Rollover image 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's terms). Currently, atmosphere_volume does not compose well against volumes. This is because atmospheres 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. |
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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.
atmosphere_volume can also be selected by showing Dag Objects Only in the Outliner window:
