Special Considerations for Rendering
For physically correct material definitions, it is important that the Efficiency does not exceed 100%. In the real-world, materials generally range in efficiency from 30% to 70%.
Effects of Material Settings
When the rendering process comes across a material definition, the four components — Diffuse, Specular, and Opacity, and Glow, all have an effect on the outcome.
- Diffuse — the material's Base Color scaled by Diffuse, represents the percent of light (in each color) reflected by each light. This diffuse color determines how bright the material appears when illuminated, and how much light is reflected onto other surfaces.
For materials that are pattern-mapped, Color is first blended with the pattern map, and then Diffuse is applied.
- Specular — the Specular Color, scaled by Specular, represents the percent of light (in each color) that is reflected off a surface as a specular highlight, where you can "see" a reflection of each light source in the surface. When additionally scaled by Reflect, this yields the percent of light (in each color) that is seen in a reflection of an object. This value also represents the amount of light that will be reflected in the mirror direction onto other surfaces, accounting for caustics.
- Opacity — the Specular Color scaled by Opacity, represents the percent of light (in each color) that passes through a surface. Note that this means that a material with a Specular Color of black will never transmit any light, even if Opacity is set at zero. This applies when the material is casting shadows and when objects are seen through the material.
- Glow — the Glow setting is used to create special effects such as neon lights. The value for Glow adds to the overall reflectance of the material and is independent of the amount of incoming light.