I am getting light flickering and geometry penetration when rendering in EEVEE with volumetric lights.
Since an image is worth 1000 words, here is a visual example of what I’m running into:
You can see some of the flickering around the 7 second mark with the lights on the left ceiling in the distance and the sub-floor lights, again at the 13 second mark the flickering light above the door is not supposed to be flickering at all, it’s just a spotlight, and finally around the 28 second mark on the right of the frame where the light is penetrating the geometry and flickering.
I’ve tried pumping up the samples but I can’t seem to get a satisfactory result.
I was wondering if there is any way to fix or at least limit this as much as possible, or if this is just the way EEVEE works with Volumetric lighting?
Many thanks for any ideas on how to tackle this issue. If I can solve this I am good to go for my project.
Ok, I’m getting better results by both increasing the Volumetric samples and putting in a fairly high value of 10,000 in the Light Clamping setting, but I am not sure of exactly what the Clamping is doing. The Blender manual doesn’t really have any guidelines on how to set the Light Clamping values so I’m not sure what they should be without running a lot of tests to try and figure out what setting range is appropriate or if there are other negative impacts on the quality of the render by going too high with the values.
Can anyone shed some light on how to determine a proper value for the Light Clamping volumetric settings in EEVEE?
It controlls how smooth the lights in volumetrics are.
0 is disabled. Over 0 is super diffuse and higher you go the sharper the area becomes again.
If you set the values to low, but not 0 it might help with flickering due to there being no pronounced volumetric lights next to light sources and it’s distributed more evenly.
Can’t test it atm so I hope it isn’t changed recently.
Just speculating, but if your scene is built to scale then reducing the volumetric end distance (default 100m) should result more samples being in the range your scene seems to be in and might help a bit.
Thank you for very useful info. I wish the Light Clamping setting had a more narrow defined range (like 0, and 1-100) as opposed to an unlimited range, but now at least I can wrap my head around the basic concept.