Viewing stereoscopic pictures
In principle, viewing stereoscopic pictures is simple: two pictures are
displayed, one from the perspective of your right eye, one from the perspective
of your left eye. If we call these pictures R and L respectively, the trick
is to let your right eye see R, while your left eye sees L. This can be done
in two ways, illustrated below:
- Put the pictures, L and R, next to each other, L left and R right,
and let your left eye see L and your right eye see R by directing your eyes
at a point at far distance, yet focussing on L and R. This is called parallel
or distal viewing. This method has the advantage that it is not too difficult to
learn if the separation between the images is not very large. In practice, the
separation between L and R should not exceed ca. 6 cm. (being the distance
between your eyes), which means the
pictures themselves cannot be wider than that distance, which can be an
annoying limitation.
- Alternatively, put L and R next to each other, L to the right and R
to the left. Then, look at a point at close distance, closer than the pictures
are. This implies your will be looking cross eyed. Then focus at the pictures.
This form of viewing is called cross-eyed, or proximal. Some find it less easy
to learn, but after a bit of practice, this is a very convenient way of
viewing stereo pictures. Moreover, the distance between the pictures, and
therefore their size, does not play a role: even if the pictures have several
meters distance between them, you can still view them cross-eyed.
The figure below illustrates these two ways of viewing.
