Boolean Union on Structure of Extruded Cubes failed Non Manifold Edges

Hello i hope someone can help me i have generated this structure using isotrim and attractor points in grasshopper and baked it into rhino and want to BU all extruded Cubes into One Hollow strucutre

i asked a friend who uses rhino 5 and for him it worked normally by selecting all closed polysurfaces -> MeshtoNurb->BU
however there are a lot of non manifold edges is there any way to get rid of them and convert the structure to a solid by its outer shapes?

My thought is least trying CreateSolid on the right hand object – I don’t know if it would do the right thing but it might.


u misunderstand me i have the left object and want the right. i have similiar structures and i would like to unify them aswell

Ah, ok - I thought you got most of the way there but it had non-manifolds to get rid of. Is the original input polysurfaces or a mesh?


the original input are a bunch of individual closed polysurfaces

Why don’t you post a file? Or a part of it? It will be easier for someone to help you

Note if you have structures like cubes meeting edge to edge as in the image below, there will always be non-manifold edges - that is just the topology, you cannot eliminate them.

structure.rar (5.0 MB)
thing is i want to do boolean operations with this structure and as it is with its non-manifold edges i cant work with it anymore; every boolean operation fails and/or freezes rhino.
whats wondering me is that a friend of mine could generate the correct structure i want in Rhino 5 (somehow it deleted the inside of the structure and just kept the outer planes (which is what i want to achieve too)

I can’t open rar files.

What you can do to avoid the non-manifold edges is scale all your cubes by a tiny factor. Use their volume center as a center of scaling.

i had to compress it with winrar to not exceed the 20mb limitation
how can i scale all cubes individually, i tried _offsetMesh but it still has the same problem

can you create a ZIP? (7.0 MB)

Ah, those are meshes. The one from your friend is a polysurface. Don’t expect meshes to work well in this case. You might be able to convert the meshes to NURBS using MeshToNurb, then union them (do it in small groups), it may or may not succeed, it will take awhile…

yes he was able to select all MeshtoNurb and then BU, in my case i get a boolean union failed and the error with the non manifold edges

The meshes are good. You can use their boundaries, 6 per mesh, to build surfaces and join these into closed breps.

I scaled the boxes on this example by factor 1.001 in X and Y. This way you get tiny intersections where you would end up with non manifold edges. Solid union takes a moment but it works.

Depending on what you want to do next, this might be an option (133.4 KB)

1 Like

this way i got the polysurface i want, still i cant create this pixelated roof like structure with booleandifference , now the boolean difference fails

cant really sketch it out…
sth similiar to what you posted
i want to boolean difference B(selected) out of a
b is just a copy of a moved a bit in -z

i need the cubes as solids with a thickness again hence the boolean difference i tried

The bottom and most of the Vertical faces of both A and B are in the same places. Boolean difference will not work when faces are flush like that. Make B wider so that is significantly extends beyond the volume of A you want to remove.

no way to have the underside the exact shape as the upper side?
it worked like a charm on the rhino of my friend, even though the planes were in the same places

i created this file to better show my problem
structure.rar (11.2 MB)

i noticed my friend has no problems running all the commands and has no problems with overlapping surfaces (he uses rhino 5) anything that was changed which makes it complicated now?