[Insight-developers] ITKv4 Tutorial - ISBI 2012 - Barcelona - Wed May 2nd

[Nicholas Tustison]

Hi Luis,

> Are all these underlying functionalities already 
> in the ITK Git repository ?

Yes, the motivation for putting together antsRegistration 
was 3-fold:

1) Considering the quantity of new ITKv4 registration classes 
introduced, we wanted to have something that could illustrate
how the user, I mean ITK community member, could put the 
ITKv4 components together to make something useful.  

2) The registration tests in ITK proper are useful but seeing how 
all the components work together is just as important and might
flush out issues which aren't apparent from the ITK testing.

3) Finally, we had always talked about incorporating the ITKv4
developments back into the original ANTS and this was a 
chance to build a similar registration application from scratch
(which is why antsRegistration.cxx was initially developed under
the code name "hormigita").  

So, yes, antsRegistration only uses ITKv4 components which are
currently in the latest ITKv4.  As patches are submitted with additional
functionality, we incorporate those as soon as possible.  For example,
the Demons metric v4 version was recently introduced which we
then immediately incorporated into antsRegistration.  To make it useful, 
though, one thing we use which is not in ITK git is a collection of our two
small command line parsing classes.

antsRegistration doesn't contain all the functionality intended for 
ITKv4.  For example, the point set metrics are currently missing
although we have a gerrit patch currently posted to address this.  Also,
the parameter scaling doesn't work for the original B-spline registration
(although the registration still works) but there's a gerrit patch posted 
which is meant to address this.

antsRegistration, in some ways, is more flexible than the original
ANTS.  For example, one can chain together several transforms
using different similarity metrics initialized with a stack of transforms
for either or both initial and fixed images in a single command line
call.  We also have a companion piece of code called 
"antsApplyTransforms" which handles the different output transforms 
from antsRegistration using the different interpolators (including a 
couple that we introduced).

Nick