Need to work with hundreds of polysurfaces

Hi, I am experimenting with Rhino 5 (Windows 7 Evaluation) Probably asking a stupid question. I have a plan of a neighborhood as an autocad file. The individual buildings’ roof lines are drawn with 3D polylines and placed on correct elevation. Can’t extrude these on AutoCAD- at least not in the version I am working with. I was able to extrude them on Rhino, but they look like open tubes. I want to turn these lines into building blocks. Is there an easy way to do this operation on Rhino preferably globally if not individually? Thank you, Ron
forum.3dm (103.8 KB)

Use Extrude (planar curves) from the Solid menu

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Hi Ron - Your polylines are not planar and so it’s impossible to create closed polysurfaces from these without somehow pre-processing the input curves or post-processing the open tubes.
For hundreds such shapes, that quickly becomes impractical without some form of scripting.
The better way would be getting your hands on accurate input data - but FWIW, here’s a quick Grasshopper definition to, somewhat arbitrarily, create closed objects.

Roof Input Crvs Flattening and Extrusion - (11.4 KB)

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Thank you for your reply Helvetosaur. I’m afraid it looks exactly same as what I got via commandline ExtrudeCrv. Did you have the chance to review the file that I sent you? Appreciate the help!

Maybe this…? (1.5 KB)

Script to transform non-planar curves into planar cuves parallel to the world
XY plane and at the choice of maximum or minimum Z height,
Works best with “near planar” curves.


Except that, just by reading the description, that seems to flatten them parallel to the world XY plane.

I thought that is what was wanted…

The roofs appear to be pitched.

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Sorry if I wasn’t clear, indeed I would like to retain the slopes on the roof of the buildings, therefore flattening is not an option. I am trying to digest all this info. I installed the trial version (ver 5) can’t get the latest one work on my system (win 7).
After struggling with autocad and sketchup the Rhino seemed promising but now I am a bit lost. Wim DekeyserwimMcNeel…how can I apply the Grasshopper definition?
(I understand that it can be a bit frustrating to repeat the same things over and over again. Is there a tutorial for this? thanks again)

Maybe this one then? Using the ‘best fit’ option, it will planarize non-planar curves to the nearest ‘best fit’ plane… (3.4 KB)

However, if the curves are not planar, you will not be able to put a simple planar surface as a ‘roof’ automatically. That means each non-planar curve would need to be surfaced manually with a combination of techniques.

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thank you for the py is it applied?

I like the look that Wim got with grasshoper plugin? which plugin? how can I use this for the rest of the file and can it be exported to autocad or sketchup afterwords?

Hi Ron -

You can download Grasshopper for Rhino 5 from here:
Rhino - Download - Grasshopper WIP for Rhino 5 for Windows (

After you “bake” the Grasshopper geometry to Rhino, you can export it just like anything else.

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so, Wim, did you actually create this “definition” specifically for my task?
thank you so much.
I just can’t figure out how to pick the orange objects, and therefore can’t bake them.

Hello - click on the Preview component and bake from there.


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This did it for me!
I want to thank everyone who patiently answered my questions and helped me here.