LabVIEW Idea Exchange

cancel
Showing results for 
Search instead for 
Did you mean: 
b.ploetzeneder

Vision: Curvature for "closed" contours

Status: Declined

Any idea that has received less than 4 kudos within 4 years after posting will be automatically declined.

Curvature in NI Vision has a property that makes a lot of sense: "If the current point is too close to either end of the array to choose the additional points, the curvature is calculated as 0." (Vision Manual).

Too close refers - obviously - to ~0.5 Kernel size.

 

curvature.png

 

This makes no sense when I'm working on an contour that is "closed" (starting point = ending point) - for example, when I am trying to analyse a particle and its "turning points". 

 

 

I'm losing 1 kernel width of data at exactly the starting point/end point - as marked in the picture - and in this synthetically generated and exxagerrated case, I'm losing the information about one edge!

To fix this, I either rotate the ROI or change the search direction, calculate the missing data and replace the values in the curvature profile. (Or - calculate the curvature myself.) 

This makes absolutely no sense. 
Vision could easily recognize starting-point = ending-point, or just allow me set some boolean if there is a reason not to make this automatic. (I can't think of one.)

 

1 Comment
Darren
Proven Zealot
Status changed to: Declined

Any idea that has received less than 4 kudos within 4 years after posting will be automatically declined.