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charge of establishing representations of visual information at different scales of the
observed space.
After this brief description of the organisation of the visual system, we will now
focus on the functioning of these channels and present a mathematical model related
to the concept of frequency so as to analyse the functioning of the visual system. In
practice, we will use this analysis to characterise the performances in stereoscopic
vision and to improve this type of vision.
For this purpose, we will study the perception of depth by monocular vision and
by binocular vision after studying the monocular processing of information.
3.2.1 The human visual system
3.2.1.1 The entire visual system
The two eyes, the sensory receptors of the visual system, participate in the observation
of space. The optic nerves from the eyes come together at the optic chiasm where the
left temporal fibres meet the right nasal fibres and vice versa. The fibres of the optic
nerve are then directed towards the lateral geniculate body, except a small part of the
fibres that is directed towards the superior colliculus. One of the supposed roles of the
lateral geniculate body is to separate the neurons receiving the retinal afferents into
different cellular layers. From the lateral geniculate body, the information is sent to
the occipital cortex, also known as striate cortex for its lamellar structure. Figure 3.2
shows the path of visual information from the eye to the visual cortex.
The striate cortex, or the visual cortex or V1, is organised in such a way that a
representation of the incidental information is produced on the retina. As in the lateral
geniculate body, all the regions of the retina are projected here and the contiguity of the
spatial representation is stored in it (DeValois & DeValois, 1988). The organisation
of the striate cortex is retinotopic. The layout is however different - the central retina
is projected with a higher dilation factor than that of the peripheral retina, caused
mainly by the density of the retinal sampling. The representation of the information
in the striate cortex is however a lot more complex than a simple geometric structure.
Retina
Optic nerve
Optic
Chiasm
Lateral geniculate
body
Visual cortex
Figure 3.2 Retinal projections towards the lateral geniculate body, then to the striate cortex
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