floating in 3-D like settling sediment
Truth -- Science or Non-science?
K U P  floating in 3-D like settling sediment
Original first page of site
A rotating K N O
The Knowledge for Use Logo
Purple-prosed curses  (background in table)  --  in Explore! Portland
"When neither side can see the viewpoint of the other side..."
Purple-prosed curses  (background graphic in table)  --  in Explore! Portland
Social wellness -- Healthy and unhealthy relationships
Magic  (background graphic in table)  --  in Explore! Portland
Beyond the edges of human comprehension
Stereo Pair Photos
Stereo pair from Rainbow Bridge
Photogrammetry
Posters illustrating visual phenomena 
Da Vinci Days, July, 2000
Southwest Community Center
The stereoscopic model
Denver, Colorado -- in 1948
The stereoscopic model
Roses  --  in Explore! Portland
"What Gold Medal rose is located in all three of our rose gardens?"
The Giant Bird's Eye View  --  in Explore! Portland
Consider extending your perceptions with a little know-how.
Mogen David — with a magical twist.  --  in Explore! Portland
Stereoscopic sculpture
Mogen David — with multiple magic.  --  in Explore! Portland
Multiple stereoscopic sculpture
Trilliums — with multiple mistakes.  --  in Explore! Portland
Some botanical sports — at Tryon Creek State Park Trillium Festival, 2002
Large stereo pairs —   in Explore! Portland
Trillium — Old Maid's Bloomers — Silicon
Duplicate of above, but smaller —   in Explore! Portland
Smaller because eye divergence is used.
Mind-Dancing Into Magic  --  in Explore! Portland
Discovering how to see like a giant: extend your 3-D vision.
Trail construction -- two sets of photos  --  in Explore! Portland
Discovering how to see like a giant: extend your 3-D vision.
Trail construction -- stairs with railing  --  in Explore! Portland
Discovering how to see like a giant: extend your 3-D vision.
Land of impossible streets -- as seen by a giant  --  in Explore! Portland
Discovering how to see like a huge giant (helicopter vision).
Single-photo Stereoscopic Photos
Hardware cloth
Da Vinci Days, July, 2000
Crystal model
Ball-and-stick model: simple cubic lattice  --  in Explore! Portland
Typewriter Stereograms
"Stereopsis is simply one out of many..."
Seeing Science -- Mysteries at the edge...
Quantum leaps are for the birds...
This is probably how you got here.
This isn't really from a typewriter...
But it could have been.
Random Dot Stereograms
The Knowledge for Use Logo
The first random-dot integrated-image stereogram   —   in Explore! Portland
Wallpaper that startles
Da Vinci Days, July, 2000
Phantograms
Amazing stereoscopic images
The clue that reveals The Platinum Plover Egg is stereoscopic

  A Web site with a strong stereoscopic flavor: Donald Simanek, (physicist)