# Surface with curve network

**URL:** <https://discourse.mcneel.com/t/surface-with-curve-network/61046>\
**Category:** Rhino for Windows\
**Created:** [April 20, 2018, 6:11pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046 "2018-04-20T18:11:20Z")\
**Posts on this page:** 16\
**Page:** 1

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**Author:** ![paul\_duterque](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/paul_duterque/32/736513_2.png) [@paul\_duterque](https://discourse.mcneel.com/u/paul_duterque)\
**Post date:** [April 20, 2018, 6:11pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/1 "2018-04-20T18:11:20Z")

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Hello everybody!

I would like to create a surface with a network of curves but for some reason it doesn’t work.

 ![Untitled-1](https://global.discourse-cdn.com/mcneel/original/3X/c/5/c55912e0a1809b0e504f33ba0f74a7041aa44dff.jpg)  
[curve.3dm](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/3/2/323fa6b978d2f27bae8cb373f671da0ceac0848b.3dm) (33.9 KB)

I think it’s because it has more than two “direction”. Is curve network will work for this case? if not what would be the appropriate tool for creating a surface around these curves?

Enclosed the file,

Thanks in Advance!

Paul

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**Author:** ![pascal](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/pascal/32/479395_2.png) [@pascal](https://discourse.mcneel.com/u/pascal)\
**Post date:** [April 20, 2018, 6:14pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/2 "2018-04-20T18:14:20Z")

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Hi Paul - there isn’t a way to make _a_ surface from the curves - it will need to be multiple surfaces and a bit of planning. Nice challenge…

-Pascal

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**Author:** ![Michael\_Pryor](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/michael_pryor/32/489117_2.png) [@Michael\_Pryor](https://discourse.mcneel.com/u/Michael_Pryor)\
**Post date:** [April 20, 2018, 6:15pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/3 "2018-04-20T18:15:28Z")

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Network surfaces requires some implication of U and V directions. That shape you have would need to be multiple nurbs patches. Some links.  
[http://docs.mcneel.com/rhino/5/help/en-us/commands/networksrf.htm](http://docs.mcneel.com/rhino/5/help/en-us/commands/networksrf.htm)

> **[Non-uniform rational B-spline](https://en.wikipedia.org/wiki/Non-uniform_rational_B-spline)**
>
> Non-uniform rational basis spline (NURBS) is a mathematical model commonly used in computer graphics for generating and representing curves and surfaces. It offers great flexibility and precision for handling both analytic (surfaces defined by common mathematical formulae) and modeled shapes. NURBS are commonly used in computer-aided design (CAD), manufacturing (CAM), and engineering (CAE) and are part of numerous industry wide standards, such as IGES, STEP, ACIS, and PHIGS. NURBS tools are also ...

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**Author:** ![Lagom](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/lagom/32/767418_2.png) [@Lagom](https://discourse.mcneel.com/u/Lagom)\
**Post date:** [April 20, 2018, 8:35pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/4 "2018-04-20T20:35:39Z")

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You can likely follow [this tutorial](https://youtu.be/nU044WKGPtE). It’s for Alias users, but the method works exactly the same in Rhino, because also Rhino is a NURBS based software. You only need to model the two different fundamental domains of your total shape, because you have multiple symmetries, so it should be a fairly straightforward bit of rhinoing.

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**Author:** ![paul\_duterque](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/paul_duterque/32/736513_2.png) [@paul\_duterque](https://discourse.mcneel.com/u/paul_duterque)\
**Post date:** [May 10, 2018, 1:55pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/5 "2018-05-10T13:55:50Z")

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Hi,

Thanks for your answers, sorry for the late reply.  
Yes unfortunatly i thought that it would be more complex than a curve network surface…😑 I will try this last tutorial you send Lagom and share the result when done, hopefully it will work 💪

Regards,

Paul

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**Author:** ![Lagom](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/lagom/32/767418_2.png) [@Lagom](https://discourse.mcneel.com/u/Lagom)\
**Post date:** [May 10, 2018, 6:13pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/6 "2018-05-10T18:13:51Z")

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No need to worry, it’s actually not complex at all, if you look at the video, at the principle. Rhino has the tools to do achieve the same result.

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**Author:** ![paul\_duterque](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/paul_duterque/32/736513_2.png) [@paul\_duterque](https://discourse.mcneel.com/u/paul_duterque)\
**Post date:** [May 16, 2018, 6:18pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/7 "2018-05-16T18:18:37Z")

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Hi Everyone,

I tried the tutorial you gave me Lagom, and I have an issue of curvature. when I create the first fraction of a surface and that I mirror it, the other surface is in curvature with the other one but creates a weird junction. You can see with the curvature analysis that something is not right.  
Do you know what could be the issue?

Also i was wondering if there was the same kind of slider for curve blend as for the tool blend surface to have a more accurate way of adjusting the curve than with moving the points? Or alternatively how to be precise using this tool?

 ![curvature](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/2/c/2ca107c02a22e29162d2a885d7ec7ce7ec3cb625.jpg)

Thanks in advance,

Paul

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<div class="post-metadata">

**Author:** ![Lagom](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/lagom/32/767418_2.png) [@Lagom](https://discourse.mcneel.com/u/Lagom)\
**Post date:** [May 17, 2018, 3:18am UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/8 "2018-05-17T03:18:28Z")

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Your original curves have far too many CPs. Always try to use single span degree 5 or 7 curves and only use more when absolutely necessary. Also it helps to keep things like this aligned to the grid and symmetric; it makes it much easier to work with numbers where necessary.

In your case, with the bulge, the intermediate sweep you’ve built is not useful; you can instead build the two different quadrants as such. See the attached file [curve.3dm](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/d/6/d6b6357813d74ce048bff0214860683ac24cca4f.3dm) (191.4 KB)

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**Author:** ![paul\_duterque](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/paul_duterque/32/736513_2.png) [@paul\_duterque](https://discourse.mcneel.com/u/paul_duterque)\
**Post date:** [May 17, 2018, 10:41am UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/9 "2018-05-17T10:41:58Z")

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Thanks for your answer it helps a lot,

-My original curve is made with a blend curve, and this tool doesn’t allow for controlling the number of span. Should i rebuild it by simplifying it? which command can I use it for.

-The part you made use a an extrusion going along the upper crv (see picture). i extruded the same curve on my side, however it’s made of 3 different surfaces instead of 1 on your extrusion, making the crv network not working. did you simplify the crv before extrusion, If yes how did you do it?

 ![curve](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/f/1/f1a81a4e334cc2602e59bd50e28b972fc8da4859.jpg)

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**Author:** ![Toshiaki\_Takano](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/toshiaki_takano/32/483707_2.png) [@Toshiaki\_Takano](https://discourse.mcneel.com/u/Toshiaki_Takano)\
**Post date:** [May 17, 2018, 1:08pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/10 "2018-05-17T13:08:55Z")

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You can just use the rebuild command to assign span and control points.

Is it perhaps issue with continuity of the curve at the points where the split surfaces occur?  
can be checked by gcon command.  
May need to explode the curves first.

To fix you can use match command and assign continuity.

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**Author:** ![Lagom](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/lagom/32/767418_2.png) [@Lagom](https://discourse.mcneel.com/u/Lagom)\
**Post date:** [May 17, 2018, 1:30pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/11 "2018-05-17T13:30:04Z")

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> [@paul\_duterque](#):
>
> however it’s made of 3 different surfaces instead of 1 on your extrusion

I used a single span degree 5 curve and then swept a short line along it.

And, as Toshiaki says, you can/should use the rebuild and match commands.

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**Author:** ![davidcockey](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/davidcockey/32/732604_2.png) [@davidcockey](https://discourse.mcneel.com/u/davidcockey)\
**Post date:** [May 17, 2018, 3:44pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/12 "2018-05-17T15:44:43Z")

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> [@paul\_duterque](#):
>
> -My original curve is made with a blend curve, and this tool doesn’t allow for controlling the number of span. Should i rebuild it by simplifying it? which command can I use it for.

BlendCrv results in single span curves. It uses the minimum number of control points needed to satisfy the continuity conditions, and creates a single single span curve which has degree equal to number of control points minus 1. With curvature continuity at both ends 6 control points and a degree 5 curve result.

> [@Lagom](#):
>
> Your original curves have far too many CPs.

@Lagom How did you determine the number of control points from the screen capture without the file?

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**Author:** ![Lagom](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/lagom/32/767418_2.png) [@Lagom](https://discourse.mcneel.com/u/Lagom)\
**Post date:** [May 17, 2018, 6:16pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/13 "2018-05-17T18:16:55Z")

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All curves should be degree 5 curves (rarely 6 or 7) and a degree 5 NURBS curve always has six CPs, so that means it can be matched for G2 on both ends (if that’s needed). I opened the file you attached at the outset and set the CPs to visible (that’s the 1st thing to do and it usually shows where the initial problems or difficulty may arise).

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**Author:** ![Gijs](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/gijs/32/481553_2.png) [@Gijs](https://discourse.mcneel.com/u/Gijs)\
**Post date:** [May 17, 2018, 7:43pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/14 "2018-05-17T19:43:11Z")

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Rhino 6’s SubD seems to give a quite pleasing result for this particular shape

 ![curve_sg](https://global.discourse-cdn.com/mcneel/original/3X/4/4/44669d7926b0ac107413d39925433edb6ef8ae7a.jpg)  
[curve\_sg.3dm](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/6/a/6abb1ab1aeb438b0f206150e451ccb867451cdff.3dm) (395.2 KB)

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**Author:** ![vikthor](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/vikthor/32/436812_2.png) [@vikthor](https://discourse.mcneel.com/u/vikthor)\
**Post date:** [May 18, 2018, 2:25am UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/15 "2018-05-18T02:25:27Z")

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For more ideas, I enclose my approach

 ![ver](https://global.discourse-cdn.com/mcneel/original/3X/2/f/2fa2f189e0eab50538d5c305e73fd33b4c830d0c.png)  
[curve.3dm](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/0/d/0d87603c80bb43f5d9fe12e77b0bfc62dc5e6ad1.3dm) (924.1 KB)

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**Author:** ![paul\_duterque](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/paul_duterque/32/736513_2.png) [@paul\_duterque](https://discourse.mcneel.com/u/paul_duterque)\
**Post date:** [May 21, 2018, 4:42pm UTC](https://discourse.mcneel.com/t/surface-with-curve-network/61046/16 "2018-05-21T16:42:27Z")

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Hi Everyone,

Thanks for all your answers  
Gijs-\> it looks really good and i didn’t know there was this tool in Rhino, however, you end up with a mesh, and i would like to have a polysurface as i need to then cut it at some places and add some pattern via grasshopper.

vikthor-\> I also tried this earlier but the control of the shape is much more difficult and the shape is a bit messier,

Lagom, Toshiaki, DavidCockey → I tried rebuilding the crv and i end up with the following result, which is already something.

However the junction between more than two surface gets really messy, and the surfaces seems to have lots of “tension” even if they are in curvature between themselves.

I think it’s because of the initial curves i drew, but it’s difficult to understand which curve to draw to get the surface you want, is there a methodology or something to achive this curve finding? I know in alias you can modify the curve and the surface will update but the history in rhino doesn’t allow to do it in the same way.

 ![crv2%20copy](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/4/8/48c8883bfeaa650b20ba704f8c4e098d2fb3a1e2.jpg)

Thanks

Paul