[Insight-developers] Unit tests - Smoothing difference between standard and diffeomorphic demons

[Luis Ibanez]

Hi Hans,


Yes, indeed the initial deformation field is not always null.

I was referring to the specific case of the circle tests that
we have in Testing/Code/Review, and for which we were having
trouble getting them to pass when using the new Demons classes.
My apologies for not being clear enough.



It's great to know that a new Demons implementation will soon
be available.



    Thanks for sharing !


        Luis


-------------------
Hans Johnson wrote:
> Luis,
> 
> You assumption that the initial transform is null is not always true.  In
> many cases the demons algorithms is just one component of a multi-algorithm
> registration framework.
> 
> ====
> With regards to when smoothing should occur, there are three indepent
> choices:  Smooth initial deformation field, Smooth during iterations, smooth
> final deformation field.  These are not exclusive operations.  If this were
> done, then the current Demons class in Algorithms could also be modified in
> a backwards compatible way so that the default behavior remain the same
> (That is until ITK 4.0 where we would be allowed to make default behavior
> changes :-) ).
> 
> ====
> 
> A post-doc in our lab is currently trying to reconcile differences between
> the different demons implementations.  As part of this effort he will be
> stress testing the code quite extensively.  We will let you know if there
> are any problems that occur.
> 
> Thanks,
> Hans