composite transform not maked as modified when using SetParameters

asertyuio · November 27, 2017, 3:55pm

Dear all,

I have a small and maybe silly question. I noticed that when I was changing manually the parameter of the last transform in a composite transform, the composite transform was not marked as modified. For example, after using SetParameters(), I have to call the ->Modified() function to force a resampling filter to rerun.

Is that the expected behavior ?
Thanks,
Yann

tim-evain · November 27, 2017, 4:15pm

As far as I remember, this was always the case.
Modifying parameters will trigger a Modified() on the transform, but not on the filter linking it (the transform doesn’t know which object reference it).
So the filter Update() will see no modification. You have to call Modified() by yourself on the filter.

Tim

asertyuio · November 27, 2017, 4:35pm

What I mean, is that if I use SetParameter() on a “normal” transform, calling update() makes it rerun itself. However, it is not in the case for composite transform.

In the sources, I see that SetParameters() call this->Modified() for the similarity transform for example :

github.com

InsightSoftwareConsortium/ITK/blob/d317254649f3b7819473ceaa0a18c48ed5f0156c/Modules/Core/Transform/include/itkSimilarity2DTransform.hxx#L87


  {
  translation[i] = parameters[i + 2];
  }
this->SetVarTranslation(translation);


this->ComputeMatrix();
this->ComputeOffset();


// Modified is always called since we just have a pointer to the
// parameters and cannot know if the parameters have changed.
this->Modified();


itkDebugMacro(<< "After setting parameters ");
}




template<typename TParametersValueType>
const typename Similarity2DTransform<TParametersValueType>::ParametersType &
Similarity2DTransform<TParametersValueType>
::GetParameters() const
{

but not in SetParameters() of composite transform:

github.com

InsightSoftwareConsortium/ITK/blob/d317254649f3b7819473ceaa0a18c48ed5f0156c/Modules/Core/Transform/include/itkCompositeTransform.hxx#L759


  while( it != transforms.begin() );
  }


return this->m_Parameters;
}




template<typename TParametersValueType, unsigned int NDimensions>
void
CompositeTransform<TParametersValueType, NDimensions>
::SetParameters(const ParametersType & inputParameters)
{
/* We do not copy inputParameters into m_Parameters,
   * to avoid unnecessary copying. */


/* Assumes input params are concatenation of the parameters of the
   sub transforms currently selected for optimization, in
   the order of the queue from begin() to end(). */
TransformQueueType transforms = this->GetTransformsToOptimizeQueue();


/* Verify proper input size. */

But no big deal, I just noticed that, find it weird, so I just tell it instead of burying it !

Yann

fbudin · December 1, 2017, 2:06pm

It indeed seem that it is missing in this filter. All the other transforms that I looked at did implement the update. Would you be willing to submit a patch to correct this issue?

asertyuio · December 1, 2017, 3:03pm

Yep, I’ll do it

blowekamp · December 1, 2017, 3:27pm

This might have been an intentional design with the ITKv4 registration framework.Nick might know for certain.

It might also be expected that the MTime returned by the Composite transform is the most recent of itself AND all transforms it holds. So if one transform in the composition is directly modified then the Composite transform would reflect that it has been modified.