Hello,
I'm trying to render a USD asset and get the Pref AOV working in SOP. I can see the AOV render as it should if I unpack the USD, but not if I render it packed. It works in LOPs and I can see the attribute primvars:Pref, but when I try and render it via SOP it just wont show up until I unpack (which is not a solution).

Any idea on how to get that attribute to work in SOPs?

regards
stefan

Just out of curiosity why can't you unpack?
Think its up to the renderer how they handling the packed data if they able to extract the attributes.
When they load in houdini usd packed prims don't think possible to get anything else than P, path and name.
So probably is a render setting somewhere to enable this or renderer just not able to do it i think

A few things why you should avoid to unpack (regardless of Alembic or USD files)

1. if you unpack it's no longer a procedural which means (in our case with Arnold) that the Arnold export would create very large render files. The alternative is to unpack and write out the geo as a native ass.gz file for arnold, but if you have large animated spaceships or vehicles this becomes a ass sequence which can be very big on disc.
   
2. adding a "pack" after a "unpack" doesn't mean it's a procedural anymore. It will still do the large export as explained above.
   
3. when you unpack the raw data much be sent to the renderer which then has to pack it to it's own format before rendering.
   
4. The viewport will be filled up with 100's of millions of polygons if each asset in a scene needs to be unpacked.
   

So far I've tested with Arnold and Renderman to get Pref to work with usd assets that has Pref as a attribute. I know it's a bit odd to use USD assets in SOP, but we are not there yet to use LOP as our render platform.

regards
stefan

StefanA
So far I've tested with Arnold and Renderman to get Pref to work with usd assets that has Pref as a attribute. I know it's a bit odd to use USD assets in SOP, but we are not there yet to use LOP as our render platform.

I'm confused, you're rendering packed usd prims directly? I thought that didn't work at all. In my tests with mantra they don't show up. You need to render USD with solaris via Husk. I remember there being very rudimentary support provided by the pixar usd plugin, but there was no way to assign materials.

A plugin like arnold or renderman probably has no idea what a packed usd prim is, and unpack it when rendered.