Atmosphere Volume

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This shader simulates light scattered by a thin, uniform atmosphere. It produces shafts of light and volumetric shadows cast from geometric objects. It works with point, spot and area lights, but not with distant or skylights. This is a scene-wide volume shader (or an atmosphere shader in Arnold terms).  

  • atmosphere_volume used to be called volumetric_scattering and should not be confused with volume rendering of fluid type objects.
  • atmosphere_volume only works with 'local' lights that have a precise location and size and inverse-square decay. It does not support lights at an infinite distance, such as the Skydome light or directional light.
  • Currently, atmosphere_volume does not compose well against volumes. This is because atmosphere's return a single flat result that is opacity mapped on top of whatever is in the background of the pixel.

    Atmosphere Volume cannot 'penetrate' through the cloud volume

atmosphere_volume should be composited using an 'additive' mode such as 'screen' because volumetric scattering is the light that cannot be represented in the alpha channel.

Enable Matte enabled for standard_surface shader assigned to wall geometry (left). Atmosphere Volume render composited using 'screen' (right). Rollover images.

 

The example below demonstrates the effect of atmosphere_volume through a medium. It consists of a polygon plane with a circular ramp texture connected to the opacity of a standard_surface shader. The spotlight is pointing at the plane and atmosphere_volume is enabled.  

 Polygon plane with circular ramp texture -> opacity of a standard_surface shader

An example scene can be downloaded here.

 

The attributes are divided into two groups and are described in more detail in the pages below:

  • Atmosphere Volume can be found in the 'Atmosphere' menu under Environment in the render settings window.

 

  • Once Atmosphere Volume has been enabled, it can be selected again by showing Dag Objects Only in the Outliner window:

Example

The example below demonstrates the effect of Atmosphere Volume through a medium. It consists of a polygon plane with a circular ramp texture connected to the opacity of a Standard Surface shader. The spotlight is pointing at the plane and Atmosphere Volume is enabled.

 Polygon plane with circular ramp texture connected to the opacity of a Standard Surface shader

Atmosphere Volume used to be called Volumetric Scattering and should not be confused with volume rendering of fluid type objects.

Atmosphere Volume only works with 'local' lights that have a precise location and size, and inverse-square decay. It does not support lights at an infinite distance, such as the Skydome light or a directional light.

Currently, Atmosphere Volume does not compose well against volumes. This is because atmosphere's return a single flat result that is opacity mapped on top of whatever is in the background of the pixel.

Atmosphere Volume cannot 'penetrate' through the cloud volume

Atmosphere Volume should be composited using an 'additive' mode such as 'screen' because volumetric scattering is the light that cannot be represented in the alpha channel.

'Enable Matte' enabled for Standard Surface shader assigned to wall geometry (left). Atmosphere Volume render composited using 'screen' (right). Rollover images.

 

 

 

Further Examples

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