First, the ultimate goal is to get the output from a popnet into Unity. USD seemed to be a reasonable choice as I've had success exporting other animated objects out to Unity, but I'm open to other pathways.

Second, I'm still learning Solaris (previous successes were with 17.5)

Attached is a silly particle simulation that I'd like to bring into Unity. I've tried exporting the particles directly (Unity shows no children of the USD object), point instancing (same, but I'm probably doing it wrong), and using a sphere and copytopoints. The latter has had to most success, but it's really heavy, and I can't seem to get it to animate beyond a single timestep.

Any help is much appreciated.

Mark

On the sopimport Layer Save Path parameter, get rid of the “_$F”. Just set it to “$HIP/geo/particles.usd”.

The way you've written it, each frame of the particle simulation is being stored into a separate file, then all those files are being simultaneously referenced into the main $HIP/particles.usd file. USD doesn't support animated references. Instead, what you want to do is write out the whole particle simulation into a single USD file, which is what the change I mention accomplishes.