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If the data source for the volumes are OpenVDB files, the density signals comes directly from the file, and is not increased by shading, then it is highly suggested that the new Attribute "volume" "int dsominmax" be set to [1]. Doing so will allow the renderer to build an acceleration structure from the volume much faster using minimum and maximum values of the density, either by reading prebaked data directly from the VDB file or generating it on the fly at render beginas the volume is loaded. This results in much faster time to first pixel as the renderer no longer needs to run density shading in a preprocess upfront before shooting rays. If the volume density is derived procedurally in a shader, then dsominmax should be set to 0. An exception exists for cases when a quick density manipulation is desired: impl_openvdb supports new controls that allow for global scaling and shaping of the density while still supporting the dsominmax 1 optimization.

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