What is the algorithm of NIVision's circular/ellipse detection

[Lucas.Chen]

Hi,

I recently tried a circular/ellipse detection using OpenCV fitellipse and NI's shape(circular/ellipse) Detection using an incomplete circle image.I found

1. NI's results much better than OpenCV. 

2. Find Circular Edge get a little different result with shape(circular/ellipse) Detection.(Circular and ellipse detection in Shape Detection obtained the same result.)

I wander what is the algorithm behind the 'find circular edge1' and circles/ellipses of 'shape detection 1'. If you can show me the link or the clue I would be great appreciated. 

[udka]

Please look in the below link and referred links in the post:https://forums.ni.com/t5/Machine-Vision/What-s-the-differences-between-quot-IMAQ-Find-Circular-Edge-...

[Lucas.Chen]

thanks for the reply. I am sorry I still can not find the algorithm of the circle fit from the link. I tried the least square fit, but the circle fitted result was much worse than NI's find circle algorithm (as you can see the my last uploaded image). I just curious how NI's find circle can achieve so good fitting result.