Creating a Brep or surface from curves on Rhino or GH

Mahdiyar should be hired by McNeel for all the help he provides.
Keep the good work!


Thanks again, this was great.

Yea I definitely agree hahah. Very helpful indeed!!

Sorry there’s just one issue I just realized now. The resultant shape is still a trimmed shape meaning I cannot panelize it with isotrim. Is there anyway of achieving this shape without needing to use trim commands?

No, you have curve “face” outlines which imply more than 4 edges.

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In that case what are my options if I want to panelize this object?

break it down into 4 sided edge surfaces or panelize the untrimmed uderlaying surfaces of the trimmed surfaces and then trim the panels with the face outlines.

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I’m sorry I don’t fully understand how to trim the panelized untrimmed underlying surface. I’ve included my attempt on GH bu I think my approach is not what you meant.

trimming the panelized utrimmed (101.4 KB)

awesome video thanks for sharing @Mahdiyar

Something like this at the simplest. Depending on specifications, things can get a lot more complex (aligning seams, thickness, corners, special conditions), the kind of stuff usually resolved by teams for months for a constructable result.

trimming the panelized utrimmed (104.9 KB)


I similar answered this 2 days ago… But instead of saying that he did not understand he simply opened a second thread and started asking the similar question again and again. He refuses to accept that there is no good solution with isotrim. There is absolutely no point in changing the surface to be untrimmed just for paneling issues. In order to help, people actually need to know what he is planning to do otherwise its a waste of time…

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I feel like this trimmed / untrimmed, panalize brep thing has come up a lot in the forums lately (maybe it’s some homework somewhere). To me it just expresses how important it is to understand Rhino before going to gh, and to understand what nurbs is in general before trying to manipulate it.


I do recall your reply the other day and I attempted your solution of projecting the panels onto my surface but I wasn’t pleased with the result. I opened the new thread not to try and avoid your answer or because I misunderstood it but because I thought that re-creating the surface in rhino would remove the need for using a trimmed surface to begin with (I thought it was a different issue to ask about), but due to my limited experience I didn’t realize that rhino would also require trimmed surface commands to produce the shape. I do however see your point about needing to be clear with the final purpose for the surface in order for everyones time not to be wasted and that is something I will try to make sure I mention in future posts.

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It’s not a question of specific homework but rather isotrim is the basic way we architecture students are taught to panelize a surface in GH. This of course however overlooks using trimmed surfaces. Even though we are taught the geometric basics of NURB it’s difficult at this stage to understand how those geometries work in the software. I 100% agree though that understanding the software better would have helped me avoid this issue completely. Although like you said, this issue springs up frequently on forums which begs the question of what workarounds could be devised in new updates to deal with the issue? Of course the lack of such a feature is probably the result of further mathematical and geometric issues that I am not aware of, but it would be super useful I think. Also thanks again for your help earlier I was going about your solution completely wrong in my script haha.

I believe there is no tool for it because it is a task with too many variables. These variables are all directly related to design intent. You will notice most tools provided by software can perform a type of predictable task. There are infinite ways you can decide to split up a non 4 sided geometry and no one algorithm can solve it the specific way each person may need it. This comes to the point in software where you develop a “workflow” depending on your problem, this could involve custom tools or definitions of your own and these tools you make probably won’t work for the next persons problem. You can however reliably resolve a 4 sided geometry as a grid (iso trim).

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Yea I see what you mean about there being too many variable for such a tool. I guess I just need to get some more experience with new ways of splitting geometries.

Hey, here is a quick example to show you how to panelize a trimmed surface. Of course this is just one way of doing things… (50.6 KB)


Hi Tom,

Thanks for the example it’s a cool approach and much more refined than the way I was trying to project the subdivisions. But if you don’t mind me asking, what’s the point of using construct domain and then making ranges and culling points, instead of using divide domain and number sliders for UV?

I don’t know, there is no advantage.As I said, for any method, workflow or paneling strategy there is an alternative. I already forgot how to use native Grasshopper :slight_smile: Usually I would have directly scripted this in a way that I have more freedom in internally spacing the panels…


Ah I see haha :slight_smile: Thanks again for the example.