Are there any tutorials on using volumetric lighting in houdini? I'm used to using mental rays parti volume for underwater volume lighting, how would I go about that with Mantra. I've tried searching for volumetric lighting but nothing obvious is coming up. Could be I'm missing something, or :?

At the obj level hit the tab key and type atmosphere.

You can also create a fog volume that encompasses your scene.

Cheers, I must of missed that, so if I'm understanding it correctly you drop down the node and give it a material shader?

In which case I've tried using the uniform fog shader and that seems to be easy enough, doesn't impact render times, and at a glance creates cheap distance fog effects without having to do any compositing.

V_Lit Fog on the other hand, which I think provides the volumetric effects I'm after seems to be ridiculously slow with even the most basic geometry, so is there any tips or tricks to get it working properly since there's very few settings on the shader itself?

I tried the fog volume (box > create volume) and used a volume ramp node to adjust the density, and that rendered a lot faster. Will have to have a play around with that some more but that's still only volumetric shadows? It does look good though so I'll keep playing with that.

Sorry to be a pain but what's a good workflow to create the kind of god ray lighting for a light source in fog/underwater. Am I on the right track?