Sigma survey

[[Ja...]]

Just out of curiosity, I’m wondering what the smallest sigma value people use before you consider it to be to the point where you’re eliminating too much data.

[[Lu...]]

My filters are set for plus/minus 3 sigma

[[Pa...]]

I've never considered using sigma for this.  I'm not sure there's an answer.  I mean scan a circle with a gazillion points with any attenuation settings, then come back in and take 5 discrete points at the same location.

They will both have sigma values.  They will both report different results.  I can't use S to determine which is correct.  I know the 5-point method threw away no points.  Maybe use the S value of this as your target?

 

[[Ke...]]

I think I remember someone stating thet a Features Sigma value should be about 25% of it's Form... but IDK where one would go from there.

I'm more of a visual person, so I always "show masked actual points" when I'm programming, and I plot roundness & flatness for important features so that I can see if there is too much filtering