Animation rendering problems with lightcache

[exfolio]

Hello everybody, i need some advice please :

I'm working on architecture CG (outside renderings) with a small renderfarm (5servers)
I'm using BF+LC (3000 + 0,01 + 8 raytrace) as Chaos is recommending.
The speed on my workstations is fine (beetween 10 to 15mn per frame).

But i really often have some small white dots, like "reflexion pixels" : not too much (aubout 20 on a frame) but of course these pixels are always moving from one frame to another. More than this, with the denoise tool the pixels are sometimes growing and they could disappear if i'm using a strong denoise, but in this case eveything is coming more burred int the glazing.

At the moment, i'm trying to use BF + BF : it is really better but of course the rendering time is not acceptable (between x3 an x4 per frame).

Do you have the same problems, do you think it is a light cache problem and which way to try to solve ?

I'm using vray next 4.2

Thanks

[Bruce Hart]

Hey exfolio
Is there an overly bright light source or self Illuminated material nearby that is reflecting in the glossy reflection of the material? If you are using Sun & Sky - does it help if you set the sun to be invisible?

[Morne]

Make sure all your materials are vray materials, and none have a diffuse of 255,255,255

Increase AA to something like 2 and 24 or even 3 and 24

Decrease specular contribution from lights

[exfolio]

Bruce : thanks for your answer and "yes" my sun is invisible.
Morne : also thanks for your answer : ok, I need to chck all my materials, and I am gonna test.

At the moment : i can solve the problem using BF+BF but of course my rendering times are "exploding".
Chaos is saying "Set the Subdivs parameter to 3000, Sample size to 0.01, Retrace enabled and Retrace threshold to 8.0." : i'm trying to use different values for the sample size, but not big differences.

[prateekvishwa]

I am facing exactly the same issue! I was about to post it here but noticed this thread. Here is a link that shows the noise issue in my rendered sequence- https://youtu.be/ALU0_k4zjbY

My render settings are the same as yours. Initially I thought it had something to do with denoiser because output was denoised & saved for each frame unlike chaosgroup suggestion i.e to denoise them in denoiser tool. I rendered this sequence over rebusfarm & they said that due to technical issues denoiser passes cannot be saved separately in exr and they don't support .vrmg format as output.. which is why i was not able to denoise sequence in denoiser tool.

I then rendered a very small part of the sequence on my own workstation, saved output as .vrimg format & used vray denoiser tool to denoise the sequence but unfortunately this didn't help as well!