VDB Copy Out operator

The VDB Copy Out operator can be used to copy out VDB data to another event.

Unlike particles, VDBs are not sent directly from one event to another. Instead, you can use the VDB Copy Out operator to copy VDB data from one event to another. The operation you choose for the merge algorithm determines how the data will be merged with existing data in the output event. Using the VDB Copy Out operator you can create flows of VDB data that make it easier to tune specific aspects of particular grids. For example, you could copy out a velocity grid into multiple events, for fine tuning different types of velocity input, then merge them back together with multiple VDB Copy Out operators that all connect to the same event. This workflow allows you to split up grid operations so you don’t have to do everything inside one giant event.

Copy out grids

  • Grid type: controls which grid type(s) will be copied out to another event.


  • Operation: controls which boolean operation will be used to merge the grid data into the VDB of the output event.

  • Morph step: controls how much the existing VDB SDF in the output event will be morphed towards the output SDF.

Only SDF grids support morphing.

Target event VDB

  • Resample if uninitialized: if the target event VDB has not yet been initialized, enabling this setting allows you to specify the target VDB voxel size. If this setting is disabled, the target VDB’s voxel size (if uninitialized) will be made to match the voxel size of the source VDB.

If the VDB in the target event is already initialized, its voxel size will not be modified and any data copied to the target VDB will be resampled to match its existing voxel size.

  • Voxel size: the desired voxel size of the target VDB.