[Insight-users] Problem related to the newly submited: Implementation of a 3D thinning algorithm

[Flo]

Dear all:

I tried to use the newly submitted Implementation of a 3D thinning  
algorithm. However, using Colon images, I have wrong results.
A bad behavior is illustrated here: http://florent.chandelier.free.fr/ 
ITK/Thinning_3D_Colon_bad.bmp
A good behavior is illustrated here: http:// 
florent.chandelier.free.fr/ITK/Thinning_3D_Colon_good.bmp
These are obtained on the same object but at different locations.

As you can see, some portion of the skeleton are OK but some others  
are really messy (Zoomed Images). Indeed, I have no holes in my  
object but I end up with loops in the skeleton which thus modifies  
the Euler number.

On a different note, I did myself work on Skeletonization during my  
PhD and *IF* I remember well, lee's paper (the referenced one) is not  
an exact method as pointed out by other papers (cf Pudney, 1997 I  
think. This is due to the cycle process while looking for the  
neighborhood. There is no unique cycle in 3D to go through the  
neighborhood as compared to the 2D case where there is a unique cycle  
- clock and counter-clockwise end up being the same.)

This is a great effort to implement a 3D skeletonization process for  
ITK. Congrats to the ppl doing this. My personal view, and maybe a  
future contribution, would be to spend more time implementing the  
method described by Pudney, 1997 as it allows for the discrimination  
of every skeleton type (Exact medial surface, medial trunk and medial  
axis).

I'm sorry to mail this to the news group but I do not know how the  
reviewing process works.

regards,

flo.