GISettings

The settings in the <GISettings> group configure the way global illumination is generated for your scene.

NOTE:The settings in this group are only used when rendering scenes with "classic" materials. They are not used at all for physically based rendering.

The following block lists the settings available in this group, with their default values. Descriptions of the settings are below.

<GISettings>
    <enableGI>true</enableGI>
    <primaryIntegrator>finalgather</primaryIntegrator>
    <primaryIntensity>1</primaryIntensity>
    <primarySaturation>1</primarySaturation>
    <secondaryIntegrator>pathtracer</secondaryIntegrator>
    <secondaryIntensity>1</secondaryIntensity>
    <secondarySaturation>1</secondarySaturation>
    <clampMaterials>none</clampMaterials>
    <diffuseBoost>1</diffuseBoost>
    <emissiveScale>1</emissiveScale>
    <specularScale>1</specularScale>
    <enableCaustics>false</enableCaustics>
    <ignoreNonDiffuse>true</ignoreNonDiffuse>
    <prepassMaxSampleRate>0</prepassMaxSampleRate>
    <prepassMinSampleRate>-4</prepassMinSampleRate>
</GISettings>

enableGI

Enables and disables global illumination. Must be set to true in order for any indirect lighting to be calculated using the primary and secondary global illumination integrators, and for any other settings in the <GISettings> group to be taken into account.

primaryIntegrator and secondaryIntegrator

The Global Illumination system allows you to use two separate algorithms to calculate indirect lighting. You can, for instance, calculate multiple levels of light bounces with a fast algorithm like the Path Tracer, and still calculate the final bounce with Final Gather to get a fast high-quality global illumination render.

Accepted values for both settings are:

finalgather: A high-quality GI method that should be used as the primary integrator in most cases. See also the settings described under Final Gather Settings.
pathtracer: A fast algorithm that calculates indirect lighting by tracing a large number of rays from the camera or light map into the scene, and tracing their bounces. See also the settings described under Path Tracer Settings.
none: Use none for the primary integrator when baking advanced passes that perform their own gather: e.g. RNM (when not using radiance cache), or the Lua pass. When these perform their own gather, only the secondary GI will be sampled, making any primary GI useless. Use none for the secondary integrator when you don't need deeper indirect light, or if you have a primary GI that cannot use secondary GI.

You can control the intensity and saturation of the primary and secondary algorithms separately using the <primaryIntensity>, <secondaryIntensity>, <primarySaturation> and <secondarySaturation> settings. See below for details

primaryIntensity and secondaryIntensity

A factor applied to the amount of illumination from the primary or secondary GI integrator. This lets you boost or reduce the amount of indirect light easily.

primarySaturation and secondarySaturation

A factor applied to the amount of color in the primary or secondary GI integrator. This lets you boost or reduce the perceived saturation of the bounced light.

clampMaterials

Determines how materials re clamped for GI purposes. You can use this setting to avoid problems with non-physical materials making your scene extremely bright. This setting affects both the specular and diffuse components of materials.

Accepts the following values:

none: No clamping is performed.
component: Clamps each color component (R, G, B) individually.
intensity: Clamps the intensity of the color to 1. This can be useful to make sure the color of a surface is preserved when clamping. For example, using component clamp on a color like (3, 1, 1) will give the color (1, 1, 1), which means that all color bleeding is lost.

diffuseBoost

This setting can be used to exaggerate light bouncing in dark scenes. Setting it to a value larger than 1 will push the diffuse color of materials towards 1 for GI computations. The typical use case is scenes authored with dark materials; this happens easily when doing only direct lighting since it’s easy to compensate dark materials with strong light sources. Indirect light will be very subtle in these scenes since the bounced light will fade out quickly. Setting a diffuse boost will compensate for this.

Note that values between 0 and 1 will decrease the diffuse setting in a similar way, making light bounce less than normal for each material. Values below 0 are invalid.

The actual computation taking place is a per-component pow(colorComponent, (1.0 / diffuseBoost)).

emissiveScale

This setting can be used to exaggerate or dampen emissive light effects. The emissive components of all materials are multiplied by this factor when they are used by the GI.

specularScale

This setting can be used to exaggerate or dampen specular light effects. The specular colors of all materials are multiplied by this factor when they are used is by the GI.

enableCaustics

Enables and disables the generation of caustics: patterns caused by scattered light that reflects from or refracts through curved surfaces.

ignoreNonDiffuse

When enabled, materials that are non-diffuse will not receive any global illumination.

prepassMinSampleRate and prepassMaxSampleRate

These settings control the sample rate used during the GI precalculation pass. The prepass is progressive, rendering from a low resolution up to a high resolution in multiple passes.

The <prepassMinSampleRate> setting specifies the initial resolution. A negative value means a lower resolution than the original image (in powers of two): e.g. -4 gives the original resolution divided by 16.
The <prepassMaxSampleRate> setting specifies the resolution of the final prepass: e.g. 0 gives the same resolution as the original resolution. The default values are from -4 to 0 inclusive.