6 edges blend


Please help to create the surface G2 between 6 edges. The Patch works no good((((


The file:
6_edges_blend.3dm (126.6 KB)

Hi. This can’t be done. The curvatures of the surfaces don’t match at the points of contact. See the attached and notice that the red and blue curvature arcs are very different.6_edges_blend_with curvature.3dm (76.3 KB)

I think it would make more sense to arrange the trims
so that the blend surface you want looks like this:

4_edges_blend.3dm (86.3 KB)

Thanks for the replies! it’s so pity(((( How about Virtual Shape plugin?

Maybe I’m reading your response incorrectly, but no. It is not a Rhino limitation. It is mathematically impossible.

VSR makes a mess of this.

Interesting how VSR is able to blend the surfaces if it’s mathematically impossible…
sometimes even if surfaces are not as expected, it’s nice to be able to close the surface and removing naked edges.
Spent couple of hours today trying to close naked edge… really small thin surface got between…

If you model things correctly with appropriate tolerances, “naked edges” should never enter the equation.

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Yes… I’ll aim for that. Should have checked for small edge that was left behind before moving further…

Perhaps I am mistaken, there are similar solutions for other CAD, so is it mathematically possible? Why is possible for the Patch and impossible for the Network?

Is it made of a single-span surface? Can you upload the file?
Maybe there is a problem with plug-in settings?

Sorry, can’t find where is a mistake in my model?

I made as you suggested 4 edges in other direction. It is better but not perfect.


there are multiple strategies involving 2 or more surfaces to corner fillet such 6 sided situations. It is pretty common having more than 4 edges. However all strategies demand a clean set of “base” surfaces, forming “theoretical edges”. It is a common mistake to trim the outlines of a corner blend in first place without having a theoretical edge or corner “under the hood”. Ideally, base surfaces do positional match everywhere …at least being close to it. For someone helping, it is nearly impossible or at least annoying to reverse engineer the theoretical edges without having a bigger image on the problem.
If base surfaces are crap, your blend gets even worse.
I’m no Alias user, but Autodesk made a good documentation on some very basic universal rules: https://knowledge.autodesk.com/support/alias-products/getting-started/caas/CloudHelp/cloudhelp/2016/ENU/Alias-Tutorials/files/GUID-21501AEB-9E7A-4F9F-A0B3-0A4B3431B9BD-htm.html
So for better help. improve your data first.

Best regards,


He didn’t say that no surface can be created. Making the surface G2 at the corners is the impossible part since the blend surface can’t match both surfaces so that constraint will have to be compromised , Even G1 continuity is impossible because the surface normals don;t agree at all the corners.

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The surface highlighted in pink has a very twisted structure,
If that surface was well behaved you would get better results

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That was meant as a general comment.

Like others suggested, the underlying geometry (initial curves and then the surfaces built from them) needs to be of good quality to begin with. Then, you can work out a patch layout strategy. And then you can start modelling. Often, the model is off to a bad start, creating all sorts of problems further down the line. Try to think like a good old design model-maker.

Hey @XNurbs…can your baby shine on this OP contortion above?

_”There are three methods to gaining wisdom. The first is reflection, which is the highest. The second is limitation, which is the easiest. The third is experience, which is the bitterest. _”


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I believe that I have the right surfaces. Between surface #1 and #2 I use the Surface Blend G2. then I cut it and I want to connect 6 edges. I want too much?

I tried with MOI , not perfect but pretty good job, better than VSR i think.