OTOY Forums

I can't recall if I've got this answered before - if I have, I can't find reference to it anywhere.

Can Octane render a mesh directly as a uniform-density medium, the way Houdini Mantra can? Or do I have to convert an enclosed mesh to a volume/VDB representation to do that?

Ideally I'd like to render sphere-particles directly using a medium shader, without rasterizing/splatting/aggregating them to a volume field.

(Edit: I see some references to a "MeshVolume Object" in forums for other packages, I'm still running a 2022 Octane build, has something been added more recently that does this?)

Huh, after much digging and a certain amount of resignation, I stumbled across it.

For anyone interested, in the Houdini context, it's the "Material Null" with a Medium of your choice plugged into it - it mentions in the docs that it's equivalent to a Material Specular with Transmission 1.0, Reflection 0.0 and IOR of 1.0, and a Medium attached... but there appears to be a distinct difference - the specular shader approach requires specular ray recursion every time a ray enters or exits the object, while the Null shader will treat the whole object strictly as Medium only, so you don't need to crank the Specular depth to massive numbers if you apply it to a dense particle object to avoid parts of it failing to receive light.

Very nice!

Hey @vortexvfx

Just wanted to say thanks for posting this solution. I was looking for the exact same thing and luckily I found your comment on here.
Cheers!