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Explanation of "Max Pixel Radius" in "Find Concentric Edge2"?

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I'm trying to improve how this function is operating and in the Edge Fit Options cluster I saw "Max Pixel Radius". My question is, what does it do?

 

(Using LV2015, so apologies if the rest of you have moved on to newer functions.)

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The Max Pixel Radius is used during the edge fitting. It's essentially an outlier rejection setting. It defines the radius tolerance within which a point is assumed to be part of the fitted line. If a point is more than the Max Pixel Radius away from the fitted line, it's rejected. 

 

The function Find Concentric Edge doesn't show which points are being used as part of the edge fit, but you can recreate Fit Concentric Edge using IMAQ Concentric Rake and IMAQ Fit Line.

 

The image below shows the output of Find Concentric Edge on the left, and Concentric Rake + Fit Line on the right. In the image on the right, dots that are green are points that were used in the line fit, and dots that are red were rejected. 

Concentric.PNG

 

Increasing Max Pixel Radius increases the tolerance of the outlier rejection, allowing more points to be used in the edge fit. Increase it too much, and outliers may start to negatively affect the quality of the line fit.

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Great explanation! I really appreciate you taking the time to post this.

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