[Insight-developers] using VectorInterpolateImageFunction with images of CovariantVectors

[Joshua Cates]

Hi Luis,

Sorry, my email was not very clear. What I'm after is the functionality
you refer to in the second half of your email: support for all
FixedArrays.  I happen to be using CovariantVectors in my particular
application, but I need to represent them and interpolate as FixedArrays
in a parent class.  

Can't we just change 

template <typename T>
struct GetVectorDimension
{
  itkStaticConstMacro(VectorDimension, int, T::VectorDimension);
}; 


to 

template <typename T>
struct GetVectorDimension
{
  itkStaticConstMacro(VectorDimension, int, T::Length);
}; 


and


class ITK_EXPORT VectorInterpolateImageFunction : 
  public ImageFunction<
    TInputImage, 
    Vector< ITK_TYPENAME NumericTraits<typename 
TPixelType::ValueType>::RealType, 
      ::itk::GetVectorDimension<TPixelType>::VectorDimension>,
    TCoordRep > 


to 


class ITK_EXPORT VectorInterpolateImageFunction : 
  public ImageFunction<
    TInputImage, 
    FixedArray< ITK_TYPENAME NumericTraits<typename 
TPixelType::ValueType>::RealType, 
      ::itk::GetVectorDimension<TPixelType>::VectorDimension>,
    TCoordRep > 




Josh.

______________________________
 Josh Cates			
 School of Computer Science	
 University of Utah
 Email: cates@sci.utah.edu
 Phone: (801) 587-7697
 URL:   www.cs.utk.edu/~cates


On Tue, 12 Nov 2002, Luis Ibanez wrote:

> 
> 
> Hi Josh,
> 
> The itk::CovariantVector class was recently modified in order
> to make possible its use with the VectorInterpolateImageFunction.
> ( this happened on 10/23/02 )
> 
> 
> The difficulty was that VectorInterpolateImageFunction access
> the dimension as "VectorDimension" but the CovariantVector
> used to call its dimension = "CovariantVectorDimension".
> 
> The header was then changed to make this "VectorDimension".
> 
> 
> It should be working now....
> are you testing this with a recent checkout ?
> 
> 
> As you said, it is easy to generalize the VectorInterpolator
> to accept any Array (actually FixedArray). It will be a matter
> of deciding how to name the Dimension.
> 
> Vector and CovariantVector derive both from FixedArray.
> 
> FixedArray calls its dimension "Length". We could add
> another enum ( / static int) to have a "Dimension"
> that could be used by the interpolator.
> 
> 
> BTW that will be quite helpful with a pending problem
> we have in the registration framework. Currently we
> cannot register RGB images. The first obstacle for
> this type of registration is the lack of interpolators
> that can act on RGBpixels. (the second obstacle is the
> lack of image metrics).
> 
> Conveniently RGBPixel<> already derives from FixedArray,
> so generalizing the VectorInterpolateImageFunction to
> accept FixedArrays will solve both problems.
> 
> 
> Does anybody see a possible conflict with these changes ?
> 
> 
>      Luis
> 
> 
> 
> =====================================================
> 
> Joshua Cates wrote:
> 
> > Hi,
> > 
> > There seems to be no way to use the VectorInterpolateImageFunction
> > subclasses with images of CovariantVectors (FixedArrays), i.e. the output 
> > of GradientImageFilter.  Does anyone have a workaround for this?
> > 
> > At first glance, looks like VectorInterpolateImageFunction could be
> > rewritten to accept any FixedArray, instead of limiting to just
> > itk::Vector.  It could then support itk::Vector and itk::CovariantVector.
> > 
> > Thanks,
> > 
> > Josh.
> > 
> > ______________________________
> >  Josh Cates			
> >  School of Computer Science	
> >  University of Utah
> >  Email: cates@sci.utah.edu
> >  Phone: (801) 587-7697
> >  URL:   www.cs.utk.edu/~cates
> > 
> > 
> > 
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> > 
> > 
> 
> 
>