How To Rebuild A Sub-Divided PolySurface Into A Single Clean Surface


I’m trying to rebuilt a series of sub divided polysurfaces into a single surface, so they can be used for grasshopper. The rebuilt surfaces need to be the same form as the sub divided polysurfaces.

The problem is I am having trouble to on how to rebuild them? I know the network surface command is the way to go. However, for some reason it keeps failing to rebuild the surface


Rhino File: Reference_Surface.rar (18.4 MB)

Sorry to chase this up, but does anyone know a solution?


Well, here’s one thing you can look at:

I personally would stay away from the whole crv network thing.

In fact, if/when you have time, check out this tutorial series about Surface modeling.

(URL)Primary Surfacing: A NURBS Tutorial Series in Rhino3D - YouTube

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What is it you need to do in Grasshopper? I think your best bet is to either change your approach in Grasshopper or work with a mesh version of the geometry. Creating a single, trimmed NURBS surface the matches what you have here, is going to take an insane amount of manual point editing!

Hi @adam_murray272
Here’s one way to get started, but it’s not going to be super precise. Hopefully one of the bigger brains will chime in. Depending on the settings in Patch and Quadremesh you can get pretty close to the original surface, but I don’t know what kind of tolerances you have (if any). Again, I would probably look into why a single surface is needed. Can you work with the original Sub-D surface instead or use a mesh extracted directly from the Sub-D?



NetworkSrf has a fundamental requirement on the input curves:
All curves in one direction must cross all curves in the other direction and cannot cross each other.
Your input curves do not meet this requirement.

Using Patch as suggested by Jakob is probably the best way to obtain a single, trimmed surface which will be close but not exactly match the polysurface.

These particular surfaces are going to have a diamond pattern from the LunchBox plugin. The problem is I can’t just use to mesh/sub-d and convert it to surfaces as the grid is too dense and results irregular. I thought this solution is the way to go. But it seems to be more difficult than expected!

Okay, after trying a few ways of creation, patch seems like the best option to go, I’ve got pretty close with the result. However, do any of you know how to remove excess points one the surface is trimmed? I need to make some small adjustments in some areas.

Patch result:

Excess Points:

The best way to do this is just to re-model it properly from scratch, using your initial messy attempt as a reference. That Patch surface is useless for further point-tweaking and really shouldn’t be used for anything ever. There’s no magic “turn this into something useful” command.

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I already a clean mesh model I produced in Maya, so creating a clean model is not the problem I am experiencing.

Maya Model:

I just want to extract these faces into a single surface for grasshopper, so I can use the panel tools in Grasshopper

Reference Surfaces:

I can’t use mesh because grasshopper wants the component to be a surface. it’s also not feasible to convert the mesh or subd into a surface because then I’ll end up with 1000’s of different individual surfaces and non will create a clean pattern.

Mesh input:

SubD Input:

Grasshopper grid when converting mesh/subd to surfaces:

So it has to be a surface, the issue is I’m unsure how to do that with such a complex surface. I’m just wondering what would be the best way to achieve the result

Well, no, you need a proper NURBS model, that follows proper NURBS modeling rules. There’s no magic way to cleanly convert an arbitrary mesh into a single nice surface.

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I see, what would be your suggestion on how to model a complex surface? the methods I know will cause breaks in the surface or won’t be very accurate.

You can try QuadRemesh to get a clean mesh with a nice enough topology. From it, you can go to SubD and from it to Nurbs. But alternatively, you can directly manage and edit your panels from the QuadRemesh tesṡelation.

Im also stuck with same problem but mine is way more complex than yours. In the journey to find solution i found another plugin better than lunchbox. Its called “Ngon” . It uses mesh to make panels.
Hope it might help u.
Ngon plugin