when I render with Cycles any mesh (specially planes) with a bit of irregular shape (by using previously, for example, a displacement map) some black lines appear on it. Those black lines are not random, they are always matching the edges of the geometry:

different representations of the same object


I tried switching between Smooth and Flat shading, changing material, but it does not affect. I have to subdivide it many times to get smaller lines visible, but that is not a solution. Those artifacts only appear in non-planar faces. You can see another example at this render:

enter image description here Notice the brick texture is completely covered in black lines. The 3D model it's a simple subdivided plane and a displacement modifier applied over it.

Any idea? It seems that when the angle between two faces reach some point the edge is rendered in black color. Did I forget something to avoid this annoying thing? Thank you in advance!

  • $\begingroup$ This may be just a numerical issue, related to this question and already reported as a bug. Scaling down your object might solve the problem. $\endgroup$ – quiliup Aug 14 '18 at 20:56
  • $\begingroup$ Great! scaling the objects that suffer this effect might mitigate or accentuate the artifacts. Instead of scaling my scene, I chose to translate all the objects to a position closer to the (0,0,0) coordinates and the issue dissapeared as well. Thank you very much quiliup, didn't know this was a bug. $\endgroup$ – Danidrac Aug 15 '18 at 11:59

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