Artifacts on flat surfaces

Support Modeling
1

I’m dealing with artifacts on flat surfaces then and now and would like to find a workflow to get rid of them. It’s odd that they only appear in the final renderings but are not visible in the render previews. Unfortunately the options when filling a flat edge loop are rather limited and I can’t get a more “pretty” triangulation by using ALT-F. The surface is completely flat and I also made sure that the shading is set to “Flat” as well.

Here’s a comparison of the three views (click to expand the view).

Blender_Artifacts_01
Blender_Artifacts_01723×1644 175 KB

Any ideas?

2

Have you tried filling the edge loop with Control + F ➔ Grid Fill?

If that works (depends on the surrounding edge structure), you can change settings with F6 (Blender 2.7x) or F9 (Blender 2.8+).

You can also try adding an Edge Split modifier to the mesh after the fill.

1 Like
3

Hey.

Yeah - I tried the Grid Fill. But it causes issues in the concave areas where the mesh goes outside the edges. Adding the edge split modifier didn’t solve the issue either.

4

Hmm… :thinking:… Did you also try the Weighted Normal modifier?

Or if it’s purely an extrusion you can try the free Boundary Aligned Remesh add-on for an even triangular fill of your edge loop. Then extrude the result.

1 Like
5

Unfortunately there is no “Weighted Normal Modifier” in 2.79. But I will see if the addon helps. Cheers.

1 Like
6

The addon doesn’ really work too well. I can’t remesh the flat surface by itself but have to remesh the whole model which results in bad topology where it’s perfectly fine as it is.

7

:neutral_face: Then I’m out of advice, sorry. Hopefully an other Blenderhead can help you out.

Good luck!

1 Like
8

You’re probably more experienced than I am with Blender and 3D art, but I get similar problems when I accidentally get geometry that isn’t “connected”, leading to extra faces that are right on top of one another. Merging vertices doesn’t help in this case.

For example - the little line in this picture is because extra polys are trying to occupy that exact same spot.

capture1
capture13840×2160 535 KB

The best way to check is to just start grabbing edges and faces around the problem areas to see if they might be unneeded.

capture2
capture23840×2160 536 KB

1 Like
9

Cheers anyway. I’ve found a workaround by insetting the loop, circularizing it with LoopTools and then fill it. It’s unfortunate that it doesn’t “just work” although it looks fine in Preview.

1 Like
10

Hmmm. Not sure if we have the same issue here. It seems as if you already see your problem in Preview, while mine only appears in the final render. I’m also quite certain that it hasn’t anything to do with overlapping geometry.

11

I’ve exported the affected object to an OBJ file. You can try it for yourself if you have time.

Artifacts_Check_01.obj (416.2 KB)

12

I believe you. Plus, my obj importer is busted. Using Blender 2.80 (released/non-beta), I have the OBJ import-export add on enabled, yet I still see no mention of obj in my File > Import menu. In fact, anything I check for import-export in Preferences has no effect whatsoever. I don’t have a clue about what’s causing the problem.

I don’t want to hijack your thread though, so hopefully someone else will be able to suggest something that might be more appealing than your workaround. :slight_smile: Have a good rest-of-the-week.

1 Like
13

One more thing I can think of: did you perform a Non-Manifold check?

  1. Enter Edit Mode ➔ Vertex mode.
  2. Deselect all.
  3. As you are using Blender 2.79, press Control + Alt + Shift + M.
  4. There’s a slight chance there are double faces or other non-manifold elements that cause the artifacts during rendering.
  5. If there are issues, you can try activating the 3D Print Toolbox add-on and press the Make Manifold button.
1 Like
14

Here’s a test scene for Blender 2.81. Maybe this works.

Artifacts_Check_01.blend (1.2 MB)

15

Tried it. No Non-Manifold Vertices in there.

1 Like
16

It’s pretty strange to me. I’m not seeing any artifacts at all.

Untitled-1
Untitled-13840×2160 543 KB

Untitled-2
Untitled-23840×2160 513 KB

1 Like
17

Maybe shading has improved since the introduction of Blender 2.8.

1 Like
18

Please just load the file and hit render. It seems as if you rotated the object and changed the scene.

The camera angle should be like this.
image

19

This scene is for 2.81. The problem is there in 2.81 as well.

20

I don’t have 2.81 so I’m out-of-luck for exactly recreating the problem. Are you using it, @Metin_Seven?

1 Like