Polysurface to Surface

Dear all,

I received and .step file representing a polysurface.
In order to use this polysurface for further algorithmic compilation, I have to figure out how to transform it into a regular surface. Unfortunately, I couldn’t figure out an approprate way on how to reverse engineer it.
I tried to select the boundary edges, join them to a closed curve and use the boundary surface component but this doesn’t return any result.
Does anyone know other approaches?

Attached you find both the .3dm and .gh files (Rhino 5)

Thank you for your help!

Polysurface.3dm (129.7 KB) PolysurfacetoSurface.gh (24.5 KB)

Your polysurface appears to have been made using Sweep2, anyway, you can make it into single untrimmed surface using pufferfish plugin’s Sweep Unsplit Surface.
But your polysurface has sharp creases and I’m not sure how it can help with your follow-up work just because it’s a single untrimmed patch.

PolysurfacetoSurface_re.gh (47.9 KB)

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here is a quick take at it in Rhino (then imported in GH) result is not perfect though.mergeSrf_smooth=no_roundness=0.gh (69.3 KB)

based on rebuilding the surfaces with Sweep2. You need to rebuild them in order to merge, because trimmed surfacs won’t

Just to avoid confusion, I slightly renamed it to “Unsplit Sweep Surface” in V2.4

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please note that your generated surface is quite different from the original… The surfaces were trimmed

Dear Kim,

The Polysurface is made from an Inventor file provided from a colleague of mine.
It represents a part of a wing geometry that should later get tested in a wind tunnel in terms of aerodynamic properties.

I think your solution could work for me as far as I see on the picture.
But probably the Integer values for each List Item Component slightly differ as my outcome is not an untrimmed surface.
Could you provide further information for which item(s) to choose?

Thank you! :slight_smile:

Please let me know if you need a quote for wind tunnel testing :slight_smile:

4 list items are the 4 corner points of your polysurface
I joined your polysurface naked edges and splited at the 4 corner points, then use two long curves as rail curves and two short curves as section profiles.
I don’t know why item numbers change. What version of the Rhino are you using?

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Great, I got it!

Version 5 SR14 64-bit
(5.14.522.8390, 05/22/2017)

But this problem occured from time to time in the past…

Thank you for your offer but unfortunately (or luckily) we have a wind tunnel with a max. useable cross section width of 2 m and a height of 2 m at our university. :slight_smile:

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Yes. The weird thing is that if I bake the last result from Unsplit Sweep Surface, it’s recognized as a poly-surface in rhino. However, it is still possible to work with a single untrimmed surface in GH. Please let me know if I’m missing something? @Michael_Pryor

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Nice - that’s a good size! Cross sections from 2x4 m to 5x6m here, or up to 10x10m for some applications, e.g. environmental tests, rain, dust and sand storms ! :wind_face: :beach_umbrella:

The Pufferfish unsplit components essentially ignore Rhino’s crease splitting settings. The surface it makes and the expected polysurface are identical in shape (although gh sometimes displays the unsplit weirdly, it is just a display issue in gh with creases). It splits when baked because Rhino has crease splitting on by default. You can turn off crease splitting in Rhino with the CreaseSplitting command. Additionally, you can easily apply the crease splitting back to a Pufferfish unsplit components result in gh with Pufferfish’s “Split Kinky Surface” component. I believe I describe this in all the unsplit surface components output descriptions.


Hi HS_Kim

I was trying to use your gh definition but I get a error with ‘Shatter’ component… could you check this for me…

poly surface.3dm (2.1 MB)