Algin complex nurbs in rhino - how?


Sorry if this seems quite a straightforward question to do, but I am very new to Rhino and I couldn’t find any workaround on the internet for my problem.

I am trying to create a 3D model of a complex soil stratigraphy like the one below. The goal is to use Rhino to create the NURBS surfaces of the top layers and export to a 3D FEM software like PLAXIS 3D to create the volumes ( see e.g

As you can see from the picture above, some soil layers will intercalate and intersect to each other at some point. In some case these NURBS surfaces will intersect and convergence in some region

My question is: how can I optimize the NURBS surface so they can perfectly align in the intersected area? This is important to avoid any small gaps/opening that can cause intersect or numerical issues?

I have upload an example of the surfaces here:

Any help is more than welcome at this stage


usually i would suggest do use some sort of cloth simulation with collision, digging a little around i found that cloth simulation actually also was done with nurbs, but i have no experience… maybe @DanielPiker has an idea?

Hello - not sure if I am answering the right question but one way that comes to mind is to pick one of the two surfaces where they nearly coincide - say the blue one , split both- I used a pipe to trim, from an approximation of the intersection, so it would leave a gap. Then BlendSrf the white one from its split edge up to the split edge of the blue - you can then Untrim the blue to get the whole thing back and the white one will just meet it.

test rhino_Maybe.3dm (1.5 MB)


I…don’t think this is going to work with a NURBS approach, no matter how fine the patches are where the layers get close and have significant slopes you’re going to get weird effects from the limitations of a ‘draped’ surface. Of course that’s exactly what the PLAXIS guys tell you to do, but their example MASSIVELY smooths out the mesh data to where it’s just a vague suggestion. Is the original mesh data in your attached file?

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