[Insight-users] Watershed segmentation -- how to access the detailed results?

[Joshua Cates]

Hi,

The short answer is no.  It's true that neighbor information is required 
for the algorithm, but neighbors are only explicitly calculated after the 
initial segmentation (before the hierarchy of merges is computed).  You 
probably want the neighbors of your final (merged) region, which are not 
explicitly stored anywhere.  

The data you need to compute neighbors is buried in the ivars of the
itkWatershedImageFilter, however, you'd have to pull it out and write a
separate algorithm.  Briefly, the data is the itkWatershedSegmentTable
contained in the itkWatershedSegmenter filter (a member variable of
itkWatershedImageFilter) and the itkWatershedSegmentTree accessible
through itkWatershedImageFilter::GetOutputSegmentTree.

Josh.

On Thu, 1 Apr 2004, Atwood, Robert C wrote:

> 
> Once an image has been processed by the watershed filter, is there
> already a list of the regions and how many voxels are in each one? or
> even which regions neigbour upon which other regions? It seems that this
> information must be generated at some point during the watershed filter
> .. If so, how can this list be accessed? 
> 
> (Instead of iterating through the resulting image array and counting ,
> and locating adjoining regions, etc.)
> 
> Thanks,
> Robert
> 
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