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I am getting strange color noise in my diffuse direct passes. It shows up at the edges of the model, and at material boundaries on the model. It happens even with basic shaders (just diffuse mixed with gloss) but does not happen when diffuse and gloss are both gray, even with different values (or maybe it happens but just isn't visible.)

enter image description here

I have never encountered this issue before, so I am very perplexed.

Debugging so far: Does not seem to have anything to do with lights or edge settings. Happens with both normal and toon shaders. Only appears in diffuse direct, not glossy direct (or just isn't visible.) Is not visible in the combined pass, but makes problems when working with Diffuse Direct in the compositor.

My main guess is that it has something to do with a render setting in Cycles. Anyone else run into this?

Other render settings:

  • Happens regardless of resolution
  • Samples: 2,000
  • Clamp: Happens regardless of clamp value
  • Pattern: Happens with both Sobol and Multi-Jitter
  • Shadows, Reflective Caustics, and Refractive Caustics are all on
  • Filter Glossy: 1.0
  • Bounces: 5 max/3 min, Diffuse 4, Glossy 4, Transmission 12, Volume 0
  • Film: Exposure 1, Transparent, Blackman-Harris, Width 1.5
  • Post Processing: Compositing and Sequence on, Dither 0.00
  • Turning down the Width for Filter type under Film reduces but does not eliminate the problem.
Duarte Farrajota Ramos
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Ascalon
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  • Upload a blend file so that we can experiment on it. – 10 Replies Dec 15 '16 at 02:26
  • @10Replies I can't upload the blend as it involves work for a client (also why picture here is so small.) I will try to replicate problem in a fresh file. – Ascalon Dec 15 '16 at 02:27
  • Can you provide more info like system specs and render settings (CPU, GPU, AMD, CUDA)? Also better screenshots of material/pass settings would help. – Duarte Farrajota Ramos Dec 15 '16 at 02:28
  • @DuarteFarrajotaRamos I am using a Titan GTX on Windows 7 and Intel Processor, but this shouldn't have anything to do with it because a) it doesn't happen in other projects and b) it only happens in certain circumstances here. I'm adding overall render settings to the original question. – Ascalon Dec 15 '16 at 02:34
  • Then you better narrow down those 'circumstances' or provide more details otherwise it's impossible to diagnose with this little info – Duarte Farrajota Ramos Dec 15 '16 at 02:36
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    Diffuse direct is not meant to be used by itself, it is always supposed to be multiplied by diffuse color before being used to affect other types of lighting. Does the issue persist if you multiply the pass by diffuse color? – JtheNinja Dec 15 '16 at 03:46
  • @JtheNinja the problem does go away once I multiply by color. However, there are things I want to do in the shadows that this is interfering with. And regardless of what is intended for the passes, this is not normal behavior. – Ascalon Dec 15 '16 at 03:52
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    What exactly are you trying to do? By that I mean, please edit your question with an explanation of what you're attempting to do in the compositor, what result you're getting, and preferably a screenshot of your node setup. – JtheNinja Dec 15 '16 at 04:30
  • @JtheNinja I am doing some RGB curves, texture mixing, and displace on only the shadows. None of this is particularly relevant to the question as the problem exists in the base pass, it is not be caused by my node setup. – Ascalon Dec 15 '16 at 04:41
  • See: https://developer.blender.org/T48147 The problem is most likely in your composite setup (such as an operation not being applied to diffuse color, or diffuse color being multiplied in at the wrong point). Without a node setup, we can't help you with where. – JtheNinja Dec 15 '16 at 05:26
  • This behaviour is correct and necessary, since the color pass will get premultiplied later. See linked question for how to composite the color, direct and indirect http://blender.stackexchange.com/questions/64319/firefly-halo-on-glossy-pass/64322#64322 – Leander Dec 15 '16 at 06:46
  • @Leander Thank you. Do you want to put this as an answer? – Ascalon Dec 15 '16 at 07:05
  • Glad it helped. The question should be marked as a duplicate. (No extra answer.) – Leander Dec 15 '16 at 07:11

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