Curve network not creating a surface

Hi Everyone,

I am trying to create a curve with crv network with curves I created but it doesn’t work, Is it because of the curves or could it be because of the way I select them? Basically I am trying to replicate the shape on the right. Is there a better way to do otherwise?

Thanks is advance,

Kind Regards,

crv network.3dm (7.4 MB)

The curve network does not meet the requirements for NetworkSrf

From Help for NetworkSrf:

The NetworkSrf command creates a surface from a network of crossing curves.

All curves in one direction must cross all curves in the other direction and cannot cross each other.

That shape cannot be modeled efficiently or effectively modeled as a single NURBS surface in Rhino. (In theory it is possible to model it as a single surface using a large number of control points. However the results would be difficult to modify and could have numerical problems.)

That shape is a good candidate for SubD modeling.

It should be possible to model it as three NURBS surfaces, one for each appendage, connected by blend surfaces. The basic topology of the blend surfaces would be the same as for a Y pipe junction.

1 Like

Dear @Despaul i totally agree with David s great answer.

i would also recommend to go for a sub-D approach as this is more fun / faster / easier to modify:
i suggest the following topology for the sub-D faces

in smooth mode this will look like this

if you really need nurbs surfaces you can still convert sub-d to nurbs

if you don t want to use sub-d:
the red, violett and blue part “appendage” need to be modelled first. - if you know how, with suitable curves _loft is an easy way to do it.
hierachically the green part will be the first transition.
the yellow the last. you might get some first results with _blendSrf

if you want to lern more about surfacing check out the training guides level 1/2

chapter 12 compares different approaches and how to analyse compare them.

hope this helps - kind regards - tom

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Thanks for your answers,
So I tried with SubD and it works great

But I don’t know how to add this kind of detail? (convert to nurbs, trimming but how do I flatten this part without modifying the boundary?)

Also I am concerned about the amount of “patch” that the subD creates when it is converted to NURBS. Even if the surface looks perfect, how do you apply texture with flow along surface or similar tools that only works on single surface?crv network.3dm (11.5 MB)

SubD surfaces cannot be trimmed or split and retain the shape, so any additional modeling involving trims or splits needs to be done by first converting to NURBS and then modifying the NURBS surfaces.

That is one of the disavantages of starting a model in SubD.

How would you take a single rectangle which could be stretched and shrunk as much as desired and wrap it around the shape so that the entire shape was covered? That is the what is required to create a single parameterization of the shape. Rhino has some tools which can be used to create such a mapping. Rhinoceros Help?