Point editor alert / EdgeContinuity

Hi all - I want to point out a couple of new things in the WIP for Windows that may help you point-pulling surface editor types out there -

  1. EdgeContinuity - a panel that gives you feedback on pairs of surface edges for Position, Tangency and Curvature:

The dialog still needs a couple of tuneups - if you do not see the buttons for adding and removing edge pairs, just make the panel bigger - as of today at least there is no scroll bar. I’m not sure if the release that is out there in public right now has the full set of controls but the next one will.

  1. In Options > Modeling Aids > Nudge page there is a new setting for ‘Control Polygon’ to match the ControlPolygon setting in DragMode:

Please give those a spin and let us know what does not work… You may need to type the entire command for EdgeContinuity as it is still a test command as of today…




Thanks for letting us know about EdgeContinuity. It will be very useful with some refinement.

I assume Tangency and Curvature comparisons are in the directions normal to the edges. Is that correct?

Curvature should be displayed as absolute curvature discrepancy similar to Distance and Tangency, not as some sort of percent. The current percentage display is useless at best for analyzing differences when one of the surfaces has zero curvature normal to an edge. Display absolute curvature differences.

Add ability to change pairs of edges without closing and restarting command.

Add ability to display results for more than one pair of edges, similar to curvature combs generated by CurvatureGraphs.

Enhance the color coding similar to the coding used by PointDeviation. This would provide a quicker evaluation of where the continuity is good, acceptable, bad, etc.

Split off a separate thread for discussion of EdgeContinuity.

Yep, thanks, that’s what we needed, a sanity check.
The other items than the color coding are how it works now…


Thanks for the reply.

Perhaps I’m missing something but that is not how EdgeContinuity works now for me. Once I’ve selected a pair of edges I can only select a different set of edges by closing edge continuity and restarting it. No ability to select and display the results for multiple pairs of edges simultaneously. I’m going to use EdgeContinuity while revising a faceted polysurface and I’d like to see the angles along multiple pairs of edges simultaneously.

But currently it’s a major improvement of what is (not) available in V6 and previous. :smile:

Hi David - I think it’s just not there in the public WIP yet - should be in the next one.


What’s the possibility/probability of the curvature metric being changed before final release to absolute difference rather than the mysterious “percentage”?

Hi David - I think it’s likely to be changed shortly… this was just a first test run.


I found I can add additional pairs of edges by clicking on them after EdgeContinuity is started; just cannot remove them.

EdgeContinuity is very useful and for my current task it is saving a lot of time! Thanks! :grinning:

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I like the idea, but the execution wont offer a good workflow.
It needs to be two seperate tools, not just one, with all options crammed into it.

The Edge Continuity Tool is used to precisely analyse edge pairs while manipulating surface CVs to modify a match.

For example building a feature line with the kink opening up from 1° to 8°. You would do this with a tangent analysis. You need to be able to read the Min and Max points of the kink to make sure it opens up evenly, with constant growth.

You can also modify an existing match to meet certain criterias on one or several edges of the same patch, with “numerical” precision.

Or you can precisely analyse a matching or filleting situation, to help you determine patch seperation and layout.

This not a tool to show you a “good” or a “bad” match, it just analyses continuity.

The Edge analysis tool is used differently. If you have a topology consisting of lets say 36 surfaces, you wouldnt want to select each edge pair. You select all 36 surfaces and run the edge analysis tool to see if the topology meets the given tolerances, and to see where the flaws are.

This tool could be used on two single surface also, to fine tune the match as an added bonus, but the Edge Continuity Tools shows actual values instead of just giving visual feed back.

This tool would also replace the naked edge analysis.

It works this way:

Surface edge pairs (of a topology) that are within the G2 tolerance light up green.
If the edge pair is below G2 tolerances but within G1 tolerances it lights up yellow.
Below G1 tolerance but within G0 it lights up red.
Below G0 tolerance but within N it lights up pink meaning you have a gap.
Below N tolerance “Edge Pairs” are not related to each other.

This is how such a toolset should be designed and used to guarantee a proper workflow and full control over surface quality.

Of course both tools could be running at the same time if the user sees fit in that, but generally speaking they are two differnet tools that might compliment each other.

I made a little mock up:

Edge Continuity:

Edge Analysis:


My workflow using EdgeContinuity would be degraded if the color coding was removed as suggested above. Instead I’d like to see the color coding enhanced as I requested earlier in this thread. I use both the numerical display and the color coding as I modify surfaces. I don’t see any drawbacks to the color coding.

The addition of a second tool for analyzing multiple pairs of edges to determine if continuity meets desired tolerance as suggested by @Cadworx above could be useful.

Please read my post, I considered this already. The drawback is that one is a measurement, which returns values, the other is an evaluation where measurements get checked against a tolerance. Its two different things, therefore it should be kept seperate.

What is the practical reason they need to be kept separate? Or is this based on a general principle or rule about not mixing measurement and evaluation? .

They can be mashed together into one tool, but this would be a total visual overload for such a tool.

Also a workflow must be defined to select objects for such a tool. Do you select single edges, or do you select surface objects and the tool finds the edges by itself?

Furthermore its two different work flows.

Take my example of building the featureline kink. The measurements tell you that the tangent angle gets bigger. The color analysis in this case would show a broken tangent match.

On the other hand, if I try to improve a match by hand, I can read the values, what would I need the color for?

And if you check 36 surfaces at once would you need to see all those deviation values on screen at the same time? N,G0,G1 and G2, maybe even with a Min and Max value each?

Instead you just see 4 different colors telling you exactly whats going on, as you have set the tolerances yourself.

What would be practical reasons to put everything into one tool?
Maybe you make a mockup putting all ideas together.

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I agree with the suggestion for two tools. One tool to check and indicate where continuity exceeds user set values as you suggested above. In some respects this would be an extension of ShowEdges with the Naked edges option. Such a tool could be very useful.

The second tool would be EdgeContinuity with the changes I requested above - the ability to set levels of color similar to the color scale in PointDeviation, and curvature deviation being reported as an absolute difference, I’d like to see it continue reporting numerical value and location of the maximum deviation.

I recently used EdgeContinuity to edit a set of surfaces where the tangential difference between adjacent surfaces needed to be less than 27 degrees. I watched both the numerical value to see how large the angle was, and the colors and comb to see what was happening elsewhere along the edges.

I don’t see why keeping the color coding in EdgeContinuity would preclude development of an “Edge Analysis” tool.

Hello - thanks - your tool 1 is what we’ve got here, more or less, tool 2 would be handy but is a different thing. I can see the need for a crease analysis - that is a little different than what this first cut was considering, so to speak… the idea so far is to help get smoothly matching surfaces, in which case a minimum value is not that useful.

Does the tool as is help with getting surfaces noodled in to some degree of continuity? If not, can you describe what’s missing?


Hello - thanks, I understand all of what you said, and I do not for a moment dispute that more would be grand and desirable. None the less, for now as a tool for helping surfaces get surfaces match up smoothly, it would be helpful to understand what is missing or not working.


At least add the MIN value.

However, as your tool already takes measurements and evaluates them, please just go the extra mile and build something similar to what I laid out above. Rhino would really profit from this in the long run.

This is not a case of " today I would like to have…" Those are useful and proven tools that you will find in similar form in software like ICEM and Alias which are the industry standard tools of high quality surfacing.

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As previously requested:

How do I get the edge colouring (Good/Bad/Max) and the comb graph to show up?
While the command does work and show the continuity values in the dots, the colours/comb graphs don’t seem work for me…

Some thoughts: Edge selecting is tedious. Why can’t we just select two surfaces and Rhino figures out the mutual edgepair itself?
As others have said: A “global” edgecontinuity command is needed to control a bunch of surfaces in one go.

As a VSR/Autodesk shape modeling user I think You should have a look in shape modelings excellent surface analysis tool set.

If You don’t have a copy of “shape modeling” and have further questinons, ket me know.

Cheers, Norbert

Hi Norbert - the scale may have to be much larger than what you have set.