[Insight-users] Mask boundary to ordered set of points

[Radhika Sivaramakrishna]

Hi Benjamin and Raghu,
Thanks for both your suggestions. These are very helpful.
I can get the seed point on the edge (in a similar way as Benjamin
suggested). And my region is very simple with no holes, and it is a single region. Given this starting point on the edge and assuming a simple single region, then is there already an ITK function available to get the ordered list of points. Raghu, is your tool implemented with ITK filters?
Radhika



-----Original Message-----
From: Raghu Venkatram [mailto:raghu.venkatram at gmail.com] 
Sent: Thursday, November 04, 2004 7:37 AM
To: king.benjamin at mh-hannover.de
Cc: insight-users at itk.org; Radhika Sivaramakrishna
Subject: Re: [Insight-users] Mask boundary to ordered set of points

Hi Radhika,

I did something similar couple of months back
http://ct.radiology.uiowa.edu/~jiangm/courses/dip/html/node126.html

the above link gives a very simnple boundary tracing algorithm, use
the 8 connected method.

I am assuming that you have already segmented and done some edge
detection. I used the above method to get teh boundary points, to do
this you need a seed point on your edge.

Thanks,
Raghu



On Thu, 4 Nov 2004 11:00:34 +0100, Benjamin King
<king.benjamin at mh-hannover.de> wrote:
> Hi Radhika,
> 
> I needed such a thing and made it myself als follows:
> 
> 1) Find bounding box of the object, cut with itk::RegionOfInterestImageFilter
> 2) Erode
> 3) Get border pixels by subtracting the erosion from the original
> 4) Iterate the result image and push all points in a std::vector
> 
> I iterated the whole region, but probably you can use a variant of
> itk::FloodFilledFunctionConditionalConstIterator as well.
> 
> > Or is there any function, where if you start from a boundary point, you
> > can move in a specified direction (clockwise or counterclockwise) and
> > get an ordered set of indices visited?
> This requires a border that is equivalent to a circle. Only two-dimensional
> objects with just one component, no holes and no thin (i.e. one pixel wide)
> areas meet this requirement. I don't think, there is a special class in ITK
> for those.
> 
> Hope it helps,
>   Benjamin
> 
> --
> Benjamin King
> Institut für Medizinische Informatik
> Medizinische Hochschule Hannover
> Tel.: +49  511  532-2663
> _______________________________________________
> Insight-users mailing list
> Insight-users at itk.org
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>
 
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