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After decimating my model I end up with many long triangle faces all sharing a vertex:

enter image description here

When rendering, these regions show up with strange artifacts:

enter image description here

If I set shade flat for this model, the artifacts go away, but I would rather keep shade smooth on as overall it makes the model look better. Is there an easy fix for this? I am running a rendering pipeline on many models so a quick fix (or even a hack) without much computation required would be great.

Blender file showing the problem:

jminardi
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  • Have you activated the Auto Smooth option? If it still doesn't work please share your file – moonboots Mar 20 '22 at 11:52
  • @moonboots Auto Smooth wasn't able to solve my problem without dropping the angle so low as to essentially turn off shade smooth for the whole model. I have updated the original question with a link to download the blend file – jminardi Mar 20 '22 at 13:16

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As Auto Smooth has not fixed your problem and working the topology would be a bit tedious, what you could do is give your object a Weighted Normal modifier, it will make Blender only try to smooth the small faces, not the big one, and your artefacts will disappear. Nota Bene: the Weighted Normal modifier needs the Auto Smooth to be activated.

enter image description here

A completely different solution would be to fake the 3 relief with a normal or height map.

moonboots
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  • Thanks! This seems to solve my problem perfectly. I can't fake the relief because these models are destined for 3D printing and casting so the geometry needs to really be there. – jminardi Mar 20 '22 at 13:34
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    ok but changing the shading will only improve the rendering, 3D printing is another story... – moonboots Mar 20 '22 at 13:36
  • The angles between the faces are tiny so they do not affect the casting at all, especially since everything is hand polished after casting. – jminardi Mar 20 '22 at 22:53