Flickering problem using DOF

[gabriel_chahouddealmeida]

Hi, guys!

I'm running some animation tests with DOF on, but the flickering problem is persistent: The video example with the flickering problem

This is what I did to try and solve it:

• Increase samples to 100 (I was using 50 at first)
• Switch the denoiser mode
• Turn off the Light Cache option
• Increase the FPS
• Increase the resolution

*render and video quality are both set to high.

None of that worked so far...

What should I do to prevent that from happening?

Best,
Gabriel Chahoud

[npg]

Does this mean that there is no such flickering with DOF disabled?

What did you mean by "switch the denoiser mode"? The NVIDIA denoiser with "reduce flickering" should be the best option for animation.

What light sources do you have? Are there many lights in the scene?

[gabriel_chahouddealmeida]

Hi, Nikola!

• There is still some flickering when the DOF is off, but it's a lot stronger with the DOF on.
• Switching from Intel Denoiser (which was delivering more details) to NVidia Denoiser with the "Reduce Flickering" option On. It didn't come near to solve the problem, unfortunately.
• I'm currently testing a scene with just the sunlight, and the flickering is really strong.

The solutions I found: I found two ways to solve almost completely the flickering problem

1. Increase a lot the samples on the render setup (from 50 to 250) and increase the FPS from 30 to 60. The problem is that the render time went to the sky, with more than 4 hours to render a 6s animation in full HD, and there was still a little bit of flickering.
2. Workaround: using a video editor, copy and paste the video layer, move the copy (upper layer) one frame, and change its opacity to 50%. This workaround allowed me to render the animation in about 45 minutes and get basically the same result I got increasing the samples and the FPS on Vantage.

Click here to see the result with DOF on, 60fps and 250 samples


But still, I think it would be great to have a way to solve that without needing to increase the samples so much, so we can create animations with DOF (which I personally love) without taking a day to render a 1-minute animation, for example.

[visualtracing__]

hi gabriel_chahouddealmeida ,

can you post the Vantage rendering setting?
I use 600 samples to get a clean result

[gabriel_chahouddealmeida]

Hi visualtracing__,

If I increase the samples to 600, the estimated rendering time goes up to about 09 hours.

Here is the screenshot of the settings I used for getting this result in about 04 hours (which I still consider too much):

[visualtracing__]

I was asking you about the render settings in advanced.
On the advice of the developers, I keep the "Only final pass" option deactivated and I must say that it seems much better.

[gabriel_chahouddealmeida]

I tried with the option "Only final pass" option deactivated, but it didn't make much difference on the result.

Here are the settings:

[visualtracing__]

I also use them like this, but I set the sample limit to 2000

[gabriel_chahouddealmeida]

You mean the LC sample limit?

[visualtracing__]

actually no! Shading graph for Glossy/GI on ON
why do you keep it off? you get a not so realistic result this way

[visualtracing__]

You mean the LC sample limit?

yes, sorry

[npg]

I noticed that the first video you posted looked familiar and I found the sample scene you used. I was able to roughly reproduce the view angle and tried some renders.

The "only final pass" option does not make a difference here (yes, there was a bug or two with this option in the past, but it seems to work fine now and it saves you render time). Hiding the window behind the chair also didn't help. The flickering is there both with the temporal NVIDIA denoiser and the non-temporal Intel denoiser. It's stable without the DoF. The combination of tiny reflection highlights from the tree leaves and DoF creates nasty noise (you can see it when you render with no denoiser and set the background to black). It looks like it just needs more samples to clean it up, I don't see another way around it...

[gabriel_chahouddealmeida]

npg Thanks for the feedback!

Then, my question is: to get an animation like this totally clean, without any flickering (or nearly that), I need about 400 to 600 samples. With those settings, the estimated render time is something around 7h for a 6 seconds animation, using an RTX 3060. Do you guys think that's reasonable or do you see it as a problem to be solved?

[visualtracing__]

It seems reasonable to me. It's about 3 minutes for frame. (full hd 25fps)
also take into consideration the card you have. with a 4090 perhaps you would halve the time.

3d mark perfomance rtx 3060 : 8739
3d mark perfomance rtx 4090 : 35966

[gabriel_chahouddealmeida]

visualtracing__ Yes, I understand that. At the same time, I myself don't see 3h ~4h hours for a 6s animation in Full HD (not 4k) with an RTX 4090 an optimum rendertime.

Important to remember that in the example I bring, the animation isn't even completely flickering-free, it's more like 80% clean. It would take even longer if I wanted to clean it completely on Vantage.

That's why I asked npg if Chaos sees that kind of render time as ok or as a problem to be solved. Personally, I'm going to use DOF a looot in my animations, so I'm a little bit worried.