connectivity8 or connectivity4 with e.g. imaqParticleFilter()? (example image is attached)

[torbjoen]

I am wondering if I should use connectivity8 or connectivity4 to accurately detect some circular markers.

It is important to keep the internal part of each circle/ellipse as accurate as possible.

Attached is one sample image from a typical scene, including a sample image of a binarized circular marker.

Does the connectivity-setting have any noticeable effect?

[Dustin_W]

In the images you're analyzing, I don't think it will matter too much which version you use - connectivity4 or connectivity8. With connectivity4 you are telling the algorithm to only consider items to be together if their pixels are adjacent - touching on one of four sides as in the following:

X
XOX
X

On connectivity8, the two items are together if thier pixels are adjacent or 'kitty-corner' - any of the 8 surronding pixels as shown below-

XXX
XOX
XXX

For more in depth discussion I would look at the vision concepts manual, that ships with the vision toolkit. Go to Start >> Programs >> National Instruments >> Vision >> Documentation.

[torbjoen]

Thanks, Dustin. I'll just use my current configuration, then (connectivity8).

Torbjørn