Regarding the Denoiser and the pink twinklets I had, one of the reason I now see is that Universal is not handling Transmission as well as Diffuse does.
Somehow it is not handling the combo of any specularity with Transmission:
1) Diffuse w/Transmission
Diffuse = No Transmission artifacts
2) Universal w/Transmission
Universal = Transmission artifacts
3) Thankfully, with the addition of Layered Material, I can arrange a compromise, a Layered Diffuse with a Specular Layer that can give this - full SSS with full specularity (unlike Mix Material), and almost no Transmission artifacts
Layered Diffuse + Specular = Almost No Transmission artifacts, with specular
4) Or, I can even keep the Universal as the Base layer having Specularity, but then turn off the Transmission....and then Layer a Diffuse on top of that with Transmission, which gives me this
Layered Universal (w/spec) + Diffuse = Almost No Transmission artifacts, with Transmission in Specular
I have no idea what is accurate or not, but it looks cool and has no artifacts!
So, in summary:
1 - Universal w/Specular + Transmission gives artifacts, and
2 - the 2019 Denoiser is more prone to showcasing these artifacts than 2018 Denoiser was.
3 - Layered Material offers ways avoiding the artifacts, which will bypass the 2019 Denoiser's tendancy to showcase them
** I personally feel like the 2019 Denoiser is almost too heavy with the blurring, but whatever, I can slide the Blend to what I like.
I do prefer the way the 2018 one kept detail in situations I have come across thus far, but I admit have not done any volume stuff really.... Thus, the 'value-add' of an improved volume denoising, to me, is just a heavier blur that takes away more detail. And AI is not going to fix this, it just does the denoising as it was told to do given the scene I am rendering. It will not figure out a better way to denoise it after successive restart of the render.
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