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PxrVolume is a material that can be used to render volumetric effects which can vary wildly in complexity, including:

• Constant fog (a constant homogeneous volume with single scattering);
• Smoke (a heterogeneous volume where single scattering suffices);
• Fire (a heterogeneous volume with emissive properties);
• Clouds (a heterogeneous volume where multiple scattering is usually required)

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