Hey, does anyone know if it's possible to add something like LPE tags to geometry lights for Karma XPU? To split up render AOVs by light contribution. As far as I can tell according to the docs it might be impossible and the only workaround I found is for Karma CPU only, unless there's something new in H20+ that I haven't found.

Would like to know this as well.

Geo light LPEs are supported in 20.5 for both XPU and CPU.

Geo lights must have the "Treat as Light" tag enabled and have an LPE Tag. They must also be included in the Geo Light Primitives Paths on the Karma Render Settings LOP so they'll be found by the "Split by LPE Tag" option.

Here's an example hip.

npetit
Geo light LPEs are supported in 20.5 for both XPU and CPU.

Geo lights must have the "Treat as Light" tag enabled and have an LPE Tag. They must also be included in the Geo Light Primitives Paths on the Karma Render Settings LOP so they'll be found by the "Split by LPE Tag" option.

Here's an example hip.

Thank you! This already helps a bit, however when I follow the steps outlined in your hip file but in my more complex scene, it seems to just... not work on one of my geometry lights. See screenshots for examples, the "fire" tag works but the "portal" tag does not.

I wonder if I'm missing something...? I don't see why one of the lights would work while the other doesn't. I can confirm that I see the LPE tag and the treat_as_lightsource primvar set to 1 on my "portal" light, and yet it doesn't appear in my AOVs.

Just to add onto the last post, the main difference I'm finding between working geometry lights and not working ones (in terms of generating AOVs, to be clear the lights are all contributing in the main beauty render) is that the ones that aren't working are loaded via asset reference nodes.

The working light group, the fire geometry lights, are loaded in via a Sublayer LOP.

The common denominator between the NOT working geometry lights is that they were all cached out to .usd files using the standard Component Builder workflow with default export settings.

The working geometry lights however were manually imported to LOPs using SOP imports and cached out using a file cache node.

I've tried importing one of these assets using a Sublayer LOP instead of the asset reference LOP, but it's still not generating a separate set of AOVs.

Is there some sort of limitation here in which types of primitives can be used as Geo Light Primitives in the Karma Render Settings node?

It looks like you have set the Geo Light Primitives Path to "/FG/lights/geo/portalGeoLight/*" on the Karma Render Settings LOP instead of "/FG/lights/geo/portalGeoLight" which is the prim with the LPE Tag - that might be the issue.

I think you're right. After far too much troubleshooting for my own good I finally landed on a very simple solution - adding the LPE tag in a Render Geometry Settings LOP instead of the LPE Tag LOP. I totally missed this option in the Render Geometry Settings node before, but this way I can use wildcards to exactly match the primitive path I'm using in the karma render settings node, and it seems to be working as expected now!

Thanks again very much for the help and hip file, it really helped a lot