Volumes

 

Volumes are objects made of density, such as fire or clouds. 

Rendering of volumes should not be confused with Atmospheric Volume Scattering, which is a global effect.

Volumes can only receive indirect lighting from other emissive volumes when the Volume Ray Depth is above 0.

Volume Formats

  • Rendering volumes with HtoA only works with OpenVDB files or VDB primtives.
  • You can also develop your own volume plugin with the new volume API, see Implementing a Volume DSO
  • It is also possible to render particles as volume, with access to particle attributes as user data.
  • You can also render polymeshes as volumes.

Volume Nodes

  • Arnold Volume - Arnold volume object node.
  • Standard Volume -  Shader that defines the volume shading properties.
  • Volume Sample RGB and Float - Shaders that sample a volume channel.

Render Quality

Several parameters affect the overall quality of volume rendering:


Volumes and Atmosphere Volume

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.

Left: floor plane geometry hidden. Right: floor plane geometry visible. Fluid renders incorrectly. Click images above to view animation.

 

Further examples

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