HELP! Weird random scattering in shadow

Support Lighting and Rendering
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Can anyone please please help me. I am having an issue with my render (attached) - everything looks perfectly fine, except when the back of the land satellite shows, there is a very odd light/shadow scattering going on and I can’t figure it out. (it is much more apparent than in this example because of the compression/size - to see it please view in full screen or zoom)

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Are you using a denoiser?

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I am with Cycles

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It looks like you have a main cause, but it is being hidden by something else. The main cause is that your sampling is not randomized per rendered frame. What this means is that there is a slight sampling bias that creates a barely visible pattern in a still frame, but when watching a bunch of frames in succession, the pattern is clearly visible. What I believe, though, is that you are using denoising as part of your render pipeline which takes those biased samples and smears them so they just look blotchy.

The fix is pretty easy. Just click the clock icon next to your sample seed and it will change each frame. Your denoiser will still make your samples blotchy, but they will at least be different blotches each frame and appear more random. Here is a screenshot:

Screen Shot 2020-08-13 at 4.27.17 PM
Screen Shot 2020-08-13 at 4.27.17 PM2885×1750 675 KB

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This is a known issue that all denoisers blender have can’t compare current frame with the next or the previous one. This leads to cases where a single frame looks good but when you play the animation use can see some flickering.

All you can do is increase the render samples so you rely less on the denoiser.

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Thank you! My samples are just around 300 so I thought it might be something else. Going to attempt higher and also tryout Hunkadoodles tip!

Thank you both! I’ll keep ya updated!

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is this maybe a terminator artifact problem? your object is pretty low poly so…