# Surface with curve network

Hello everybody!

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

curve.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,

Paul

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

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

You can likely follow this tutorial. 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.

Hi,

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

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.

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?

Paul

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 (191.4 KB)

-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?

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.

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.

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

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).

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

curve_sg.3dm (395.2 KB)

2 Likes

For more ideas, I enclose my approach

curve.3dm (924.1 KB)

Hi Everyone,