Is there any way to render particles as volume in cycles?

I am looking for a cycles alternative to the “halo” material in internal, that renders particles as a volume

Is this possible?

If you set your particle to instance an object that has a volume material applied (scatter, absorption or emission) - this should work.

Thanks. But is there any way to do it within the material of the emitter?
I ask because I want the particles to actually have a lower density than the surrounding material, for a volumetric lighting sort of effect. And this doesn’t work if there are objects inside other objects because at any point it seems to take the higher density value when rendering.

Do you have an image of the type of thing you are trying to achieve? It’s hard to visualise exactly the effect you are after.

What I am trying to achieve ultimately is a realistic, moving render of the aurora borealis. I thought that at the top of the scene I could have a thin box that emits particles according to a wave or other texture. The box would be very dense, but the particle information would be used to decrease the density in the right places so that it lets light through to a another, less dense, area to “catch” the light.

Does this make sense?

have you checked this thread ?
Kitten uses hair as particles, and i think the results are very good, and it’s possible do go even further!

That does indeed look very cool, but it’s not quite the look I’m going for

only way i know is with smoke.

If you don’t need smooth transitions between the densities, I believe you could do it with the boolean modifier (make the regular volume object have the particle objects subtracted from them, and either have the particle objects show, or have second volume object that only shows the intersection with the particle objects).

Though, if you’re trying to do an aurora, wouldn’t it make more sense to not have the blocking stuff, and just have some volumetric emission shapes?

Why try and do it that way though - it doesn’t really mimic how a real aurora works.

The aurora is created when a volume of air emits light due to it being hit by high energy particles. Therefore emission from a volume would be the way to go.

TiagoTiago, that’s clever but I don’t believe it’s possible to perform a boolean on a particle system, at least not without creating object instances out of the particles but in that case they no longer move.

I hadn’t thought about using emission. I think it might look pretty good, I’ll post here when I’ve done some tests