[Insight-users] Fwd: Multi-Resolution Demons with initial Affine

[Emma Saunders]

Hi has anyone any idea why I obtain this behaviour, is it a limitation of
smoothing at every update?

Thanks in advance

Emma




On Wed, Jul 31, 2013 at 9:26 AM, Emma Saunders <emmasaunders123 at gmail.com>wrote:

> Hi everyone,
>
> I'm attempting some multi-resolution demons, as input I use an initial
> affine transform.  When monitoring convergence however, I get peaks at
> every pyramid level (see attached diagram).  Is this normal behaviour
>
>  my pseudocode looks something like:
>
> //Define Demons filter
>
>  RegistrationFilterType::Pointer filter = RegistrationFilterType::New();
>
> //Create initial Affine transform and convert to Displacement field,
> called AffineField
>
>   AffineField=converter->GetOutput();
>
>   filter->SetInput(AffineField);
>   filter->SetStandardDeviations( 0.8);
>
> //use multiResolution
>
>  MultiResRegistrationFilterType::Pointer multires =
> MultiResRegistrationFilterType::New();
>
>   multires->SetRegistrationFilter( filter );
>   multires->SetNumberOfLevels( 4 );
>   multires->SetFixedImage( FixedImage );
>   multires->SetMovingImage( MovedImage );
>   unsigned int nIterations[4] = {100, 100, 50, 50 };
>   multires->SetNumberOfIterations( nIterations );
>   multires->Update();
>
> Am I correct in setting the initial affine field in this manner, does this
> set the affine field for the first stage of the pyramid? or is it a case of
> the affine field being re-applied at every pyramid value and hence peaks in
> the metric
>
> Thoughts appreciated
>
> Thanks
>
> Emma
>
>
>
>
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