2. UNIT 3 - LIGHT AND ITS SHADOWS
3.1 - THE ILLUSION OF VOLUME
To create the illusion of space, depth and volume on a two
dimensional surface we use different methods to trick the
viewer, like overlapping, transparency, and other applica-
tions of spatial proportion.
But there is another method to create space and volume which is more realistic and effective using
what we called “Light Logic”. Light Logic refers to how light interacts with objects. We need to
understand how this interaction works and apply this knowledge onto our drawing. When a mass is
exposed to light, a solid object will receive more light from one side than another when that side is
closer to the light source. A spherical surface demonstrates this as an even flow tone from light to
dark.
3. UNIT 3 - LIGHT AND ITS SHADOWS
To describe the different tones that go from light to dark we use the term value, which describes all
neutral tones from white, black and all the gray tones in between. If we put all these tones in order
we get what we call value scale.
One of the most used and useful applications of value is creating the illusion of volume and mass on
a two dimensional surface by using the technique called Chiaroscuro.The word Chiaroscuro is a
combination of two Italian words that mean light and dark (chiaro (clear, light) + oscuro (obscure,
dark). It is a technical term used by artists for the use of contrasts of light to achieve a sense of
volume in modelling three-dimensional objects and figures.
4. UNIT 3 - LIGHT AND ITS SHADOWS
3.2 - A LIGHT SOURCE AND SHADOWS
The source of light may be natural as the sun and the
moon or it can be an artificial light. When several light
sources are present the light and dark tones vary and are
less predictable. To simplify the study of light and shadow
we will use only one light source. When a light is projec-
ted onto an object or figure we distinguish three different
parts: a light side and two different shadows whic are a
cast shadow and a form shadow.
LIGHT SIDE:
We find two different zones:
Highlight
The lightest spot or streak is where the light strikes the
subject in exactly the middle of the light side between the
shadow edge and the edge of the object.
Light middle tones
The middle tones on the light side which are lighter than
the values on the dark side. In reverse, the values on the
dark side are darker than the values on the light side.
5. UNIT 3 - LIGHT AND ITS SHADOWS
FORM SHADOW
We find three different zones:
“Shadow edge” or“core shadow”
The edge where the light is blocked from the light source is
the darkest value on the dark side. The core or darkest
value blends into the middle tones from the shadow edge
on round subjects.
Dark middle tone
The variable values blended form the shadow edge on the
dark side. Again, the dark middle tones are darker than any
values on the light side.
Reflected light
If the object being is sitting on a white table, the light from
the table reflects back onto the object and makes the
shadow side lighter. If the object is resting by something
black or dark, the middle values will become a dark reflec-
tion. The concept also holds true when the object is sitting
on a colored surface.
6. UNIT 3 - LIGHT AND ITS SHADOWS
CAST SHADOW
When the source of light is blocked by an object it casts a shadow. The length and shape of the cast
shadow depends on the placement of the light source. Long shadows are cast from a side light
source (as from the sun in late afternoon or early evening), and short cast shadows are cast from
over head (as from a noonday sun). The shape a shadow casts depends on the shape of the object
casting it and how close source is to the object.
7. UNIT 3 - LIGHT AND ITS SHADOWS
The vocabulary used to describe cast shadows in art come from shadow descriptions in astronomy.
The umbra, penumbra and antumbra are the three distinct names given to the description of sha-
dows cast by heavenly bodies.
The umbra is the darkest part of a shadow considered the absence of light. The penumbra is a ligh-
ter outer shadow where the object is only partially obscuring the light. The antumbra seems to
extend out from the penumbra in a lighter and less distinct way.
