I exported a volume in USD format. I creating the pyro material in the material library and assigning the material. Nothing shows up in the viewport. Even without assigning the material I don't see any volume or even a bounding box. What can be done here to see volume primitives in LOPs?

Volumes are working fine for me. Have you checked that your volume has reasonable data?

Does my scene work for you?

Your setup does work for me, however when I use my own file(a bgeo containing multiple fields), it does not work. In this setup I just replaced your file with mine, and set the fields parameter to density. When the material gets assigned the volume no longer appears in the viewport.

Thanks for your help

I don't have issue importing my own vdb bgeo file.

I think it's as jsmack said -

Have you checked that your volume has reasonable data?

Maybe post that file or screen shot an info panel on your vdb.bgeo on a file import node or something like that.

The data is all correct, it appears in the viewport up until I assign the material. Once the material gets assigned it is black. This doesnt happen if I use the VDB that jsmack provided.

Attaching the bgeo file here with a section of the volume.

Just throwing darts here…On your volume Lop in your fields parameter do you get anything if you also put in vel, heat and fuel?

How about also increasing the density scale on the shader itself.

I think it's was just a matter of resetting the material assignment node.

When I initialy referenced your bgeo file you posted, I got nothing once on the material assignment node flagged to visible.

If I cleared the assignment and re-entered, it came up and rendered.

Interesting, are you rendering with Karma? Maybe that's my issue? I can see the volume in Houdini GL but doesn't look shaded correctly according to the pyro settings. Attaching hip file. The output node is in sops under /obj/pyro_import/import_pyrofields save to file.

I got it to work by resampling your voxel size.

So, as jsmack originally said it's a matter of having the right data.

Hey BabaJ,
I really appreciate your help, I do see the volume rendering now, but it looks like only density is taken into account. Here is the mantra equivalent using the file you send, but swapping the sop import node to be the pyro fields node. Notice how the temperature and heat fields are not rendering correctly in the karma example.

Also I don't believe the color is working either, because I had smoke color set to green in that file and it still renders as greyscale.

That's probably because in the file I posted I had in the material assignment:

/volume1/sopimport1/materials/

once I specified the actual shader:

/volume1/sopimport1/materials/fireball

Things seem to be ok then.

Holy toledo! That worked out thank you so much BabaJ!