problems applying subsurf with mirror

I have a model that looks nice while using subsurf and mirror modifiers - until I try to apply the subsurf.
Then things go somewhat wrong along the seams (the mirror plane) - the seams between the actual and mirrored parts
of the models are starting to open up, as shown attached images, the curve splits up in the middle
(where the mirror plane is) , the original curve before the subsurf application is bellow.
Is there some way to prevent it ?
Thanks !


Make sure the mirror modifier is at the top of the stack. The mirror modifier must be applied first before the subsurf because the above will happen, hope that helps. :RocknRoll:

Also, something I do is tick the Clipping box in the Mirror modifier and make sure all of my center vertexes are really on center. Actually I make a habit ticking that box when I create the Mirror modifier and only turn it off when it interferes with modeling.

  • Bill

Thanks for the replies. I do indeed make sure the clipping is checked and the center vertexes are right on center, but I am still getting
the same split…
Regarding the order in which the modifiers should be applied - I would like to avoid applying the mirror first, because I actually want to
keep editing the object and add parts that have straight lines and corners, which is why I want to apply the subsurf first, because
I want these straight lines and corners to also be mirrored - so this is actually not possible I guess ?
is there any other way to apply subsurf to just parts of an object ?

Subdivision surface modifier is for the whole object. It can be before mirror in the stack but you have to make sure mirror modifier gets all the vertices to the mirror plane where it can merge them. It’s not recommended and is slower but there are ways to do it.
Either use subsurf in simple subdivision mode (no rounding), make sure it has continuous face loop all around where the mirror plane is, or use edge crease (shift+e, or on top of the properties panel). You might need to crease edges parallel to mirror plane axis in the corners for it to work.

It’s possible to do localized subdivisions with subdivide tool (W -> subdivide or subdivide smooth) but then you have topology issues to solve and you can’t remove them like you can with a modifier.