User Manual

Left to right: white, complimentary, and matching specular colors.
Transmittance
When using the software renderer, the Transmittance parameters control how light passes
through a semi-transparent material. For example, a solid blue pitcher will cast a black shadow,
but one made of translucent blue plastic would cast a much lower density blue shadow. The
transmittance parameters are essential to creating the appearance of stained glass.
TIP: You can adjust the opacity and transmittance of a material separately. It is possible
to have a surface that is fully opaque yet transmits 100% of the light arriving upon it, so
in a sense it is actually a luminous/emissive surface.
Transmissive surfaces can be further limited using the Alpha and Color Detail control.
Attenuation
The transmittance color determines how much color is passed through the object. For an object
to have fully transmissive shadows, the transmittance color must be set to to RGB = (1, 1, 1), which
means 100% of green, blue, and red light passes through the object. Setting this color to RGB =
(1, 0, 0) means that the material will transmit 100% of the red arriving at the surface but none of
the green or blue light.
Chapter – 76 3D Compositing Basics 1564