Jeroen Lapre'

We are trying to render a volumetric galaxy, but /tmp/houdini_temp/usd_renders/ directories are filling up on worker nodes on our render farm and our render jobs are failing.

It appears that Karma USD renders that include VDBs leave a copy of the VDBs in the /tmp/houdini_temp/usd_renders/<jobSubDir>.

The USD Render ROP/Usd/Delete USD Files menu defaults to Delete if Saved to Temp Directory

Please find attached a simplified example.

There are 2 USD render ROP lops.
One renders the polygonal version of Crag.
This renders and then deletes the /tmp/houdini_temp/usd_renders/<jobSubDir>
So far so good.
However, the other USD render ROP renders the VDB version of Crag.
This leaves a copy of the VDB in /tmp/houdini_temp/usd_renders/<jobSubDir>.
The post-render clean-up deletes the USD files, but does not delete the /tmp/houdini_temp/usd_renders/<jobSubDir> dir, as the VDB is still in there.

I'm assuming this is a bug?

In the meantime, we'll try to write our own post-render script that more aggressively deletes /tmp/houdini_temp/usd_renders/<jobSubDir>

Thanks

Siavash Tehrani
In general it's not good practice to leave geometry as ngons, especially if the mesh has holes. Aside from giving some renderers trouble it can also cause issues with geometry interchange. For example, certain importers will simply ignore ngons and leave you with missing faces.
If you can, triangulate ngons in Maya. Otherwise fix it in /obj or a SOP Modify in LOPs. One way is to create a group with the Group Expression SOP and the expression @numvtx>4, and then run that group through a Divide SOP (enable Avoid Long Edges). This will leave your quad topology alone and only triangulate the ngons.

Thanks, Siavash. I'll give your suggestion a try. This is an old model by a volunteer while they were still learning how to model in MAya. They wouldn't make that same mistake these days.
I'm just curious why the original geometry looked ok in openGL and in Arnold in Maya, but not Karma.

In the meantime, I found a workaround.
I use the PolySplit SOP to divide the large flat polygons around the hole into smaller polygons.
Which is time-consuming and labor-intensive.
Maya and Arnold are able to render the original geometry without this problem.
I'm curious to know why Karma has issues with it.