Flickering and artifacts in low-light animation scenes

[suzanne_doherty]

Hello,

I'm still getting to grips with Vantage.

On well lit scenes, I have barely any flickering, but on dark scenes, where a product is illuminated in a subtle way with spot lights, there is really noticable flickering. It generally appears on metalic, non glossy materials, where GI is needed to light these areas.

I've messed around with the render settings, but I can't seem to get a clean render, but maybe I'm missing something?

If I render with Vray CPU, using LC, BF, the issue disappears, but it's 3 mins a frame, compared to 10 seconds for Vantage.

Can anyone give me some "ultimate" rendering preset I could try?

Thanks

[vladimir.nedev]

Can you show us how this flickering looks or maybe even send us a sample scene ?

Greetings,
Vladimir Nedev

[npg]

You mentioned spotlights. If you have many light sources you could try the "Direct light reservoir resampling" option (with or without spatial importance in Advanced). Alternatively, just increase the sample count under "Enable lights tree". Both of these improve light sampling with some performance cost.

[suzanne_doherty]

Can you show us how this flickering looks or maybe even send us a sample scene ?

Greetings,
Vladimir Nedev

Thank you. I have just emailed you the files, can you let me know when you receive them please?

[suzanne_doherty]

You mentioned spotlights. If you have many light sources you could try the "Direct light reservoir resampling" option (with or without spatial importance in Advanced). Alternatively, just increase the sample count under "Enable lights tree". Both of these improve light sampling with some performance cost.

I think there's about 9 lights (8 spot lights, 1 vray plane light).

[vladimir.nedev]

Thank you. I have just emailed you the files, can you let me know when you receive them please?

Thanks, I got the scene.

You have lots of glossy metal/plastic parts reflecting in one another, which creates difficult to sample noise.

Increasing the light tree samples might help a bit, but you will still need a lot of "AA samples" (the Samples in the "High Quality Render Dialog").
You can try lowering the number of reflection bounces to a value that still looks good but renders faster.

If you lower the "clamp secondary rays" value from 200 down to 20 or even lower, the reflections will get clamped and the noise will clear faster.
Another option is to use a VRayOverrideMtl for the "Aluminium" material and replace it with a simple diffuse material for reflections.
The realism of the result will suffer if you do one of these.

Greetings,
Vladimir Nedev

[suzanne_doherty]

Thanks, I got the scene.

You have lots of glossy metal/plastic parts reflecting in one another, which creates difficult to sample noise.

Increasing the light tree samples might help a bit, but you will still need a lot of "AA samples" (the Samples in the "High Quality Render Dialog").
You can try lowering the number of reflection bounces to a value that still looks good but renders faster.

If you lower the "clamp secondary rays" value from 200 down to 20 or even lower, the reflections will get clamped and the noise will clear faster.
Another option is to use a VRayOverrideMtl for the "Aluminium" material and replace it with a simple diffuse material for reflections.
The realism of the result will suffer if you do one of these.

Greetings,
Vladimir Nedev

Thanks Vladimir for looking at the files, I'll give your comments a go and see if I can make any adjustments.