2
$\begingroup$

I'm currently working on a scene, where I'm making some basic models (I have very basic modelling skills), and have a mesh made from a cylinder, that after making a few edits to, and applying a bevel + subdivision modifier to, results in this weird geometry:

Smudged corners

I was able to drastically reduce that, by adding a loop cut, and increasing the subdivision level:

enter image description here

..but still wondering, what causes that kind of topology? Is it a common issue, that needs to be resolved with loop cuts or am I missing something?

Thanks in advance for whoever reads/replies to this 🙂

Edit #1

Tried the alternative technique suggested by moonboots, which works in keeping the corner sharp with the subdiv modifier, but also results in this weird topology:

enter image description here enter image description here

Edit #2

I must have selected an extra diagonal edge in the previous attempt that created the ngon, but even after select the right edges (I think) I now get the following smoothing:

enter image description here enter image description here

Improve this question
$\endgroup$

2 Answers 2

Reset to default
3
$\begingroup$

Because of your topology, the Subdivision Surface tries to round this corner:

enter image description here

If you choose this topology instead it will work fine:

enter image description here

Edit: As I said, you need to avoid ngons on round surfaces because it tends to create artefacts, instead stick to this kind of topology:

enter image description here

The problem with the topology that you show below is that there are still these 2 faces and the Subdivision Surface modifier tends to round the shape, therefore the artefacts:

enter image description here

See the difference between these two topologies, you need to choose the one on the right, it will be easier to rework and sharpen when you'll give it the Subdivision Surface modifier:

enter image description here

Improve this answer
$\endgroup$
9
  • $\begingroup$ Thank you for taking time to reply and demo this to me. I've tried manually subdividing the outer and inner edges of the inset like in your screenshot, and it works! Though around that corner, there's a bit of a weird bump happening, which I assume is due to the resulting topology (see edit #1 in post). Is there a fix for that too? $\endgroup$
    – Abraham S.
    Apr 15, 2022 at 10:01
  • $\begingroup$ could you please show a picture of the problem or even share your file? pasteall.org/blend $\endgroup$
    – moonboots
    Apr 15, 2022 at 10:02
  • $\begingroup$ Apologies, was still uploading it, it should now be on the post. $\endgroup$
    – Abraham S.
    Apr 15, 2022 at 10:04
  • $\begingroup$ there's a ngon in your topology, which tends to create artefacts, try to stick to the topology I propose $\endgroup$
    – moonboots
    Apr 15, 2022 at 10:08
  • $\begingroup$ I must have selected an extra edge to many, but now reselected and bevelled the correct edges, and now have the original issue (see 'Edit #2'). Am I doing something wrong? $\endgroup$
    – Abraham S.
    Apr 15, 2022 at 10:18
3
$\begingroup$

In addition to what others have said, A good rule of thumb when modeling in subdiv like this is to make sure you have plenty of geo to start with as well. You don't want to be going from a 16 sided cylinder to a 256 sided cylinder in one jump. Try to apply some subdiv modifiers in stages, or at the very least start from a place that is closer to your final result. Big shading distortions and lines on the side of cylinders is a sign that you are asking the subdiv modifier too much.

For example, this cylinder has literally no "special" edge-loops or crazy pro-level geo applied; it's literally just a cylinder with an inset. But since I'm only asking the subdiv modifier to smooth out the final result instead of do half my modeling for me, The result looks a million times better without even trying.

No subdiv Applied: enter image description here

With Subdiv Applied: enter image description here

Improve this answer
$\endgroup$
2
  • 1
    $\begingroup$ his topology is a bit different as there's a kind of inset for his window but yes I would have avoid this inset $\endgroup$
    – moonboots
    Apr 15, 2022 at 11:02
  • $\begingroup$ Thanks for chiming in! I've tried your topology (so without the inset face that creates the diagonal edge) and I still get the artefact on the corners from the subdiv modifier. $\endgroup$
    – Abraham S.
    Apr 15, 2022 at 11:19

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .