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Walt Disney Animation Studios Cloud Data Set available here. Tutorial here.


The standard_volume is a physically-based volume shader. It provides independent control over volume density, scatter color and transparent color. Blackbody emission is used to render fire and explosions directly from physics simulations.

Each component can be controlled by a volume channel coming from the volume object, with other parameters acting as multipliers on the channel. Optionally the channel can be left empty, and a custom shader like Volume Sample or a procedural texture may be connected instead, to manipulate each component with more control.

However, be warned that the evaluation of a shader network for volume rendering is much more expensive than for surface shading because the shader network is called many times per ray, once per ray march sample. So, in a production environment, it's best to use as few shaders as possible, ideally having just the Standard Volume standard_volume shader doing all the work.

Info

The images in the examples below use a GI Volume Depth of 8 (defaults to 0). This is useful when rendering volumes such as clouds for which multiple scattering has a large influence on their appearance.

Tip

It is recommended that volume shading networks are kept as lean as possible. This is important for to render times in the volume context because it is evaluated so often.

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  • None: emit no light.
  • Channel: emit light using a specified emission channel, or using a shader connected to the emission rate or color parameters.
  • Density: emit light using the density channel, modulated by an optional emission channel.
  • Blackbody: emit color and intensity based on temperature, for rendering fire and explosions.
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Emission is the rate at which a volume emits light. If a density channel, emission channel, or blackbody channel is used for emission, this acts as a multiplier to decrease or increase the emission. Alternatively, if no so such channel is used, a shader like a volume sample or a procedural texture may be connected to this parameter to control where light is emitted.

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(Emission Mode: Blackbody)

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

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In Channel emission mode, the emission channel to sample the emission rate from.

When not empty, this channel will be used to sample the emission values for the volume instead of the Emission parameter. The sampling tab has additional parameters to control how data is sampled from volume channels.

Note

When using the Channelchannel emission mode, ensure that the emission attribute is driven by a VDB grid. If it is a fixed parameter value, you may get artifacts.

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Connect a noise texture or other shaders here to displace the volume, similar to displacement on surfaces. This can be used to add additional detail to the volume or to warp it. The connected texture will be applied as an object space offset to the volume sampling position, for all volume channels.

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Tip

When using the noise shader with displacement, ensure that its mode is set to vector.

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Noise shaders -> displacement

Tip

When using displacement, ensure that the volume_padding of the volume is increased to account for the increased size of the volume.

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