USD Export Support
The Universal Scene Description (USD, .usdc) format is designed for storing generic scene data and is the preferred format to export a FLIP Fluids addon simulation. Exporting to USD can be useful for archiving simulation data or for submitting jobs to render farms that do not support the FLIP Fluids addon.
FLIP Fluids simulations can also be exported to the Alembic (.abc) format, however, exporting to USD is preferred as Blender's USD exporter supports more features and full FLIP Fluids export compatibility.
- How to export to a USD file
- How to import a USD file
- Important Notes and Known Issues
- USD export for use in other software
Use the File > Export > FLIP Fluids Universal Scene Description (.usd*) operator to automatically set up the USD export and to ensure a stable and correct export of the simulations. This operator also adds optimizations that can speed up the export process compared to using the default Blender USD exporter, and works around current bugs in Blender that affect export correctness and stability.
| Export FF USD | Automatically launch a new command line window and start the USD export. After launching the export task, you may close Blender and the exporter will keep running. The command line window will display info about the export and the progress of the export. Notes: Depending on system security settings, this automatic command line export feature may be considered a security risk and may not start. If this is the case, use the Copy Command to Clipboard operator (see below). |
| Copy Command to Clipboard | Click to copy the command line USD export command to your system clipboard. After copying the command, you may paste this into your system's command line terminal to start the export task. |
| Frame Range Mode | Frame range to use for USD export. Timeline Use the start and end frame range from the timeline. Custom Use a custom start and end frame range. |
| Export Meshes | Select the fluid surface, fluid particles, and whitewater foam/bubble/spray/dust meshes that will be exported. If the surface, fluid particles, or whitewater features are disabled, any enabled meshes in this section will be exported with empty data. |
| Export Attributes | Enable to include the corresponding simulation attribute in the USD export. Attribute data will be available under the vertex or point cloud attributes of the USD export. Attributes are required to be baked before export. Tip: to verify that the USD export contains an attribute, this data can be viewed in the Blender Spreadsheet Editor after importing the USD file. |
Use the File > Import > FLIP Fluids Universal Scene Description (.usd*) operator to import and set up a USD cache. This operator automatically sets up the import with geometry node modifiers for rendering the simulation meshes and transferring enabled attributes.
There are known issues and limitations in Blender that can affect USD export of simulation meshes:
- A current bug in Blender is resulting in the entire USD export being stored in RAM. If the FLIP Fluids cache is larger than the amount of system RAM, the export will run out of memory before completion. This issue has been reported and confirmed here, and a fix appears to be in development: #156402.
- The USD exporter will export the simulation geometry based on what is loaded into the viewport and is not aware of any render display settings. To ensure that the simulation is fully exported, set the viewport display/visibility settings to load the Final version of the mesh.
- Blender's USD exporter can only export Mesh type data for the fluid surface and Point Cloud type data for the fluid and whitewater particles. If you have any custom geometry node modifiers that convert the objects to another data type, you will be required to remove these modifiers manually before using the export tool.
- The USD exporter supports exporting generic attributes and all FLIP Fluids addon attributes. If you have custom geometry node modifiers that add attributes to the simulation objects, these will automatically be exported.
- If you receive warnings during export similar to
WARN (io.usd): ... update_bounding_box: Bounding box is null!, these can be ignored. These are harmless warnings generated by Blender that one of the meshes contains no geometry and a null bounding box, which is common for simulation meshes.
USD export support is a new feature as of FLIP Fluids 1.8.6 and had not yet been tested in other software.
The resulting USD file after export works well for importing back into Blender, but we cannot guarantee that this will work for importing into other software that use different standards for how the USD export is structured. As USD is a generic container for storing scene data, you may be required to develop your own pipeline for transferring USD files from Blender to another software.
If you would like to test USD export using the FLIP Fluids addon in your workflow, try our free demo.