The Indigo environment settings can be set from the normal 3ds Max environment settings, allowing a choice of physically-based Sun/sky or environment map illumination in your scene.

For example, to create a Sun/sky environment, open the Environment Settings dialog (keyboard shortcut: 8) and select the Indigo SunSky option from the Indigo Renderer Maps list:

The Indigo Sun/sky and environment map settings are described in the following sections.

Physically-based Sun/sky

Indigo offers two Sun/sky models: either the classical Preetham Shirley Smits model, or the more accurate spectrally simulated model.

• Sky model - Selects the sun and sky model to use; the "classic" model is a standard physically-based sun and sky model, and the captured simulation is the directly simulated sun and sky introduced in Indigo 3.2.
• Sun node - Sets the light source which will act as the sun. This must be specified in order for the sun and sky model to work.
• Sun layer - The light layer index in which the direct sunlight contribution is stored.
• Sky layer - The light layer index in which the skylight contribution is stored.
• Turbidity - A higher turbidity corresponds to more overcast skies. Currently only affects the original sky model.

Image environment map

In this mode, an Indigo Texture (potentially in HDR) can be used as a background map to illuminate the scene. Usually latitude / longitude maps are saved in the compact .EXR format.

• Color - A constant background colour in the given emission units.
• Image - Allows you to specify an Indigo Texture map as an image source. For more information on setting up HDR environment maps, please see the subsection on using image environment maps.
• Intensity - A linear brightness scale factor.
• Exposure - An exponential brightness scale factor.
• Base emission - Allows you to specify a given spectrum map as the basic illumination component, e.g. 6500K blackbody for "white". The Image and Color scale with this base spectral colour.