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##### snap peaks and inflections?

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12-28-2017 01:05 AM - edited 12-28-2017 01:28 AM

Knots and poles of a curve can be snapped for creating some features.

Two questions:

- Is it possible to snap peaks and inflections of a curve?

- For peaks, there are two types of triangular symbol, solid and hollow. What's the difference?

Thanks!

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4 REPLIES

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12-29-2017 11:19 AM

the filled is the point of max curvature. Smallest radius. ( toggle Show comb and / or Show label Maximum to see it.)

You cannot snap peaks or inflections unless you click the "Create Peak points" or "Create Inflection points" in the curve analysis dialog.

Regards,

Tomas

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12-29-2017 01:00 PM

Hi @1u7obd Thanks for your comments!

The difference between the filled and the non-filled should be pretty obvious if you think about it.

the filled is the point of max curvature. Smallest radius. ( toggle Show comb and / or Show label Maximum to see it.)

As stated in the tool tip: **Peak** is where the radius of curvature reaches a maximum.

But as shown in the curvature comb, all the triangles point to where the curvature (NOT radius of curvature) reaches a maximum. I'm really confused.

I still can't see the difference between the filled and the non-filled triangles. Could you kindly give some clues?

You cannot snap peaks or inflections unless you click the "Create Peak points" or "Create Inflection points" in the curve analysis dialog.

This trick is great. But it's a pity that those points are non-associative.

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12-31-2017 12:33 PM

"Curvature" is = 1/radius . Most often this is illustrated by a curvature comb where the 1/r is scaled by a factor and the illustrating comb is on the outside instead of towards radius center. ( you can switch this in the dialog)

The purpose is to aid in designing aestetically pleasing splines, - the outline of the curvature comb is an exaggerated shape of the spline itself, showing the peaks and if there are inflections or undulations in the spline.

Each "bow" of the curve will , since this is a spline and not an arc have a point where the curvature peaks, the point of the "bow" with the smallest radius. There will be point which has the smallest radius of the entire spline. - The filled triangle.

Why / for what purpose do you want these points to be associative ?

Regards,

Tomas

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12-31-2017 12:45 PM - edited 12-31-2017 12:59 PM

Hi @1u7obd

Then, for a single spline only one triangle is filled, which has the smallest radius among all peaks. Am I right?

And how to understand the tool tip on Peaks as "where the **radius of curvature** reaches a maximum"? As shown in the curvature comb, all the peaks point to where the curvature (NOT radius of curvature) reaches a maximum. Do I make something wrong?

As to why I want those points associative, please refer to my previous post match curve details.

Thanks and happy new year!

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