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Advanced Lighting Override

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Concept

Quick Reference

Sets parameters to affect the rendering of a material when it is lit by indirect illumination from global illumination and/or final gather.

Advanced Lighting Override provides controls to change the properties of a material to affect the rendered scene. This control is only available for Realistic and Realistic Metal material types. Global illumination is an indirect illumination technique that allows for effects such as color bleeding. As light hits a colored object in the model, photons bounce to adjacent objects and tint them with the color of the original object. Indirect illumination enhances the realism of a scene by simulating radiosity, or the interreflection of light between objects in a scene. For more information on indirect illumination, global illumination and final gather, see Advanced Rendering.

You can set the following parameters:

• Color bleed scale. Increases or decreases the saturation of reflected color.
• Indirect bump scale. Scales the effect of the base material’s bump mapping in areas lit by indirect light.
• Reflectance scale. Increases or decreases the amount of energy the material reflects. Reflectance is the percentage of diffuse light energy that is reflected from a material.
• Transmittance scale. Increases or decreases the amount of energy the material transmits. Transmittance is the amount of light energy transmitted through a material. A completely opaque material has 0% transmittance.

Materials with a bright diffuse color or high shininess can be highly reflective. This can lead to overexposed or washed-out indirect illumination. In some situations, the controls in the Advanced Lighting Override can improve the appearance of the indirect illumination. Here are some examples of situations where the material's settings can help include color bleeding and large dark areas.

• You might want to reduce Reflectance Scale or Color Bleed Scale when a large area of color (for example, a red carpet in a room with white walls) creates excessive color bleeding. This might be physically accurate, but the eye adjusts for such effects, and the indirect illumination result might look better with less reflectance or less color bleeding.
• You might want to increase Reflectance Scale when the scene includes a large dark area (for example, a black floor). This can lead to a very dark result. You can maintain the floor's color but increase reflectance, giving the material the colors you want while increasing its brightness.

When the material is transparent (like clear glass), the energy transmitted is specular, and light passes directly through the material (subject to refraction). The value of specular transmittance depends on the material's Transparency setting. Usually, when a material has high transmittance, it has low reflectance, and the other way around.