[vtkusers] VtkConnectivity filter

[David Gobbi]

Hi Richard,

If your data is a volume, then vtkImageThresholdConnectivity might be
more suitable.  It requires you to set seeds, though, and I'm not sure
if that's what you want.

I also have a filter in my personal collection that selects image
regions based on size (rather than requiring you to set seed
locations) and I could potentially contribute it to VTK.  Internally
it computes labels for each region, up to a max of 254, and the code
could be modified so that it outputs the labels.

 - David

On Tue, Mar 12, 2013 at 5:43 AM, Richard Frank <rickfrank at me.com> wrote:
>
> I'm having trouble understanding the usages of the connectivity filter.
>
> I'm trying to use this filter to find and filter out regions in a volume, as one might do with bwlabeln() in matlab....
>
> What does AddRegion() do? Does that usage imply that I already know how many regions there are? Why/when would I use DeleteRegion()?
>
>
> If I ask for all regions, I get the whole volume even if I set a tight scalar threshold. If I ask for the largest region, I get what I would expect,  but that's not what I need.
>
> If I set specific regions, and add 0,1,2 and use a threshold that I know should work, I get nothing.
>
> So, I guess I don't understand the correct use.
>
> Any advice welcome.....
>
>
> Thanks
> Rick Frank