# Edge Continuity tool, how to use?

Is there supposed to be a comb diagnostic display for curvature in the “edge continuity” tool like there is for tangency? If so, how do you activate it?

Even if I put the scale to a million here, I don’t see any comb rising up from the edges…

Yeah - you do have to crank that scale way up - My guess of the moment is that this happens because it was originally indicating a % curvature difference and now that it has been changed to an absolute difference, the scale is too small a lot of the time. I’ll see if there might not be a better way - thanks for pointing this out.
https://mcneel.myjetbrains.com/youtrack/issue/RH-54676
-Pascal

I wonder if I encountered a bug then, because I couldn’t get any comb at all to rise up from the surface. I’ll try again when I get back into the office and if I can replicate it, I’ll attach the surfaces in question.

(Saw the percentage comment as well, and it was absolutely the correct thing to do to move to an absolute difference.)

Don’t go back to percentage scaling.

Perhaps have a default scaling for curvature based on 1 / absolute tolerance or 1 / absolut tolerance squared.

@pascal Suggestion for the curvature comb scale control - The numerical value entered in the panel is the log of the scale used by the algorithm.

Or a percentage of screen size? (The reported values should still be absolute, only the hair length display would be a function of what I suggested.)

That would have the same result and problems as setting the scale as a percentage of the curvature discontinuity.

Another question on this same topic. How am I supposed to interpret this?

The right edge has tangency at 0 degrees deviation… but the left edge also has 0 degrees deviation on tangency, yet shows a comb? And not only does it show a comb, the peak is at 0?

Look at the scale setting. This is a deviation below 1/100 of a degree emphasized by a scale of 100000.
The edges are perfectly tangent.

Mmm… ok… so imo, there should be a different scale setting for tangency and curvature then, because I already reduced that value because the curvature combs were so small…

The only reasonable solution imho is an “autoscale” button, which would adapt the scale to the actual deviation…
I already suggested this in some other thread if I remeber correctly…
@pascal: look at how it works in VSR/Autodesk shape modeling.

As a step, hopefully, in the right direction, the next WIP will have independent scales for distance, tangency and curvature.

-Pascal

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How would that work if the tangency difference is 0.0001 degree? Would the scale then be 10000?

Independent scales for distance, tangency and curvature are essential.

Yes, very much so.
The max deviation determines the scaling factor to show a meaningful graph amplitude.
Works that way in VSR/Autodesk shape - and works like a charm.

Autoscaling would cause the same problem that eobet reported above. The comb would be scaled to make it appear there are significant deviations when all values are very close to zero That is one of the problems with autoscaling. It may “work like a charm” but it would be misleading rather than useful.

To be honest, I don’t follow you here.
I am proposing an autoscale button, so you would click it purposely, knowing that it changes the scale.
It would be there to illustrate the nature and location of very small (or very large for that matter) deviations.
Why anybody would need to check that graph if the deviation is in the order of 0.0001 degrees remains a mystery to me.

They would check because they don’t know if the deviation is sufficientl small.

Optional autoscale would be okay. I just don’t want it to become the default.

But the max value is shown anyway, even when you can’t see the comb graph…