Rebuild Polysurface

I have built a polysurface geometry (like a mold) in Rhino and there are many spots on this polysurface that have very acute angles (as you can see in the red circles in the section). Is there any way to “rebuild” the surface and get rid of all this geometry?

Hello- yes, most likely, but without an example file it’s hard to say more.


test.3dm (14.2 MB)
Here is the file.

How did you create the model?

Did you start with a mesh and then use ToNURBS to convert each mesh face to a separate NURBS surface? If so it may be preferable to work with the original mesh.

Do you want to keep the bumpy surface of do you want a smooth surface?

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the original geometry was a photogrammetry model which is a mesh. In order to construct the “mold”, I went through different phases. Working with meshes was a bit difficult especially with the meshboolean and mesh trim/split commands. So, I made a turn and convert the original photogrammetric model to a polysyrface (I quadremeshed it first).

The inner bumpy surface is the imprint of the photogrammetry model ( after quadremesh and meshtonurbs). In this stage, getting rid of the acute edges is more important than losing some detail in the inner surface.

Here is the original photogrammetric model and the geometry I am trying to build.

So, you are shooting for the object with the rough cavity, including the roughness, but rounded edges, at least in some places, correct?


Is something wrong with the steps I made? Is there any other method I could follow in order to have better results?

Hello- it is just that it is hard to finish the job cleanly with all of the hundreds of facets - if you can make the cavity from a more ‘normal’ set of surfaces, you could lilely aff FilletSrfs all around the hole to clean up but with the angled factets that become quite a tedious business - I’ll see if I can think of something, if David does not do it first.

@SavPant - I would think about a Patch surface, possibly on parts of the original mesh -

is there any chance we can get that mesh, here (public) or to directly ? (with a link back here in your comments)


I understand.
Thank you both for your help.

Hi Savvas - do you care if the result is a mesh rather than a polysurface?


Hi Pascal,
Not at all.