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In addition, if the OpenVDB files are heavily detailed and it is anticipated that the files may be overly dense for what is required, the VDB files can optionally be preprocessed with vdbmake to generate mipmaps. Doing so may result in lower peak memory requirements as only lower levels of the mipmap pyramid will need to be loaded by the renderer. On the other hand, it may often be the case that loading two fine levels of the mipmap pyramid may use more memory than simply loading the base level of the pyramid; the OpenVDB file format in particular can make the advantages of mipmapping less obvious than would be seen in other potential volumetric file formats.

While typically the PxrPathTracer integrator can only render one global volume aggregate, any number of aggregates can be created. These aggregates can be bound as the interior to a closed dielectric surface that uses the PxrSurface material. Unlike regular volumes, aggregate volumes are fully supported as a heterogeneous interior for 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.

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