Using ORBX From Houdini

Guide to Exporting ORBX Files from Houdini for Use on the Render Network

When using Render Network in conjunction with Houdini, the accepted output format is ORBX. A Houdini scene can be exported in ORBX format from an Octane ROP node menu (Figure 1). Additional tips for preparing Houdini files for export as ORBX can be found in the Considerations for Exporting to ORBX section at the end of this document.

Figure 1: Exporting a Houdini scene in ORBX format

The Export ORBX and Alembic Files checkbox needs to be activated. The Export Mode option provides an option between exporting the entire scene to ORBX or to Alembic only. When preparing files for the Render Network, Full ORBX Scene should be selected (Figure 2).

Figure 2: Choosing Full ORBX Scene as the Export mode

The file name and location for saving the ORBX export can be determined with the Base File Name parameter (Figure 3). The .orbx file extension does not need to be added to the file name manually as is the case with typical of Houdini file saving conventions. The .orbx extension will be added automatically.

Figure 3: Naming and determining the save location for the ORBX export

The Export without Render Scene should be activated to disable Octane from rendering the scene (Figure 4).

Figure 4: Activating Export without Render Scene

It is good practice to open the ORBX file in Octane Standalone to make sure everything from the Houdini scene is exported properly. To check for rendering issues inside of Octane Standalone, click on the Render Target node in the Node Graph Editor window (Figure 5).

Figure 5: Activating a render in Octane Standalone by clicking on the Render Target node

If the exported ORBX file contains animation, the timeline will be visible in the Standalone Render Viewport window (Figure 6).

Figure 6: The Render Viewport timeline

Exporting Large Scenes

If a Houdini scene is large, the export to ORBX process can take a large amount of time or in some cases, crash during the export process. In these cases, separating the Houdini scene into smaller ORBX exports can be beneficial. There are two primary ways to do this:

• The various Objects filters in the Octane ROP’s Objects tab can be used to filter what scene objects will be exported (Figure 7).

Figure 7: The Scene Assets Collection is inactive

• Geometry nodes in the Objects network can be deactivated by turning off their Display option. Any Geometry nodes not being displayed will not be included in the ORBX export (Figure 8).

Figure 8: Deactivating Geometry node Display status

Considerations for Exporting to ORBX

• File Size - The ORBX files should not exceed 20 GB in size. If an exported ORBX file is larger than 20 GB (which can be the case with animated projects), the export can be broken down into frame ranges.

  • Tip: Brendan Prednis has created a free Houdini script (available here) for automating breaking up ORBX files into chunks of frame ranges with one click - enabling easier use of the Render Network with large ORBX files and long animations.
• AOVs - Render passes or AOVs need to be set up prior to exporting the ORBX file from Houdini. AOVs can also be set up using Octane Standalone prior to uploading the ORBX to the Render Network.

• Simulations - All simulation assets such as particles, fluids, hair, etc. should be baked prior to ORBX export.

• Double check Pyro or VDB simulations in Standalone prior to uploading the ORBX to the Render Network. This is to ensure that the proper VDB grids are loaded in the ORBX file.