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When I got an unnecessary detail on my model that I dont need, (Like in the picture) I dissolve the faces of the unnecessary part and scale it by 0 at the (x/y/z) axis. It makes a perfect square. Does this operation create a huge ngon or not?

before

after

The triangulate modifier doesn't process it like a square, it also process the perfectly aligned vertices. However, that just can be how the triangulate modifier works and it can be a perfect quad anyway. triangulated

Is this an ngon, or is there another way to see the final triangulated mesh?

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    $\begingroup$ Second screenshot is a huge Ngon, quad on the third screenshot doesn't appear to have any reason since there is huge amount of tris around it. It all depends on the purpose of the mesh (further subdividing, beveling, exporting to game engine, etc). Ngon is a face with more than 4 verts; it can be planar (all verts on the same plane) or non-planar, which is even worse $\endgroup$ – Mr Zak Oct 13 '18 at 19:26
  • $\begingroup$ Thanks for the reply. I thought second could be a quad, vertices between main four vertices has nothing to do with inside, i cant see any reason preventing it from being triangulated as a normal quad. But it is usefull anyway(for subdividing,beveling. it works as expected). I added third screenshot to check if the quad is properly subdividing into 2 triangles, apperently not. $\endgroup$ – Mert Oct 13 '18 at 19:34
  • $\begingroup$ There's only one edge between two verts, it doesn't matter if it's only intersected "from the outside", that intersection is still a vertex, so your square is a 24-gon in this case, and not a quad, even though the inside edges have been removed. The vertex breaks the edge whether it's connected to anything or not. $\endgroup$ – A C Oct 13 '18 at 21:58
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When modelers refer to an ngon, they only mean non-quad faces, really.. some include tris, some don't.. The main reason to avoid them is that under Catmull-Clark subdivision they can generate pinch-points, and irregular normals. So yes, the square shape in your first example is an ngon. Very squashed quads, or quads with a concave pair of sides, don't subdivide well, either.

On a perfectly flat surface, with a convex perimeter, that's not going to deform, there's no need to panic about them. As the the subdivided cylinder in the illustration shows, the first generation of subdivision will generate quads anyway.

However, poles, that is, vertices where more than 4 edges meet, can also generate pinch-points. As before, if they are on a perfectly flat surface they aren't anything to worry about.. but if they threaten to interfere with a smooth curvature, or make holding loops (which sharpen edges between planes) or other edge loops hard to create or maintain, you should try to avoid them. In deforming surfaces, as far as possible, they should be maneuvered into non-deforming areas.

With those things in mind, If I wanted to finish my cylinder with an ngon, I would prefer to do it with a single inset (or bevel).. as shown on the left.

enter image description here

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i would rather to use grid fill option,it creates grid shape which fills the hole by new grid topology

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  • $\begingroup$ While this doesn't quite adress the questions content, it could be a very useful answer if you could go into "creating an ngon or not". Otherwise, short information snippets like this, should be a comment. $\endgroup$ – Leander Oct 14 '18 at 16:32

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