This example demonstrates the effect of the fog color. Note how color only changes the way the volume reacts to light, and not the volume transparency. In this example, the fog density is mapped with a checker texture. A Box gizmo is used to confine the fog volume.
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In the following examples, the fog color has been mapped with a texture. World XYZ mapping type was used for the textures.
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A Gradient Ramp texture with Solid interpolation.
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A Noise texture with Turbulence type.
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Emission - controls the fog emission (self-illumination). You can use this parameter to substitute the ambient illumination inside the fog, instead of using GI.
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Example: Fog emission
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This example demonstrates the effect of the Fog emission parameter. The Fog color is gray so as to better show the effect of the emission. Note that since we also have GI enabled, the fog emission causes the volume to illuminate both itself and other objects around it. The fog density is mapped with a Checker texture. A Box gizmo is used to confine the fog volume.
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Fog emission is black (no emission),
Fog color is gray
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Fog emission is dark blue,
Fog color is gray
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Fog emission is dark blue, Fog color is black
(only the fog emission affects the image)
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In the following examples, the Fog emission has been mapped with a texture. The Fog color is gray to better show the light scattering inside the volume, produced by the global illumination. The scene for the last image is available here.
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Fog emission is mapped with a
Gradient Ramp texture.
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Fog emission is mapped with a red Noise
texture with Turbulence type.
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Emission Multiplier - a multiplier for the Emissionparameter
Fog distance - controls the fog density. Larger values make the fog more transparent, while smaller values make it more dense.
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Example: Fog distance
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This example demonstrates the effect of the Fog distance parameter. Note how larger values make the fog more transparent. A Box gizmo is used to confine the fog volume.
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Fog distance is 4.0
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Fog distance is 16.0
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Fog distance is 64.0
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In the following examples, the fog density has been mapped with a texture. World XYZ mapping type was used for the textures.
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No texture
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Checker texture
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Regular Noise texture
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Inverted turbulence Noise texture
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Fog density- a multiplier for the Fog distance parameter that allows a texture to be used for the density of the fog
Fog height - if the fog is not contained within a volume, it is assumed to start from a certain Z-level height and continue downward indefinitely. This parameter determines the starting point along the Z-axis.
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Example: Fog height
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When there are no gizmo nodes connected to VRayEnvironmentFog, the volume occupies space downward from a certain height along the scene Z-axis, determined by the Fog height parameter. The following examples demonstrate this. Note that as the Fog height is increased, the scene becomes darker - this is because the sun is blocked by a larger amount of fog. This can be corrected by increasing the Fog distance parameter, and thus making the fog more transparent. Note also the sudden decrease of brightness when the camera is included inside the fog volume. For more info on gizmo nodes, see the Example below.
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Fog distance = 40 Fog height = 20
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Fog distance = 40 Fog height = 40
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Fog distance = 40 Fog height = 100
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Fog distance = 40 Fog height = 200
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Fog distance = 200 Fog height = 20
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Fog distance = 200 Fog height = 40
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Fog distance = 200 Fog height = 100
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Fog distance = 200 Fog height = 200
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Example: Scatter GI and Scatter bounces
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This example demonstrates the effect of the Scatter GI and Scatter bounces parameters. Note how multiple scattering of light inside the volume greatly increases the realism of the image. The scene for the last image (for 3ds Max 2008) is availablehere.
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GI is off in the V-Ray settings - the fog volume only shows direct lighting.
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GI is on, Scatter GI is off - the fog does not scatter GI and so looks identical to the left image (it is lit with direct light only).
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GI is on, Scatter GI is on,Scatter bounces is 1. Notice how the fog volume is affected by the skylight. The irradiance map was used for a primary GI engine.
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GI is on, Scatter GI is on, Scatter bounces is 2. Irradiance map + brute force GI for secondary bounces.
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GI is on, Scatter GI is on, Scatter bounces is 4. Irradiance map + brute force GI.
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GI is on, Scatter GI is on, Scatter bounces is 8. Irradiance map + brute force GI.
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GI is on, Scatter GI is on, Scatter bounces is 100. Irradiance map + Light cache for secondary bounces.
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Example: Sampling parameters (raymarcher with textures)
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When any of the parameters (density, color or emission) is mapped with a texture, VRayEnvironmentFog uses a raymarching algorithm to compute the intersection of a ray with the volume.
The following examples demonstrate the effect of the Step size parameter. A Box gizmo is used to confine the volume, and the density is mapped with a Checker texture. Note how smaller values cause less noise and smoother shading of the volume. Note also that more dense volumes require smaller values of the Step sizeparameter in order to produce a smooth result, compared to more transparent volumes. In general, values for the Step size that are 2 to 3 times smaller than the Fog distance parameter work okay in most cases.
In the examples below, the Fog distance parameter is 5.0.
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Step sizeis 1.0
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Step size is 2.5
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Step size is 5.0
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Step size is 10.0
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In the examples below, the Fog distance is 20.0.
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Step size is 4.0
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Step size is 10.0
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Step size is 20.0
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Step size is 40.0
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Example: Gizmo nodes
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When there are gizmos connected to VRayEnvironmentFog, then the volume is confined only inside the specified atmospheric gizmos and the Fog height parameter is ignored.
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BoxGizmo
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SphereGizmo
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CylGizmo
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Several gizmos
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Gizmo falloff mode example
Gizmo falloff mode example
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Several gizmos; theFog color is mapped with a Gradient texture with ObjectXYZ mapping type.
