Sweep2rails conversion to subD - Rhino 7

Dear all,
I am using Rhinocerosos 7 Beta.

I need to create surfaces based on sweep 2 rails and transform them into Sub D.
In correspondence with the parts where the tracks are curved the subDs show an incorrect trend, there is an inconsistent duplication of vertices.
I tried to use ARCO, SPLINE type curves and also to convert the two types to SUBD FRIENDLY CURVES.
The result after converting surfaces to SubD is always incorrect, with a lot og jagged part!

Is it a software problem?
Do you know if I can improve my results in someway?

Attached you will find a document in which you can see step by step my tests and results.

Thank you in advance for the help.

Apparently your document attachment didn’t succeed. I see no link in your post.


I try again.
problem_sweep2railsTOsubD.pdf (732.9 KB)

Can you see it now?

Thanks in advance for any help.

Hi Laura -

Please post a 3dm file.
Also, why do you want to convert to SubD and not just create SubD objects directly from the input curves?

I need to model the surface becuse I’m testing for research poupose a working pipeline based on step curve>surface>subD, using script.

Here the 3dm file:
test_02.3dm (1.1 MB)



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How do you obtain this good result?
Did you started from the last surface model of the first line (joined binary based on line + control point curve subD friendly)?

Many thanks for your help.


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Dear Inju,
thanks a lot for your suggestion.

Unfortunatly, I woud like to skip the step through the ‘quadremesh’ function.
My aim is to get a subD with a very low net polygon count.
For this reason I’m tring to use only the ‘Converto to SubD’ tool.


SubDSweep2 is new Rhino 7 command. This command sweeps a shape curve along two rail curves to create a SubD.

:slight_smile: thanks

I’d say your sub-d friendly curve wasn’t sub-d friendly yet. I moved the section curve in the middle down to the control point and got this sub-d with the SubDSweep2 command:

test_02.3dm (59.3 KB)

thanks for your suggestion.

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