Repair STL Mesh

Hello, i am very new to Rhino and Grasshopper.
Currently i try to convert a .stl file to Nurbs but i think i have to rapair the Mesh at first. It’s badly damaged as you can see in the picture… I do not have a good idea how to fix it neither can i find a solution on google because i dont really know what to look for. It would be awesome if someone can help me! Thanks!

Hello- Converting from a mesh is not really ‘a thing’ in most cases - it usually boils down to recreating (reverse engineering) curves and surfaces using the mesh as a reference - in this case, just judging from the image, it may be relatively straightforward but you do need to understand how to model surfaces in Rhino. There may be some shortcuts, like QuadRemesh with SubD output thenToNurbs but probably not if you want clean surfaces.


At first, thanks for your answer! Yes, i tried the quadremesh and ToNurbs already, but my surfaces are very “wavy” as you can see in the new picture. So i tought that i may help to repair the mesh at first. Is that the wrong approach? Thanks for your help, i am struggeling with this task.

Hi @Smiley

Where did your mesh come from?
Once you have a mesh with really bad overlapping faces and non-manifold edges it’s very tricky if not impossible to get a good one from it in a way that preserves sharp features.

Depending on your process, perhaps there is a way to fix the earlier part, where the bad mesh is first generated.

Ideally you want a dedicated reverse engineering tool and it will cost you some $.
If this is a one off project it would be best to contract with a service that can do the reverse engineering for you.

If you plan on getting involved in this as a major workflow in the future, you could try Mesh2Surface which is a plugin that runs inside Rhino. I don’t have direct experience with it myself put perhaps there are others on the forum that do.
Mesh2Surface it is on the lower end of the cost spectrum on reverse engineering tools. Some are easily over $10K.