[Insight-users] SignedDanielssonDistanceMapImageFilter Very Slow on 3D Volume?

[Chad Stanford]

Hello,
I'm new to ITK, but have managed to implement a custom level set segmentation filter by deriving from the SegmentationLevelSet classes.  In my case I am provided a rough initial mask that I feed into the SignedDanielssonDistanceMapImageFilter to get the initial level set input.  This step works almost instantaneously when I test my code on 2D slices from a volume in analyze format (.hdr/.img).  However, when I try running my code on the whole 3D volume (only 256^3 voxels) the SignedDanielssonDistanceMapImageFilter takes at least 30 minutes, possibly much more because I get impatient and stop it before it finishes.  
Does anyone know if it is normal for the filter to perform this way on volumes and if not why this might be happening and/or how I can fix it or get around it? 
The volume seems to be read in fine because I can read it in, output it again and visualize the output fine.  Tracing through the code shows that it seems to be getting stuck in the while loop beginning on line 408 in the GenerateData function in itkDanielssonDistanceMapImageFilter.hxx .  I am running the code in debug mode, but over 30 minutes seems excessive nonetheless.

Any ideas?!? 		 	   		  
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