How to keep mesh external skin only

HI

i am driven by need to obtain the external skin of a self intersecting closed mesh

point is that when making weird organic shape with SUBD it is easy to get self intersecting surfaces, When this happen it is most of the times possible to perform booleans operations on the generated NURBS but it is not possible to perform boolean operations on the closed mesh generated from these NURBS

is there a way inside rhino to overcome this problem and obtain a closed mesh that behaves as the generating NURBS when it comes to boolean operations

I think that best thing , also consdering that i will 3D print this solids , would be to obtain the mesh’s external skin and get rid of all inner self intersecting entities , i wonder if there is a rhino mesh command that does this.

cheers

ivan

You could split the Nurbs somewhere on the loop and the perform a boolean union with two or three parts.

For 3D printing, in many cases it is not necessary to have meshes without intersections. Formlabs software for example uses Netfabb to check and repair meshes.

hi Martin and thanks for your suggestion

this sounds like a solution to simple cases but it does not allow me solving more complicated cases like this though :frowning:

Of course my approach is just for simple cases.

How did you create the geometry of that fist?

And try this: https://service.netfabb.com/

If you can’t use this service, post the fist

The only tool i know of that handles reskinning of intersecting meshes is a zBrush tool.

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I would use MeshSelfIntersect command to make polylines from self-intersections of the mesh and I would use these polylines to split the mesh and to remove the intrusions. The cleaned mesh may be good enough for the Boolean operations. The MeshSelfIntersect command is new command in Rhino 7.

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HI Andrew and thanks for your suggestion , i have already tried to use it

again , good solution for simple cases but when things get tricky its hard to get rid of all unnecessary inner entities

I don’t know what it takes and how hard it is under a coding point of view but i think that having a command able to define a single close mesh out of a self intersecting mesh would be very appreciated and very useful only for 3d printing purposes but also to allow more editing possibilites in these meshes.

hope McNeel will think about adding something like this to RH7

cheers

ivan

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HI Holo

thanks for suggestion ,
You mean that zbrush does have a decicated command to perform this task automatically ?
unluckily i dont have zbrush and have no chance to buy it for the time being

I wish there was such a command in rhino

It is unlikely additional new command will be add to V7 as far as I understand… If you want, you can get a trial version of ZB I think it works for 30 day or 45…
if you do, then go to: Tools > Geometry > Dynamesh

image
Depending on your mesh size and density try various settings
[When you hover over a button press Control and a help window will open for that Botton.
(upload://z0QuN2zIG2PmPu2QOONGCU4O0vL.png)

Akash

you can use the Make Solid tool inside Meshmixer . it does exactly what you need and is free.
it will make a single mesh on top of your model where you can set the definition of the mesh freely.

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thanks Diego , I am amazed by the video contents… you’ve made my day Diego , thanks for sharing , cheers

ivan

is quite powerful to fix meshes. I use it a lot with Rhino and SculptGL ( a free sculpt program)

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