User Manual

Table Of Contents
Material Components
All the standard illumination models share certain characteristics that must be understood.
Diuse
The Diffuse parameters of a material control the appearance of an object where light is
absorbed or scattered. This diffuse color and texture are the base appearance of an object,
before taking into account reflections. The opacity of an object is generally set in the diffuse
component of the material.
Alpha
The Alpha parameter defines how much the object is transparent to diffuse light. It does not
affect specular levels or color. However, if the value of alpha, either from the slider or a Material
input from the diffuse color, is very close to or at zero, those pixels, including the specular
highlights, will be skipped and disappear.
Opacity
The Opacity parameter fades out the entire material, including the specular highlights. This
value cannot be mapped; it is applied to the entire material.
Specular
The Specular parameters of a material control the highlight of an object where the light is
reflected to the current viewpoint. This causes a highlight that is added to the diffuse
component. The more specular a material is, the glossier it appears. Surfaces like plastics and
glass tend to have white specular highlights, whereas metallic surfaces like gold have specular
highlights that tend to inherit their color from the material color.
Specularity is made up of color, intensity, and exponent. The specular color determines the
color of light that reflects from a shiny surface. Specular intensity is how bright the
highlight will be.
Three spheres, left to right: diffuse only, specular only, and combined.
The specular exponent controls the falloff of the specular highlight. The larger the value, the
sharper the falloff and the smaller the specular component will be.
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