Cross viewing

From Photo-3d

(Thanks to Duane Starcher for this excellent description!)

Pairs of stereo images intended for cross viewing have the image intended for the left eye on the right side, and the right eye on the left side. To view a picture in stereo, display it in its entirety and cross your eyes so that the two halves of the image merge. It is often helpful to over-cross the eyes and let them relax somewhat until the scenes merge into a stereo view. Concentrate your attention on some prominent feature of the scene, preferably in the distance, and get these to merge first. Once full merging takes place you will be able to move your eyes around the scene at will.

Don’t be discouraged if you don’t achieve the stereo effect easily. Some people have more trouble than others, but cross-viewing is a skill than nearly everyone can learn. If you are new to the technique, don’t overdo it. Crossing the eyes tires muscles that are not used to being treated that way. Take frequent breaks until you have built up muscle strength through this unusual exercise. (You will not hurt your eyes in the process.)

(Note: I first learned to parallel free-view images, and had become quite quick at it by the time I first tried to cross-eye view an image. As a result, I had considerable trouble - I found that an aid which helped me was to use a pencil or other object held a short distance in front of the stereo pair. By focusing on this, I was able to get my eyes to cross at approximately the right angle - ed.)