[Insight-users] itkBSplineSyNImageRegistrationMethod - - metric value

[Nicholas Tustison]

Hi Emma,

Yes.

The SyN methods and time-varying velocity field image registration
methods handle their own optimization since they don’t fit into the 
generic optimization framework.  However, they still allow for 
reporting per iteration.  If you look at

https://github.com/stnava/ANTs/blob/master/Examples/itkantsRegistrationHelper.hxx

and go to line 2641, you can see where we start setting up the 
BSplineSyN transform.  Towards the end of the set-up (line 
2802), we use the itk::Command mechanism for reporting
progress to the screen.  
 
https://github.com/stnava/ANTs/blob/master/Examples/antsRegistrationCommandIterationUpdate.h

Go to line 93 where we call

filter->GetCurrentMetricValue().

Nick


On Jan 17, 2014, at 1:01 PM, Emma Saunders <emmasaunders123 at gmail.com> wrote:

> 
> Hi,
> 
> I am new to the itkv4 framework and using itkBSplineSyNImageRegistrationMethod. Without using the ANTS framework is it valid to monitor the optimization simply using in a command iteration observer
> 
> filter->GetCurrentMetricValue() << ", ";
> 
> The reason I ask is I understand multiple registrations are calculated to some midway point using this method, so confused as to what this call will return, if anything sensible?
> 
> Thanks for your help
> 
> Emma
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