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Unlike regular volumes, aggregate volumes are fully supported as a heterogeneous interior to PxrSurface. This is the best way for creating complex effects such as occlusions inside gemstones, or a swirling ball of smoke inside a crystal ball...or Luca swimming in the ocean with crepuscular light rays!Image Removed

Fog beam layer with aggregate volumes bound to ocean interior vs final render - Luca © Disney/Pixar

Limitations

Aggregate volumes do not support single scattering. Multiple scattering is the only choice.

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