Roundness calculation

[[Me...]]

Good morning,

I was wondering how the characteristic of roundness is calculated by Calypso? I first thought that it would just be difference between the max and min measurements of the circle, but it appears that is not the case.

[[Da...]]

It actually max = min, the important thing is the fitting algorithm, which should be Chebyshev (also called minimum zone).

[[SH...]]

I think, according to standard it should be the radial distance between MIC and MCC .

[[Mi...]]

In training they said it creates to concentric circles, and "inflates" one from the inside while shrinking one from the outside until they both touch the extreme points of the feature. This is the "minimum zone" method Dane mentioned.

16Circ-D012-Handout-D.png

[[To...]]

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MIC and MCC would use the 3 highest and 3 lowest points. Roundness uses 2 concentric circles containing all points and is the difference between the single highest and lowest point. Hope I am saying that correctly.

[[An...]]

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[[An...]]

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[[Da...]]

Thanks Andreas. What is still missing is the Chebyshev's equation.

Someone dare to throw numbers from Andreas to? -> https://en.wikipedia.org/wiki/Chebyshev_distance

[[Kl...]]

Short PP with the different conditions for the element calculation using the example line.
These conditions also apply to circle and all other elements (if functionality is available).

[[To...]]

Here's a good youtube video on roundness but at 12:43 in the video, where he discusses the minimum zone, he does not clearly state that the 2 circles are concentric but you can clearly see that each circle is only making contact with extreme lowest and highest single point, not the Max Inscribed and Min Circumscribed.

https://youtu.be/NjbvOTUSqdI

Update: I stand corrected. I was wrong about by observation mentioned above. After watching the video again, the minimum zone shows the 2 circles making contact in 3 places. And the resultant roundness was the deviation between the min circumscribed and max inscribed circles. I still am of the opinion this is incorrect. Using that logic, how do I evaluate the 2 circles below?

Screenshot 2021-07-29 055756.jpg

[[To...]]

From Zeiss

Screenshot 2021-07-29 092823.jpg