VISUAL PERCEPTION Part-1


Lets skip the electric and chemical aspects of vision, and lets focus on the sensorial perception itself, on what we actually see.
Visual perception is given by the sensorial perception and our visual experience.

Lets examine the result of the process our eyes and brain follow to give a meaning to what we see.
The majority of our perceptions are incredibly complex as they are immediate and automatic, even when the informations that actually reaches our eyes is scarce.

You will certainly realize yourself that reading this text doesn't require us to comprehend each single letter, decypher, compose the letters in single words, sum it to all the others and add punctuation to understand the meaning of what is written, but, to put it simply, we recognize the meaning throught familiar shapes.

The familiarity with words is given from reading skills acquired in school, and all the rest is given bt the sensorial messages obtained throught the lines that compose the letters.
So visual perception (as all kinds of sensorial perception) is composed by both experience and sensorial perception.
The sum of the two parts is sucha rapid process it is practically subconscious.

In our case, since we are trying to find the right way of describing volume, lets put down some depth percection indicators:

_A series of horizontal lines one above the other that becoming smaller and closer together give a sense of depht. Parallel lines converge with increasing distance such as roads, railway lines ecc
This effect is called
LINEAR PERSPECTIVE.




If you draw pattern of point on a plane in which elements of the pattern appear to recede by consistently becoming smaller, denser, and fainter, you have an illusion of deepht.
This effect is called
TEXTUREAL PERSPECTIVE


When there is overlapping of objects the overlapped object is considered further away
This is called INTERPOSITION.


If there is an elevation difference between 2 identical objects, the higer object is considered further away
This is called ELEVATION .



Shading applied to a form shows volume
Its a LIGHT And SHADE effect.

These indications, used by the artist to indicate depth are called "monocular", because they give the illusion of depth without the aid of binocular three dimensional vision.
Our cerebral/visual apparatus is extremely fascinating.
Our brain decodes the signals from our eyes and subconsciously understands and sometimes even completes shapes and volumes, lines and silhouettes.

Among the depth indicators we mentioned above the ones we are most interested in now are Perspective and Shading.
For now we can say the most frequent kinds of perspective are one point and two point perspective.
As you might know the representaion of volume on a flat surface is mere illusion, a way of tricking the viewer.
Some times a group of lines in the right place might transform a flat shape (Fig 1A) in a three dimensinal one (Fig 1B).
There are different ways to create thins kind of illusion, and perspective is one of them.
Similar results are achieved with axonometry, which is a way of simplifying actual vision and is mostly used in architecture, technical and mechanical drawing.
But the greatest help comes from light, that described for and shows each object for what t is.
In drawing and painting, light is represented through Chiaroscuro, the Shading we were refferring too earlier.
As the adding of lines give a 3d look to a 3d shape, shading gives volume . (Fig 1C)

Translation by Ryan Lovelock