The Fog node is an atmospheric effect that allows the simulation of participating media like fog, atmospheric dust and so. Volumetric properties can be determined by 3d texture maps. The atmospheric effect can also be confined with geometry objects.
Gizmo - allows you to connect a Fog Gizmo so that the effect is confined within a specified gizmo
Color - defines the color of the fog when it is illuminate by light sources. You can also use a texture map to drive the fog color.
Emission - controls the fog emission (self-illumination). You can use this parameter to substitute the ambient illumination inside the fog, instead of using GI.
Emission Mult:- a multiplier for the Emission parameter
Density - a multiplier for the fog Distance parameter that allows a texture to be used for the density of the fog
Lights - allows you to specify which lights are going to affect the fog
Use Height - when enabled allows you to limit the fog height
Height - specifies an upper limit for the fog
Subdivs - this parameter determines the number of points inside the fog at which volumetric lighting is evaluated. Smaller values for this parameter render faster, but may produce noise in the image. Higher values render longer, but with less noise.
Distance - controls the fog density. Larger values make the fog more transparent, while smaller values make it more dense. You can also control the density with a texture map.
Simplify GI - When this option is checked V-Ray will use a simplified method for calculating the GI when rendering parts of the fog that are textured or are being faded out.
Scatter GI - when on, the fog will also scatter 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. When this option is on, the currently selected global illumination algorithm in the V-Ray settings will be used to accelerate GI inside the volume.
Scatter bounces - when Scatter GI is enabled, this controls the number of GI bounces that will be calculated inside the fog.
Light Mode - this option allows you to specify which lights will be considered when rendering the environment fog. It is used when you have certain lights affecting just specific objects in the scene while another group of lights is affecting the environment fog.
- No lights - the lights in the scene will not affect the environment fog.
- Per-Gizmo (default) - the lights attached to the environment fog set will be ignored. Only the lights affecting the shape where the fog resides, will be used.
- Override - only the lights affecting the environment fog set will be considered.
- Intersect - only lights that are affecting both the shape and the environment fog set will be considered.
- Add - both lights that are affecting the shape and the environment fog set will be considered.