I am very new to blender and I am working on some projects to help myself become more acquainted with the program. I am currently working on a mask:

Revan Mask Front View Revan Mask Angled

Thats the material view and looks fantastic to me. But then I go to the rendered view and this happens:

Revan Render Front Revan Render Angled

If anyone can help me solve this issue it would be very much appreciated. And here is the file:

  • $\begingroup$ plz attach file here blend-exchange.giantcowfilms.com $\endgroup$ – atek Oct 24 '17 at 4:27
  • $\begingroup$ well i did not get the question But then I go to the rendered view and this happens: Means?? what u need $\endgroup$ – atek Oct 24 '17 at 5:31
  • $\begingroup$ @atek compared to the material view I posted in the first two pictures, the render has lines that should not be there and the mask seems to be extending out at the top of the cheek $\endgroup$ – G. Worth Oct 24 '17 at 5:35
  • $\begingroup$ In the tool shelf Add smooth shading. And in the modifier add edge split modifier $\endgroup$ – atek Oct 24 '17 at 5:40
  • $\begingroup$ @atek Thank you very much that worked great! $\endgroup$ – G. Worth Oct 24 '17 at 5:58

Apart from flat shading (instead of smoothing, as pointed out by @atek) your mesh has a few other issues: apart some ngons, which are considered bad topology, but it could work for your needs, there are a few nonplanar faces (mostly ngons), and those are causing artifacts, as visible below.

The good news is that you can find solutions to them all using the bundled 3d print addon (you just need to activate it in user preferences), as shown below:

enter image description here

First, I forgot to say that before using the 3d print toolbox "check all" tool, I already recalculated normals (Ctrl+N).


  1. What you should have done is: try to not use ngons (ie: faces with more than 4 vertices) and if possible also avoid triangles. Why? Because this easily create problems, gives artifacts in 3d viewport and rendering, and behaves horribly if you need to animate deforming objects. The additional lines that have appeared in the render are the ngons being split into triangles as ngons themselves are not renderable.

It doesn't seem to be the case with this model but, since you're learning, it would immensely help you if you try to model everything with "quads" or, if really needed, "tris". Note that even "quads" could be made (by mistake) non planar, but while it is less likely, they will be much more easy to fix.

  1. What can you do now, to improve this model? This is a difficult answer. In a few words, you need to convert those "ngons" into "quads". This goes under the name of "retolopogy", ie: create a new (better, simpler) mesh structure for a shape that already exists.

I'm not a retopology genius, and without reference images it's even harder, but I tried to "fix" a small portion of the mask, by deleting faces (only faces) and subdividing remaining edges to make them nearly match their "quad" counterparts, sometimes "sliding" vertices along an edge, and rebuilding faces based only on 4 vertices.

Now, shown below, you see that after pressing "check all" again it doesn't identify those areas as issues anymore:

enter image description here

  • $\begingroup$ Your answer doesn't really explain what the user is meant to do once they've found the n-gons/non-planar faces. $\endgroup$ – Ray Mairlot Oct 24 '17 at 9:25
  • $\begingroup$ @RayMairlot you're right, but I was in doubt: the question is about "strange lines" due, apparently, just to flat shading... what I show above is probably a totally different topic which probably needs another question like "how do I fix non planar faces in my model?" I just pointed out those errors in the mesh... I could add some resolution path, but I'm not sure it belongs here... $\endgroup$ – m.ardito Oct 24 '17 at 9:30
  • $\begingroup$ The issue is caused by the n-gons being unpredictably split at render time. The smooth shading and edge split modifier are just a workaround. Your answer gets to the root of the problem (or it will if you explain what the fix is). $\endgroup$ – Ray Mairlot Oct 24 '17 at 9:39
  • $\begingroup$ @RayMairlot I've added some more content to the answer, I hope it could be considered enough for this context. Anyway he already accepted the other answer, so maybe he's no more interested :D Imho he should add another question about fixing this mask model, and get more and better focused advices there... $\endgroup$ – m.ardito Oct 24 '17 at 10:25
  • 1
    $\begingroup$ Don't worry about accepting my answer (btw, on this site it is perfectly fine to switch to another later answer if you wish: it's your question, you choose) I'm not that much after rep points ;-) I can see the background image set, but (any) images are never saved inside .blend files, unless you explicitly "pack" them (there's a command to do that, search this site or blender manual). You can model how you wish, but if you use quads only, and sometimes is not easy, you'll thank yourself later: it's always better. $\endgroup$ – m.ardito Oct 24 '17 at 17:44

Switch to Edit Mode -> Flip Normal

In Object Mode -> Tool shelf -> Shading -> Smooth

In Modifier tab Add -> Edge Split Modifier

enter image description here

  • 3
    $\begingroup$ Good, but I added another answer to show some topology problem, I think he'll learn better to fix those, instead of relying on edge split modifier to make it just look better. Its' good, and non destructive, but it leaves bad topology, even applied. $\endgroup$ – m.ardito Oct 24 '17 at 6:55

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