How to check G2 surface continuity deviation?

There is a tool to check the geometric continuity of 2 curves, which tells you the angle deviation in degrees, so you can check how close to your set tolerances you are.


However, I cannot find the same tool for surfaces. Does it exist?

(I know about zebra and the other shading modes for visually checking, but what I’m looking for is the numeric analysis values.)

Hello - in the V7 WIP there is EdgeContinuity

Nothing in V6.
I can give you a plug-in that marks discontinuities though, in case that helps-

MarkSurfaceDiscontinuities.rhp (21.5 KB)

You’ll have to unblock the plug-in

and then drag and drop onto Rhino for the command



Ah, someone mentioned this to me before and I forgot. Thank you for reminding me!

I tried this plug-in now, and even though I’ve unblocked it, the only thing that happens is that the command line gets spammed with a few number 1s…

Also, it seems to only take a single surface… that’s going to be a lot of clicks. :slight_smile:

Hello - does the surface have discontinuities?


I don’t know. That’s what I want to check. :wink:

Well, since the tool is perfect in every way, and you asked it to mark discontinuities and there are no marks…


Hehe. Well, I managed to get different number (2, 3, 4 and 5s) after I extracted the surfaces and tried again, but I don’t understand what they mean. I guess this is perhaps a more rudimentary tool than your planarize/short edges tools that clearly draws nice things in the 3d viewport?

If you give it a surface with discontinuities, you’ll get some lovely stuff added, especially if you ask for details. Also info on the command line.
“Not G2_continuous. Maximum sampled curvature difference 0.212”


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Sorry, but I get this after unblocking, restarting, and using V6 SR19.


I can try on a different computer on monday, and perhaps other users have better luck than me.

Hello - the tool looks for internal discontinuities.


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:man_facepalming: Oops, sorry. I thought it was something completely different. I wasn’t even aware that was something that could happen. I was looking for an easy way to mark continuities between surfaces, so I’ll continue to use V7 for that then. :slight_smile: