[Insight-developers] submission: ApproximateSignedDistanceMapImageFilter

[Lorensen, William E (Research)]

Zach,
Thanks. We'll put this one in after the release.

Thanks,

Bill

-----Original Message-----
From: insight-developers-bounces at itk.org
[mailto:insight-developers-bounces at itk.org]On Behalf Of Zachary Pincus
Sent: Friday, February 04, 2005 5:52 AM
To: insight-developers at itk.org
Subject: [Insight-developers] submission:
ApproximateSignedDistanceMapImageFilter


Hello,

Here's a submission that (partially) addresses bug 737 
(http://www.itk.org/Bug/bug.php?op=show&bugid=737&pos=0 ), and ITK's 
need for a filter that can generate a signed distance map.

Such signed distance maps are required for creating PCA shape models 
with the PCAShapeModelEstimator class, which is in turn useful for 
doing anything really interesting with the 
ShapePriorSegmentationLevelSetImageFilter family of classes.

This may only be a partial solution because bug 737 requests a signed 
distance map based on the Danielsson filter. This submission returns a 
map created by using the IsoContourDistanceImageFilter and 
FastChamferDistanceImageFilter classes. The practical upshot of this 
difference is that this class is faster, but does not compute distances 
as accurately as the Danielsson filter.

Now, it's likely that for PCA shape modeling this difference in 
accuracy might not matter a whole lot: most of the action takes place 
around the narrow band near the zero-level set, which is where the 
Chamfer distance is most accurate. So perhaps this is all the solution 
that's needed. I'm not really qualified to say if it is good enough for 
all practical uses.

Finally, I know it's right around the ITK 1.10 deadline. I have no 
expectation that this should be added for 1.10, of course. It just so 
happened that I wrote the filter now.

Zach Pincus

Department of Biochemistry and Program in Biomedical Informatics
Stanford University School of Medicine