Cross-view stereographic viewing, otherwise known as “X3D”, is the easiest HD way to view large-format stereo pairs without glasses.
Quick-Start: Simply view the tutorial video in the link below, or…
View the image pair at a comfortable distance
Stare past the image pair, gently crossing your eyes until you perceive three images
The center image is in 3D
Relax your eyes into it.
The window opens into a stereographic 3D world!
Absent real problems with your vision, any person can learn to do this simple technique in a matter of a minute or two.
Properly done, there is no eye-strain involved.
You will find a distance where the X3D stereo pair can be viewed very comfortably. This distance is usually further from the screen rather than closer.
If you are uncomfortable, simply back off a bit and try again until you find your “sweet spot” for viewing in this manner.
Like riding a bicycle, once you learn the technique of X3D, you will never forget it!
The Real Jimmy Roberts1 has a great video on learning X3D: