Hi all,

I'm working on a cycles render with some smoke in it and running into an odd problem that I haven't seen in any tutorials on the subject. I have my smoke flow object set to invisible but it still showed up in the render as a slightly translucent object until I gave it the same material as the smoke domain object had. Now I am getting a faint edge line between the flow object and the rest of the smoke in the domain (see screenshot).

Sorry I didn't take any shots of the smoke setup but if I recall correctly (it's rendering right now) I had the volume set to produce smoke at a slightly higher rate than the surface (I can't remember the name of this setting off-hand, sorry again).

Has anyone else run into this issue, or have any ideas what might be causing it? I can just try playing with the settings but volumetric test renders are so slow on my machine that it would take me all weekend to figure it out by trial and error so I thought I'd ask.

Some possibilities that have occurred to me:

1. Maybe the rate of smoke creation has to be the same for the volume and the surface?
2. Maybe just upping the smoke quality would fix it?
3. Maybe my shader is just plain wrong (attribute node with "density" entered in the box feeding into the density of a volume scatter which is feeding into the volume output for the material)?

Thanks for any help, Mark

I'd be looking at that object's casts-shadows property, perhaps.

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

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Thanks @RobynsVeil.

I fiddled with the settings some and let it run another hour and that line went away, but I changed so many things at once that I am not sure which one fixed it (or maybe none of them did - I now think that maybe it just needed a lot more samples).