Subsurf overlap

Can someone please tell me how to get around this problem…

Nautrally that’s a rectangular hole, the oval overlap is the issue.

Short of putting a loop cut either side of each line so i essentially end up with 3 vertices at the same point on each corner I can’t see a way of doing it. That doesn’t seem like a very tidy way to do it.

I’m sure it’s something simple :wink:

just add 1 or 2 loop around it


you can also do edge crease (shift+e) to mark the edges around the hole and the 4 going outwards in the corners as sharp edges. That way you don’t add any geometry

Thanks, I tried creasing and it definitely solved the oval hole problem but introduced another…

can you post the file? it’s difficult to tell what’s going on from these images only

No problem…

Thanks :slight_smile:

In the meantime I tried starting again, set everything up so there was a hole in the right place and selected everything, set smooth. I then selected the edge around the hole and set to flat, no subsurf at all. When I selected ‘rendered’ view the program crashes :frowning:

I’ve found a few tutorials on the subject of cutting holes in a mesh but none cover a rectangular hole in a flat plane whilst using subsurf. A lot of the other promising links I’ve found result in 404s. :frowning:

try to add an edge split modifier

it could be that some of the verts are not all at the same level !

so try to select these verts and do a scale Z to align all these on Z axis !


Thanks Ricky,

I’ve just tried doing everything (loop cuts, deleting face, etc) whilst it was a 2d plane lying flat and then extruded up and rotated the whole top face and the result in the same. It seems this is something people have had trouble with for a long time (making a square/rectangular hole in a subsurfed mesh)

This is one of those simple things that trips me up for a day or two :wink:

Kind of a front panel? If i’m right, then why not put some loops to hold it? Yes, it’s more vertices, ok, take that, no way around this time. No pain and smooth, precise…

Hi Eppo :slight_smile:

Yep. I’m willing to try anything if it works!

Are those edges from the corners what make it work? If so how did you get there? I did try to draw it myself but I blender doesn’t like the way I draw things :wink:

What do I need to do after this point?

can you show the model you want to do ?

and may be uplaod the file so we can look at it !


There is no model to post, I’m making a synth module (eg no keyboard) which is a pressed piece of metal in an upsidedown U shape.

So essentially this is the side view:-
l______l with rounded corners (and the other way up)

It also has a screen in the top right corner. The 90degree angles should have a smooth radius and the screen window should be sharp and rectngular.

Hope that helps :slight_smile:

(looking at the blend file above should make things clearer)

well i tryied to render the file you uploaded

and for em it looksok
no surface deforrmation

so you need to make the hole edges rounded

remove the creases and
just add some loop around the edges and it should do it i guess

unless you want something else


One would be your first - select face, extrude, scale, delete face. Got that oval… grrr… Ctrl-r from 4 sides, slide each close to corner - no oval.
Another was in thread you found - only left drawing: simply delete face, no extrusions. Then again Ctrl-R from 4 sides….blend

Thanks, after some more experimentation I found that shade smooth was causing the artifacts in the above image, I don’t know why.
I managed to get rid of the crashes by reinstalling blender, which is strange, maybe something corrupted?

I found that extruding the hole, like you said eppo, made a big difference. That, combined with a hard crease got rid of the overlaps.

This is what I ended up with…

are you sure all your normals are fine? black spots are often caused from normal interpolation if one is pointing one way and the next one the other, in doubt just recalculate them (select all, ctrl+n)