Refraction
is how much a ray of light will
bend when it passes through an object.
This bending generally occurs at
the interface between 2 types of
media. Light behaves in much the
same way as it moves from air, where
it travels very fast, into another
medium like glass or plastic or
water, where it travel more slowly,
hence bending the path of travel.
The
angle of refraction depends on the
angle of incidence and the difference
between the two mediums. When the
incident ray is perpendicular to
the surface, no refraction occurs
and the ray passes straight through
the second medium.
Refraction
is what gives rise to the shimmering
bands of light often seen in the
bottom of shallow pools of water.
Or a magnifying glass its magnifying
properties.
In
RS3D, we call the Refraction Index,
Optical Thickness. When defining
the Refraction index of the default
glass for example, we use the following
formulae:
optical
density = 1 - 1/IOR
For
example:
glass = 1 - 1/1.5 = 1/3 = 0.3333
diamond = 1 - 1/2.4 0 = 0.59
(Use this 0.59 number in the refraction
field in simple mode)
Refraction
will only work if your material
is partially or completely transparent.
(ie
the Transparency channel has a value
higher than solid black)
If
the Refractive Index is set to 1.0,
then light does not bend when it
passes through the object.
Here are some other useful values
for Refractive Index: