Weird artefacts in low light situations

[Cinemike]

Win 10, R19.053 Studio, Corna Beta 1 Release

Load the scene and render, there you are: artefacts.
Well, the only appear if you use a sky with really, really low settings, but when playing with a situation only lit by candles (and when I wanted to add a bit fading skylight) I stumbled across them.
The sky's intensity is 0.001, with a brighter sky the artefacts won't appear. It does not matter either if I use an intensity of 1 and REALLY lower the color values in a Rawa-Fake sky or if I use a Corona Light material with an HDRI where I really lower exposure or intensity - the artefacts will come over you.

Just saying.

CU
Michael, trying to break things

[TomG]

Interesting, they don't show up in IR.

[Cinemike]

Interesting indeed, I did not try it with IR. The original scene is too heavy for my modest PC to make sense with IR. But this gives hope it is something that can be fixed.

[TomG]

I am sure it will lead to diagnosing and then fixing it :) There have been other threads about things that look different in IR vs final render, so perhaps the underlying cause is the same. Just wanted to note that IR didn't have the artifacts as that may point to the cause and fix!

[Cinemike]

I am sure it will lead to diagnosing and then fixing it :) There have been other threads about things that look different in IR vs final render, so perhaps the underlying cause is the same. Just wanted to note that IR didn't have the artifacts as that may point to the cause and fix!

I appreciate this!
But it could have been a limitation with extremely low values as well (I keep stumbling over "limitations" with other software all the time ;)), so I am glad it is not (because of the IR) and I am glad it will be taken care of :)

[Cinemike]

Any new insights on this one?

[Beanzvision]

It seems they are still there. Only the IR didn't show these artifacts. Strange. We'll definitely look into.

Preview render:


IR:


VFB:

[burnin]

The cause of the issue is the Sun intensity of 'Corona Sun' object at value: 0.001. Setting that to 0.005 already works fine.
I suspect precision.

A word of advice: It's better to apply tone mapping techniques to achieve wanted "Low Light Photography" style.


& a note for someone special ;)

Since IR (interactive renderer) doesn't match the final renderer (it doesn't applies same settings), for the sake of clarity, i call it IPR (Interactive PREVIEW Renderer) -  which also helps users to be aware of inconsistencies.

Got nothing to do with Arnold or Solid Angle. In my eyes their publicized works (PR, manual, tuts, articles, papers...) are a 'master template' - an example of how to present self (the profession) in simple & understandable manner.

[Cinemike]

The cause of the issue is the Sun intensity of 'Corona Sun' object at value: 0.001. Setting that to 0.005 already works fine.
I suspect precision.

A word of advice: It's better to apply tone mapping techniques to achieve wanted "Low Light Photography" style.

Yes, i already suspected a precission issue above, on the other hand with differences between the IR and the PV, it is still worth it to investigate. You never know if you don't hit a more general issue to fix.
As for your advice, the (actual) image is long finished. But I am still happy I tried what I did, so I could find the limits of the software - and searching for bugs sometimes requires steps you would not go normally ^^

[iacdxb]

Today I was also having same issue in light setting. IR does not show reflection/glossiness but in render.... it shows.

Same happens with Corona Mix, that I posted already.

...

[burnin]

Today I was also having same issue in light setting. IR does not show reflection/glossiness but in render.... it shows.

Same happens with Corona Mix, that I posted already.

...

Something like what's mentioned in  "IPR & Final render differences"
Also, have you checked "Are there any differences between regular and interactive rendering"?

[Cinemike]

It's alive, Jim!

[Beanzvision]

This old chestnut! ;) Thx