So I've created an X and I used a mirror to make the right side of the X and have it symmetrical to the left side. As shown in the picture: The X

The problem I am having is when the image is rendered it looks like this: Rendered X

At the axis of symmetry for the X there is a weird black line? I think it's due to two lines meeting at the same points? I don't know how to fix this and I would really appreciate any help. This is my first time using blender ._.

  • 1
    $\begingroup$ Have you checked the merge option in the modifier panel ? $\endgroup$
    – Aleph
    Nov 3, 2015 at 22:27
  • $\begingroup$ @Aleph Yes that option is checked. i.imgur.com/B8D8ZHG.png $\endgroup$
    – user19249
    Nov 3, 2015 at 22:33
  • $\begingroup$ And why not applying the modifier and 'w'-> 'removed all doubles'? Unless you want to have the possibility of a further modification... $\endgroup$
    – Aleph
    Nov 3, 2015 at 22:38
  • $\begingroup$ @Aleph What does "remove all doubles" do? $\endgroup$
    – user19249
    Nov 3, 2015 at 22:41
  • 2
    $\begingroup$ I think it's not necessary to apply mirror modifier in order to get rid of artifacts. First check whether these vertices (located on the mirror plane) are co-planar or select them and scale by Y axis to 0. Second, check whether there are internal faces. $\endgroup$
    – Mr Zak
    Nov 3, 2015 at 22:51

1 Answer 1


Actually, this can be many things:

  • First try to change the merge limit value, and have a render.

If it doesn't work :

  • in Edit mode, while zooming at maximum, make the twins vertices (of the top of your object, for example) -one for each side or your mirrored object - the closest as possible, overlapping themselves. Try a Render, it should solve the pb.

If not :

  • if you don't plan to have further modification on your shape, once it's finished, in Edit mode, you can apply the mirror modifier, then press A (it will select all the vertices), then W, then remove doubles, it will merge the overlapped vertices And try a render :)
  • $\begingroup$ thanks for the assistance :D this worked perfectly, I changed the merge limit until the vertices merged. (and remove doubles sounds like it will be useful in the future :P ) $\endgroup$
    – user19249
    Nov 3, 2015 at 22:57

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