flickering pampass grass

[Daniel Kurth]

Hi all,
first I will show you a small animation of mine.

[Daniel Kurth]

Second now the description.

First, thanks to Will Gibbons for his free files and tutorials!
But also thanks to Sam Gwilt from "Sam does Design" or Liam Martin!
All your tutorials helped me and I'm sure others enormously in working with keyshot!

Concerning the lighting I used Will's freely available studio environment.
How to display the pampas grass in the best possible way I learned from Sam and Liam.

In the single images it comes out really nice.
But as you can see, the pampas grass flickers during the animation.
And yes a bit flickers the shadows inside the shelf too. But that's not sooo terribly bad)

In another post https://forum.keyshot.com/index.php?topic=27439.msg114975#msg114975 with a similar error image it said that the denoiser should be off when rendering animations. It is. And I also set the samples higher than for the single frames I've made before.
Also an area light should not be visible in shadows.
It isn't.

And animated I have both variants. So CPU or GPU.
The result was the same for both variants.

Does anyone have a tip?

I use keyshot 10.2
CPU = i7-8700 CPU with only 12 cores 
GPU = Quadro RTX 4000, 8GB
Rendering mode = Interior mode (maybe I should try product mode next)

[Will Gibbons]

I think this is from the denoiser. Are you using it? If so, it probably is causing the issue. Or, it could be GI... doesn't seem to be caustics, but correct me if I'm wrong.

You didn't mention, are you rendering in max samples (per frame) or max time (per frame)? It matters, because in theory, if using the first choice, then the samples will be the same per frame and things should not flicker. However, depending on how KeyShot is calculating GI or denoising, that can cause variation on a per-frame basis. This is when I sometimes have to rely on post production and not dealing with these in KeyShot.

[Daniel Kurth]

Hello Will!
Nice to meet and here from you! 

Well first I had the denoiser on.
However, I did go through another test before you wrote here.
GPU mode = on
Denoiser = on+ product mode, instead of interior mode.
The grass was not flickering but other things in the background 
After that I tried this:
GPU mode = on
Denoiser = off + product mode again
Nearly the same result as with Denoiser = on.
You can see it in the GPU animation which is attached in this thread.

The next test was
GPU mode = on
Denoiser = off + product mode
And this is the best result until now.

PS:
I choosed "max samples per frame = 32" (see attached screenshot)
Caustics = off
GI = Aversis_Village-lawn_3k.hdz as the hdri background light + one small pin for simulation the sun + a picture-pin including the Aversis_Village-lawn_3k picture,.... mmh I don't know exactly why 
I think I retouched the very white sun area in the hdri picture with that. Because this Pin is very close to that area.