[Insight-users] Big-O time complexity of level set segmentation?

[Joshua Cates]

Hi,

You should see little difference in total time seeding regions 
one-at-a-time or all together.  Computation is order N, where N is number 
of points on the level-set surface.

Josh.


On Fri, 12 Mar 2004, Zachary Pincus wrote:

> Hello,
> 
> Does anyone know what the approximate time complexity of the level set 
> segmentation methods in ITK are?
> 
> I ask because I have a task that involves segmenting multiple cells per 
> image field. I can either segment each cell separately (grow a new 
> level set for one cell, then the next, etc) or segment in parallel 
> (seed the level set at, say, the centroids of every cell at once). 
> Which methods is preferable depends on the big-O time complexity of 
> level set segmentation.
> 
> For example, if the level set methods are, say, O(n log n), where n is 
> the size of the front, then it clearly makes sense to segment each cell 
> individually. If the complexity is O(n) then it doesn't matter whether 
> you do each cell individually, or all in parallel. And of course, if 
> it's O(log n) then there is substantial time savings to doing the image 
> at once.
> 
> Does anyone have an idea about the complexity of these methods, as 
> implemented by ITK?
> 
> Thanks,
> 
> Zach Pincus
> 
> Department of Biochemistry and Program in Biomedical Informatics
> Stanford University School of Medicine
> 
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