Subd to NURBS Error & Surface Packing


I’ve been working on a project that involves converting Subd to NURBS with surface packing enabled. There are right around 37,000 subd faces in this object. I’ve been recieving several errors like the one in the image below and almost none of the surface patches are packed.

Has anyone else encountered this issues? Are there any solutions to this?

moved to SubD category

Hi Benjamin -
Please post the 3dm file with the original SubD object.

Hello Wim.
I will talk to my tech leads first thing on Monday morning. The model data is confidential. I know we have an NDA in place with McNeel, I just have to go through the appropriate channels on my end before sending any math to an outside party.


To be confirmed when we look at the files, but it is likely to be this bug: RH-62751 ToNURBS: SubD with 450k faces fails to convert to NURBS, missing faces around extraordinary vertices

It’s been reported a few times, the bug is not triggered when the SubD has fewer than about 32000 faces. Does the SubD come from a QuadRemesh? Would you lose a lot of details by reducing the face count target to 30k or so?

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Yes, in this instance it was from a quad-remesh. It’s also happened several time using sub-d “toNurbs”. It’s not common in most cases but tends to happen with higher face-count models.

I’ve spoken to some people here in vendor and supplier relations for Design Center so the wheels are in motion. It’s going to take a few days on my end, but once the roles are cleared I will he in touch via email. I’ll have to send you the file via P2P. We use Aspera so I’ll send you guys the set-up info.

I’ve solved the issue with a work around but I would like the send the info anyway. Thanks for the response.

RH-62751 is fixed in Rhino 7 Service Release 20