SubD Aligning/Collapsing Edges


I was just wondering if there was a way to align the edges of a SubD to make them all horizontal / vertical where possible, and perhaps even collapse small edges between two vertices. In the image attached for example, I managed to do that with the top band but am struggling to do that with the bottom band. Being able to collapse / align vertices will definitely help with cleaner modelling, but might also help with bridging issues of unequal number of edges (to name a few)?



Hi inju,

Thanks very much for the example - I’ve tried using _Align already (exampled from another thread I can’t find anymore for some reason) but it didn’t work. Stitching the vertices successfully collapsed the points. However the seam remains curved / not aligned. *Updated image attached.

I wonder if there’s a way to split a SubD face with more control? _InsertEdge is handy but lacks that control - perhaps a way to _SplitFace and draw a line across it to control the seam / split location?


Not a quality topology.
The screen for full information is not enough, you need a file.

_InsertPoint command.

Hi, sorry - I have attached the main geometry in question. I had to remove parts of the model, but the main part is in there (I think the topology isn’t that bad?) and the curves I’m trying to align on a separate layer. Please also let me know if you think this does not actually make any difference. I’ve noticed that converting to NURBS can have varied effects & I don’t fully understand the mechanics of it all.

_InsertPoint definitely works well thanks for that! I’m still wondering if there’s a way to set that crease / segment to be flat (kind of like SetPt > Z with a curve for example).

200815_SubDEdgeProblem.3dm (121.6 KB)

Topology is dirty.
You should learn the basics of SubD topology.

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Thanks for that Inju. Are you able to perhaps point me in the direction of some basics of SubD topology resources to learn from, or what specifically was wrong with that topology that made it dirty?

For example, I’ve taken a look at some of these resources from McNeel among some others to try & understand SubD further:

I managed to tidy up that model (please do take a look) taking prompts from your video snippet and I think it’s looking much better! I’m just curious if there’s a primer of sorts that might maybe explain why the subdivision is the way it is / why we can’t hard force edges / vertices to align?

200815a_SubDEdgeProblem.3dm (105.1 KB)


Hi @inju
That looks like a great read - I’ll be sure to get it!
Thanks :slight_smile:

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Thanks very much @inju! :slight_smile:

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Thank you so much Inju~ :slightly_smiling_face:

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you can also use gumball to align stuff… relocate it to where you want stuff aligned, and then scale to zero using one of the 1d handles.

works on meshes, and curve points as well-

( I have a hot key for reloacting gumball)


Just to add to what Kyle mentioned… you can also click and drag the center of the GB with Ctrl or Cmd held to relocate the origin, change the angle of a rotation handle, position of a translation handle or length of a scale handle. This is how I personally relocate the GB when flattening selections. Note you can click and release the scale handle and type 0 like Kyle said but they also snap to the origin now when dragging them to do the same.