[Insight-users] Re: [Insight-developers] question about adding a user-defined transformation (for registration)

[Luis Ibanez]

Hi Dan,

Please look at the header file:

    Insight/Code/Common/itkTranslationTransform.txx

http://www.itk.org/cgi-bin/viewcvs.cgi/Code/Common/itkTranslationTransform.txx?annotate=1.30&root=Insight


You will find the following code


A) TransformPoint() method in lines 123-132:

// Transform a point
template<class TScalarType, unsigned int NDimensions>
typename TranslationTransform<TScalarType, NDimensions>::OutputPointType
TranslationTransform<TScalarType, NDimensions>::
TransformPoint(const InputPointType &point) const
{
   return point + m_Offset;
}



B) GetJacobian() method in lines 179- 193

// Compute the Jacobian in one position
template<class TScalarType, unsigned int NDimensions>
const typename TranslationTransform<TScalarType, 
NDimensions>::JacobianType &
TranslationTransform< TScalarType, NDimensions >::
GetJacobian( const InputPointType & ) const
{

   this->m_Jacobian.Fill( 0.0 );

   for(unsigned int i=0; i<NDimensions; i++)
     {
     this->m_Jacobian(i,i) = 1.0;
     }

   return this->m_Jacobian;

}



These are the lines in the current CVS version of ITK.
They may look slightly different if you are using an
older version.



Regards,


     Luis



-----------------------
Dan Koppel wrote:
> Hi Luis,
>   I am trying to follow your advice to rewrite the TransformPoint() and 
> GetJacobian() functions contained in the class TranslationTransform.  I 
> am looking at the file itkTranslationTransform.txx which is the only one 
> that I can see defining the TranslationTransform class.  Perhaps this is 
> the wrong file, I don't know.  However, the 2 functions you mention are 
> not defined here.  Could you please tell me which file would be the 
> correct one to modify?
>  
> Thanks very much,
>   Dan
> 
> */Luis Ibanez <luis.ibanez at kitware.com>/* wrote:
> 
> 
>     Hi Dan,
> 
> 
>     Welcome to ITK !
> 
> 
>     --
> 
>     If you are asking for the procedure for contributing new
>     classes to ITK, please read the following Wiki page:
>     http://www.itk.org/Wiki/ITK_Procedure_for_Contributing_New_Classes_and_Algorithms
> 
> 
>     If you are asking about how to write your own customized
>     Transform, then the easy way is indeed to start by following
>     the model of the Translation transform and to only implement
>     the TransformPoint() method.
> 
>     At that level you will be able to use the Transform with optimizers
>     that do not require Derivatives of the CostFunction (Image Metric).
>     (for example OnePlusOneEvolutionaryOptimizer and AmoebaOptimizer).
> 
>     Once you get that to work, you can add the GetJacobian() method.
>     That method will make possible for your Transform to be used with
>     optimizers that require cost function derivatives.
> 
> 
>     Please let us know if you run into specific problems
>     when writing your new Transform.
> 
> 
> 
>     Thanks
> 
> 
>     Luis
> 
> 
> 
>     -------------------
>     Dan Koppel wrote:
>      > Hello All,
>      > I am new to ITK and am interested in adding my own (user-defined)
>      > transformation for use in registering images. I am looking at the
>     file
>      > "itkTranslationTransform.txx" for guidance. However, it seems fairly
>      > involved. Can anybody tell me what the standard procedure (if
>     any) is
>      > for including new user-defined registration transformations (ie.
>     image
>      > warping)?
>      >
>      > Thanks in advance,
>      > Dan
>      >
>      >
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