I've got an animation I've rendered that looks pretty good, with exception of a subtle flicker in the highlights.

Unfortunately I can't share an example as the work I'm doing is under an NDA but I'll try to explain it as detailed as possible.

I've got an interior setting, an airline cabin to be specific, and a camera panning through the rows of seats. Imagine walking down the aisle with the camera facing the wall and windows. I'm happy with the lighting, shadows, and so on, but frame to frame, there's a subtle variation in lighting among the highlights, mostly where the light streams in through the windows and on the glossy plastic surfaces. It's as if each frame has been calculated slightly differently. I at first thought it was a case of video compression, but I can see it even with no compression.

Most of the lighting is coming through the windows with an HDR outside, it is cranked up to 30 for the strength which gives me the look I'm going for. There are interior lights as well above each seat.

One unusual thing I'm doing is using the filmic log encoding base, it's a set of colour settings I've installed from here: https://sobotka.github.io/filmic-blender/

The result in my opinion is far superior contrast in my aviation renders given the nature of intense bright light coming through small windows.

I'm rendering in cycles, GPU, with 600 samples and a max noise threshold of 0.01. I've seen noise issues when I reduce this setting so I've left it pretty high.

Do I need to change other settings? These 200 frames take about 8 hours to render, so I haven't been willing to spend too much time experimenting.

  • $\begingroup$ Can you reproduce the error in a toy, open-source scene? I can see why, despite your extensive description, this has been flagged as 'unclear'.. it's just that there are so many variables.. Are you denoising? Does the flicker persist if you switch it off? $\endgroup$
    – Robin Betts
    Commented Aug 6, 2023 at 10:44
  • $\begingroup$ hmm, I started to read up/ watch videos on temporal denoising. It takes the lighting calculations of 3 frames and averages them out to reduce flickering. It looks a bit complicated but the example I saw in one video has similar flickering to what I was experiencing. I think I'll give this approach a try. I guess the weird thing to me is that this is the only scene I'm experiencing this with. $\endgroup$
    – AviRenders
    Commented Aug 6, 2023 at 19:18
  • 1
    $\begingroup$ on second thought, this sounds easy: blendernation.com/2022/01/10/… Will give it a try and see in a few hours if it works. $\endgroup$
    – AviRenders
    Commented Aug 6, 2023 at 19:33

1 Answer 1


I think I've got it solved, although it's not the easy solution I was hoping for. My passes, even at 600 were too low for the scene. Bumping them up to 1800 makes a difference. The flicker is incredibly subtle but something I can live with. That being said it took 5 minutes per frame to render.

The temporal denoising I posted earlier, didn't quite solve the issue unfortunately.


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