Standard Material

Standard Color Components

A surface of a "single" color usually reflects many colors. Standard materials typically use a four-color model to simulate this. (This can vary, depending on which shader you use.) The four colors are known as the material’s color components.

• Ambient color appears where the surface is lit by ambient light alone, where the surface is in shadow.
• Diffuse color appears where light falls directly on the surface, where the surface is in “good” lighting.

  This component is called "diffuse" because light striking it is reflected in various directions. Highlights, on the other hand, are reflections of light sources.

• Specular color appears in highlights. Shiny surfaces usually have specular highlights, where the viewing angle is equal to the angle of incidence.

  A surface can also have glancing highlights, where the angle of incidence is high, relative to the observer or camera (that is, the light ray is nearly parallel to the surface). Glancing highlights are characteristic of metallic surfaces.

  Note: Some shaders generate the specular color procedurally, rather than letting you choose it.

  Some surfaces are completely reflective, or nearly so. These reflect their environment as well as the light sources that illuminate them. To model such surfaces, you need to assign a Reflection map or use ray tracing.

• Filter color is the color transmitted by light shining through the object.

  The Filter color component isn't visible unless the material's Opacity is less than 100 percent.

  Note: The Raytrace material uses a different, six-color model to simulate surfaces. Several components are similar to those in the Standard Material, but they behave differently in Raytrace.

The three color components blend at the edges of their regions. Between ambient and diffuse, the blending is calculated by the shader. Between diffuse and specular, you set the amount of blending by using the Standard material's highlight controls.

When we describe an object's color in conversation, usually we mean its diffuse color. The choice of an ambient color depends on the kind of lighting. For moderate indoor lighting, it can be a darker shade of the diffuse color, but for bright indoor lighting and for daylight, it should be the complement of the primary (key) light source. The specular color should be either the same color as the key light source, or a high-value, low-saturation version of the diffuse color.

For more tips on choosing color components, see Choosing Colors for Realism.

Other Standard Material Components

A standard material's specular color appears in highlights. You can control the size and shape of the highlight. A polished surface has a small and strong highlight. A matte surface has a large, weak highlight, or no highlight at all.

Standard materials also have controls for making the object appear transparent, and for making it self-illuminating so that it appears to glow.

Along with the material's color components, components also refers to the parameters that control highlights, transparency, self-illumination, and so on.