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“C:\Users\thinsoldier\Desktop\BlenderWorkPC\2020\3ds-streetpass-mii-plaza-restaurant\Open\open4-extralights-v03.blend”
For a year and a half I’ve been trying to find a balance between render time and noise on this scene. Adaptive Sampling, which reduces render time significantly, was screwing up the denoiser and making the counter top look like smeared mud. Finally found 1 setting I don’t remember ever tweaking before and the problem went away. But, I bet if I go through my notes I’ll find I did in fact spend a whole day playing with that setting at some point. I know I experimented with Min Samples extensively but I don’t think I ever touched Noise Threshold. I’ve only tested it in CyclesX so possibly it is still a problem in regular Cycles.
This problem has been plaguing me since early 2020. If adaptive sampling was on and set to zero the denoiser would fail hard. Today in CyclesX I discover that if I change Noise Threshold to just above zero not only does this problem go away but it renders in a fraction of the time. However, a new problem is introduced with the shadow of the stairs on the upper wall. That shadow looks much better if I leave Noise Threashold at zero.
What makes this extra frustrating is this problem caused me to abandon Jonathan Lampel’s advice about using real world lumens and exposure to make lighting in Blender easier. I only got this problem in this scene after following that advice and using his Extra Lights add-on. I thought the advice was the problem. The point lights over all candles are real-world strength, the exposure was set relative to those lights. All this time I was under the impression that having the lights so weak and the exposure so high was causing the problem, but all I needed was one click on Noise Threshold to mostly fix it.
Forgot to mention in the old cycles the adaptive sampling was never applied to the viewport. That was only fixed in CyclesX.
