Perspective Projection - Transformations and Projections in Computer Graphics - page 129

If you relax, practice this method several times, and do it slowly, you should be
able to slide the two targets and align them perfectly. You may need to tilt your head
slightly left or right to align the targets vertically.
4. When the two targets fuse, move your eyes slowly from your fingertip to the
fused image on the page. Don't forget to keep your eyes crossed during this step.
If this “trick” is successful, apply it to a pair of stereo images such as Figure 3.49.
Experience indicates that most people get used to this way of viewing stereoscopic
images and don't find it tiring or uncomfortable. However, if you feel discomfort or
if your eyes get tired, don't try this method again!

There are other ways to enjoy

stereoscopic images.

Figure 3.49: A Stereo Pair (color version on page 235).

The Parallel View Technique
This technique (also referred to as relaxed viewing) is appropriate for small images
where each image of a stereoscopic pair fits between the eyes. The pair is displayed
with the right-eye image on the right and the left-eye image on the left, as illustrated
here:

LR

left eye right eye
The following steps show how such an image can be viewed stereoscopically without
any tools or instruments. Those who wear glasses may get better results trying these
steps without their glasses.
1. Watch the image pair from close range so that each eye is over one of the images.
This is possible if the images are small enough.
2. Stare straight ahead and try to gaze through the images to infinity. The stereo
images will look blurred.
3. Slowly pull your head away from the page while maintaining the same gaze. The
two images will turn into four images. Continue to move away while gazing to infinity.