The 3D sensation is a reconstruction of space
by our brain, from several informations that it analyses. These
informations are:
- the shift of two images coming from our left
eye and from our right eye.
- the convergence of our two eyes when our sight
is aiming a particular subject.
- the accommodation, which is the focusing of our
eye on a near object.
- the disposition of plans: a tree is hiding a
house, thus it is in the front.
- the lighting which make us to know the hollows
and the bumps.
- our knowledge, on the true size of objects and
things: a dog is smaller than a man, so, if it looks so
important, this is because it is much near, etc...
- Of course, each of these informations has its
own limits.
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Thus, as each case, some datas
will prevail, and other less, or will not. For the near
subjects , there will be the datas of image shift, of convergence,
and accommodation which will be predominant. For the
subjects at intermediate distance, these will be the convergence,
the arrangement, and the lighting. Whereas these will be
mainly the arrangement, the lighting, and our knowledge.
Why that? Because our eyes have
functioning physic limitations, and our visual keenness,
our ability to accommodate, or to converge are only efficient
within some domains.
The keenness allows us to
distinguish two different dots if they are apart of more
than one minute of angle.
The accommodation of our
eyes let us clearly distinguish an object located at some
tenth centimeters when we are young, and at only 2 meters
when we are older. Beyond 3m, the accommodation is not necessary.
The convergence is necessary
to fix an object until a mere 40m, beyond 50m, it is not
necessary.
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