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Hi – I’m having problems with flickering in my scene when I render the animation (there's two renders in the video I linked to, the first with no BG light and the second with plenty). I’m going for a dark aesthetic, lit with lamps (area lights - the lamp you see), a point light (in the rear), and now some general background colour to lighten it.

(Above two first frames of the animation)

(Above first 4 seconds as GIF)

I started with just the lamps and a bit of back lighting, but noticed a lot of flickering noise in the shadows when I rendered so progressively added more light (see below). Things I’ve tried so far:

  • rendering with more samples. This helped slightly, but it’s a long animation so I can’t go too high; I got to 500 samples, but still saw significant flickering.
  • increasing max light bounces (didn’t seem to have an effect).
  • lowering Post Processing > Dither to 0 (seemed like something that could help; no effect)
  • checked Denoise seed is not animated
  • changing Denoisers – I’ve tried Optix and OpenImage, as well as reducing Clamping Strength to 0

Finally, after reading a bit, I realised the scene was much too dark, so I started adding fill light to the background. In the second render I have the background colour set to white and the Strength to 2, and it’s still flickering in the shadows – less, but it’s still there.

This isn’t an isolated thing, either – if you look at the texture of the dominoes here (which are static textures), it flickers quite a bit. Same with any glass texture I render as an animation.

My guess is it’s the denoising, but I’ve no idea what to change to make this better.

I’m using E-Cycles 3.3.0 with Cycles, but have rendered mostly in standard Blender to make sure it’s not an E-Cycles thing.

Should I try rendering the animation out and denoising it in other software? Does anyone else have this problem with dark-ish scenes, and if so have you found a solution? Should I go much lighter and darken it in post?

Many thanks for any help you can give.

Andy

Markus von Broady
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Andy
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  • have you tried decreasing the maximum bounce? Usually a clean render is a combo of good lighting, tons of samples, and a good composite. – ruckus Oct 13 '22 at 13:41
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    Hello and welcome. While files, images, and external videos or links may be helpful additions they should not be the only way to obtain information about your issue. Don't make understanding your question rely on downloading a file, watching a video or visiting an external site. Use the builtin tools to upload images or gifs, along with thoroughly explaining the problem in written form so it can be indexed and searched for thus helping future visitors with similar issues. – Duarte Farrajota Ramos Oct 13 '22 at 18:47
  • Hi @ruckus - just decreased the max bounces (by half) and no discernible effect. Do you know of any guides I could look up for this issue (rendering somewhat dark scenes)? – Andy Oct 14 '22 at 14:19
  • Hello @Duarte - thanks for the comment. Correct me if I'm wrong, but I don't see any way to upload gifs directly when writing a post, and I couldn't see any reference to this in the link you gave. Is there an easier way than linking to YouTube? Since I'm referencing output (my renders), a screen recording doesn't seem the most logical. – Andy Oct 14 '22 at 14:23
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    See How to upload an image to a post? or GIF There is a post specifically about authoring GIFs for Stack exchange. Videos are generally frowned upon here for various reasons including but not limited to being an external service that may be erased or lost, bandwidth, time it takes to watch, not being indexable or searchable, thus not helping future users with similar issues – Duarte Farrajota Ramos Oct 14 '22 at 15:44
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    When testing your animation output, first render the animation as PNG files, assemble them together in a video editing tool (e.g. Blender...) And play it in that tool - if the flickering is not there, it means the flickering is caused by the video encoder (the keyframes refresh the screen with more accurate data than one obtained by changes in non-keyframe frames, and this accurate data may be brighter or darker than the approximation). – Markus von Broady Oct 15 '22 at 08:36
  • Thanks @DuarteFarrajotaRamos - I understand the reasoning to keep media on BSE, and will do so whenever possible in the future. In this specific use case, however, it doesn't make sense to me - I'm trying to show details in a final render, not a process video, so reducing it to less than 2mb would likely destroy the quality needed to show this. – Andy Oct 15 '22 at 08:46
  • Hi @MarkusvonBroady, thanks for the reply. The video I linked to was rendered as a png sequence in Blender then imported to After Effects (still flickering) and exported vie Media Encoder (still flickering in final output), so I'm fairly sure it's not an artefact in one part of the process. – Andy Oct 15 '22 at 08:50
  • I think your problem comes down to: low samples + camera movement + denoising. Either due to camera movement the temporal reuse of samples doesn't work and so colors differ (with more samples the color averages would converge) and/or the denoiser has a different input, so also the output is not deterministic and it is as if you animated seed... – Markus von Broady Oct 15 '22 at 14:13
  • @Andy sorry you're having such trouble! Here is an external resource that I think could help you. – ruckus Oct 15 '22 at 19:13
  • Hi @MarkusvonBroady - appreciate the tips, but I'm afraid I don't know how to change either of those. Camera movement - I guess the fix would be to stop the camera moving? Which wouldn't really work for me. And I haven't changed anything to do with the denoising input (would also be strange, as this has occurred across several versions of Blender / E-Cycles, with default settings after reinstall). How can I check this? Many thanks for the help! – Andy Oct 16 '22 at 16:07
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    Thanks @ruckus - I think if I'm going to buy some external software for this it would be DaVinci Resolve, as I hear the denoising is pretty spot on. Thanks! – Andy Oct 16 '22 at 16:08

1 Answers1

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I had the same issue. Its caused by default denoising in Blender, that's done Frame by Frame so in an animation you will always see some "artifacts" between frames.

The best solution I've found was a step by step process inside blender that I found in a forum (https://devtalk.blender.org/t/taking-a-look-at-optix-7-3-temporal-denoising-for-cycles/18656/103)

The steps are:

  1. Change Output File Format to OpenEXR MultiLayer
  2. Check the Combined, Denoising Data, and Vector pass in the render layer settings and deactivate denoising
  3. Render the animation
  4. Ensure the OptiX Denoiser is selected in Blender Cycles settings and run bpy.ops.cycles.denoise_animation() in the Python console (And wait as Blender will freeze while it denoises the animation)
  5. Done (the EXR images now contain the denoised image sequence)

This workaround worked for me, hope it will work for you!

quellenform
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BlackBamba
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