Volume file formats, such as OpenVDB, will allow storage of much larger datasets while being optimized for random access to volume data, which is more efficient for rendering. OpenVDB is an open source C++ library comprising a novel hierarchical data structure and a suite of tools for the efficient storage and manipulation of sparse volumetric data discretized on three-dimensional grids.
For information on working with Maya's volumetric fluids, click here. A tutorial on how to write volumes to OpenVDB from Houdini can be found here. Volumes can only receive indirect lighting from other emissive volumes when the volume_ray_depth is above 0.
Arnold Volume. Type: OpenVDB.
Custom AOVs are not currently supported with volumes.
To reduce the amount of noise in a volume, you must ensure that the lights in your scene have enough 'volume samples'.
The location of the VDB file.
Ensure that the IPR is not running when updating the file, otherwise, the bounding box will not display at the correct size in the viewport.
A list of OpenVDB grids to read and make available as channels in the volume shading context. Examples of Grid names are density, fuel, heat, temperature or velocity.
Reads a sequence of VDB files.
Specifies the frame of the sequence to be rendered.
Keframe set for 'Frame' and hashtag used in 'Filename' when using VDB sequence
Sets the minimum voxel size defined in the VDB as the step size.
More information about volume Step Size can be found here.
Volume implicit nodes can be used to load OpenVDB files for rendering volumes and implicit surfaces respectively.
Implicit type volume .vdb file
To reduce the amount of noise in a volume, you must ensure that any lights in your scene have sufficient volume samples, or alternatively that you have enough Camera (AA) samples.
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.