Convert Degree 3 to SubD friendly?

Hi @dalelear , I need a little help here:
I am working on a SubD tool to make some quads from some curves, but the whole “curves” vs “SubD friendly curves” is not very user friendly for ongoing projects for us I am afraid.
(And “ToSubD” could benefit from a tolerance warning IMO, so a user doesn’t think that it was converted all right when it wasn’t.)

So back to topic:
How can I convert a Degree3 curve to a SubD friendly one?

I can’t find a tool, so are there any other logics I can use to make sure my subD fits within tolerance?

Not being able to combine SubD and normal Nurbs is a big problem, and remodeling everything to use SubD friendly stuff is a no go, so the subs needs to be Nurbs friendly for us :slight_smile:

I wish SubD used the same logic as Nurbs when it comes to controlpoints, but it is neither close to Degree 2 nor Degree 3, and we need to use curves that already exists, so how can I convert that? Is it a simple tool?

Thanks for any help!

Here is a file that showcases my problem:

  • I made curves that are SubD friendly
  • turned on controlpoints and traced with NORMAL degree 3 curves.
  • Then I extrude them and one becomes a nurbs and the other a subD.
  • until I try to convert the nurbs one to SubD.
    Then it doesn’t look identical any more:

On the right you see a subD that fits the curves perfectly, that’s what I am after only that the input should be unsubdfriendly, so I need to figure out how to convert it :slight_smile:
Is it possible?


SubD curve vs Nurbs extrude and convert.3dm (106.3 KB)

Hei Jørgen -

Just to answer that simple question with a simple answer:
Use elmo (a.k.a Rebuild) with the Make SubD friendly option ticked on.

1 Like

OK, but that isn’t automatic regarding tolerance and I see FIT doesn’t support SubD friendly yet.
Can you add a wish for that Please?

I need an explanation…?

Hei Jørgen -

On the list now: RH-58982.

Hi Jakob -

If you insist…
That was the original name of the command before it was renamed to be Rebuild.
I just never got used to not using elmo…



Was that an acronym or was it just a reference to, err, Elmo?

I Norbert -

I guess I should have posted a link this this post instead of that other one in the same thread:

But, no, it wasn’t an acronym.

Long live Elmo!