The Fog rollout provides controls for simulating participating media like fog, atmospheric dust and so on. The rollout is located under the Environment tab in the right-hand side panel.

Enable fog – Enables aerial perspective fog to be applied in the scene. See the Overview section above.

Fog visibility range – Specifies the distance in km at which the fog has absorbed 90% of the light coming from objects behind it. Lower values make the fog appear denser, while larger values reduce the effect. See the Fog Visibility Range example below.

Fog height – Specifies the height of the fog layer in meters. See the Fog Height example below.

Fog start distance – Specifies the distance from the camera at which the fog starts. See the Fog Start Distance example below.

Fog max opacity – Specifies the maximum opacity of the fog. A value of 1 means the fog is completely opaque, while 0 means the fog is invisible. See the Fog Max Opacity example below.

Fog color – Specifies the color of the fog layer. See the Fog Color example below.

Enable fog 2 – Enables a second aerial perspective fog to be applied in the scene.

Fog visibility range (2) – Specifies the distance in km at which the second fog has absorbed 90% of the light coming from objects behind it. Lower values make the fog appear denser, while larger values reduce the effect.

Fog height (2) – Specifies the height of the second fog layer in meters.

Fog start distance (2) – Specifies the distance from the camera at which the second fog starts.

Fog max opacity (2) – Specifies the maximum opacity of the second fog. A value of 1 means the fog is completely opaque, while 0 means the fog is invisible.

Fog color (2) – Specifies the color of the second fog layer.

Enable scattering fog – Enables scattering volumetric fog. See the Scattering Fog example below.

Fog color – Specifies the color of the fog when it is illuminate by light sources. See the Scattering Fog Color example below.

Fog distance – Specifies the fog density. Larger values make the fog more transparent, while smaller values make it denser. See the Scattering Fog Distance example below.

Fog transparency – Specifies the color of the volumetric shadows and the tint for the objects seen through the fog. Brighter colors make the fog more transparent, while darker colors make it denser at a distance given by the Fog distance parameter.

Fog emission – Specifies the fog emission (self-illumination). You can use this parameter to substitute the ambient illumination inside the fog, instead of using GI.

Fog height – Specifies the height of the fog in meters. See the Scattering Fog Height example below.

Fog start – Specifies the distance from the camera at which the scattering fog starts.

Fog end – Specifies the distance from the camera at which the scattering fog ends.

Fog light boost – Specifies a multiplier for lights that affect the scattering fog. See the Scattering Fog Light Boost example below.

Fog max opacity – Specifies the maximum opacity of the scattering fog while keeping the "light shaft" effect. A value of 1 means the fog is completely opaque, while 0 means the fog is invisible.

Affect secondary rays – Enables or disables the tracing of secondary rays through the volumetric.

Scatter GI – When enabled, the fog also scatters global illumination. Note that this can be quite slow. In many cases, global illumination within the fog can be substituted with a simple emission term. See the Scatter GI example below.

Scatter only infinite direct lights – When enabled, the scattering fog is affected only by directional and sun lights.

Texture mode – Specifies a texture mode to control the scattering fog's density. Available options are Off, Built-in smoke density, and From V-Ray scene.

The following parameters are available for the Built-in Smoke Density mode:

Smoke size – Specifies the size of the smoke "clusters" in meters. See the Smoke Size example below.

Smoke num iterations – Specifies how many times the fractal function is applied. The higher the value, the more detail within the smoke, but the longer the calculation time.

Smoke exponent – Specifies the sharpness of the smoke. Higher values make the smoke sharper and more wispy.

Ground fog – When enabled, adds an additional scattering fog.

Ground fog distance – Specifies the ground fog density. Larger values make the fog more transparent, while smaller values make it denser and more opaque.

Ground fog height – Specifies the height of the ground fog in meters.

Ground fog transition – Specifies the transition falloff height of the ground fog in meters.

Raymarch step size – Specifies the size of one step through the volume. Smaller steps produce more accurate results but are slower to render. In general, dense volumes require smaller step sizes than more transparent volumes. In practice, step sizes that are two to three times smaller than the Fog distance parameter work well.

Raymarch cutoff threshold – Specifies the number of texture samples for each step through the volume. This allows to sample textures more accurately than the volumetric lighting. It is useful in cases where the textures vary much faster than the lighting itself (e.g. for detailed fractal textures).

Raymarch max steps – Specifies the maximum number of steps through the volume.

The following parameters are available for the From V-Ray Scene mode:

Ground fog – When enabled, adds an additional scattering fog.

Ground fog distance – Specifies the ground fog density. Larger values make the fog more transparent, while smaller values make it denser and more opaque.

Ground fog height – Specifies the height of the ground fog in meters.

Ground fog transition – Specifies the transition falloff height of the ground fog in meters.

Raymarch step size – Specifies the size of one step through the volume. Smaller steps produce more accurate results but are slower to render. In general, dense volumes require smaller step sizes than more transparent volumes. In practice, step sizes that are two to three times smaller than the Fog distance parameter work well.

Raymarch cutoff threshold – Specifies the number of texture samples for each step through the volume. This allows to sample textures more accurately than the volumetric lighting. It is useful in cases where the textures vary much faster than the lighting itself (e.g. for detailed fractal textures).

Raymarch max steps – Specifies the maximum number of steps through the volume.

Fog Visibility Range

This examples shows the effect of the Fog visibility range parameter when Simple Fog 1 is enabled.

Fog Height

This examples shows the effect of the Fog height parameter when Simple Fog 1 is enabled.

Fog Start Distance

This examples shows the effect of the Fog start distance parameter when Simple Fog 1 is enabled.

Fog Max Opacity

This examples shows the effect of the Fog max opacity parameter when Simple Fog 1 is enabled.

Scattering Fog

This examples shows the effect of the Scattering Fog.

Scatter GI

This examples shows the effect of the Scatter GI parameter when Scattering Fog is enabled.

Scattering Fog Color

This examples shows the effect of the Fog color parameter when Scattering Fog is enabled.

Scattering Fog Distance

This examples shows the effect of the Fog distance parameter when Scattering Fog is enabled.

Scattering Fog Height

This examples shows the effect of the Fog height parameter when Scattering Fog is enabled.

Scattering Light Boost

This examples shows the effect of the Fog light boost parameter when Scattering Fog is enabled.