Hello,
I rendered a small test scene to test volumetric lighting in cycles and encountered a problem: The render was really noisy, although I cranked up the sample size to 2500 and chancing the Clamp Indirect settings didn’t change very much.
After that I tried to render an even simpler scene and got this result with 5000 samples and Clamp Indirect 3 (also only with direct light settings):
Is there anything to do about this (maybe tweak some settings) or is this just how cycles is?
Not much you can do. Your lighting scenarios are really bad for a path tracer - especially when combined with volumetric scatter.
Portals may help if you were using HDRI environment lights to light the scene - but you are never going to get a noise free image with that type of lighting and a few hundred samples until Cycles gets MLT, Bidirectional or both (if it ever does).
In the second render I even used portals and a spotlight lamp. I did the lighting like, if you know him, Andrew Price from the blender guru volumetric lighting tutorial. Nevertheless, thanks. I guess I have to live with that.
Unless something has changed recently…Portals doest work with point lights or spot lamps - only environment HDRIs.
