[Insight-users] BSplineDeformableTransform + Alternatve way to change coefficients

[Luis Ibanez]

Hi Kaveh,

Your description of what you want to do wasn't very clear.

Are you trying to initialize a deformation field ?


At first sight it seems that what you are looking for  is a
functionality provided by the method:

                    SetBulkTransform()

that inserts a pre-transform to the deformation produced
by the BSpline.



       Regards,


              Luis

On Mon, Mar 8, 2010 at 1:21 PM, Kaveh Kohan <kaveh.kohan at yahoo.com> wrote:
> Hi All,
>
> I have a question about one of functions of itk::BSplineDeformableTransform
> and I would be thankful if somebody answers:
>
> I would like to simulate some deformation fields by changing the identity
> transformation locally. I thought that perhaps BSpline model is a good
> candidate but I don't know how to use  "SetCoefficientImages"  function. It
> seems that if I want to know which part of image is perturbed from identity
> map this is a good option because using parameter type is very implicit.
> Here is how I tried but apparently it is not correct:
>
> [...]
> typedef itk::BSplineDeformableTransform< double,
>                                            Dimension,
>                                            3 >     BSplineTransformType;
>
>     BSplineTransformType::Pointer bsplineTransform =
> BSplineTransformType::New();
>
>
>     typedef BSplineTransformType::RegionType RegionType;
>     RegionType bsplineRegion;
>     RegionType::SizeType   gridSizeOnImage;
>     RegionType::SizeType   gridBorderSize;
>     RegionType::SizeType   totalGridSize;
>
>     gridSizeOnImage.Fill( 8 );
>     gridBorderSize.Fill( 3 );
>     totalGridSize = gridSizeOnImage + gridBorderSize;
>
>     bsplineRegion.SetSize( totalGridSize );
>
>     typedef BSplineTransformType::SpacingType SpacingType;
>     SpacingType bsplineSpacing = reader->GetOutput()->GetSpacing();
>
>     typedef BSplineTransformType::OriginType OriginType;
>     OriginType bsplineOrigin = reader->GetOutput()->GetOrigin();;
>
>     InputImageType::SizeType ImageSize =
> reader->GetOutput()->GetLargestPossibleRegion().GetSize();
>
>     for(unsigned int r=0; r<Dimension; r++)
>     {
>       bsplineSpacing[r] *= floor( static_cast<double>(ImageSize[r] )  /
>           static_cast<double>(gridSizeOnImage[r] ) );
>       bsplineOrigin[r]  -=  bsplineSpacing[r];
>     }
>
>     bsplineTransform->SetGridSpacing( bsplineSpacing );
>     bsplineTransform->SetGridOrigin( bsplineOrigin );
>     bsplineTransform->SetGridRegion( bsplineRegion );
>
>
>     typedef BSplineTransformType::ImageType          ParamImageType ;
>
>
>     ParamImageType::Pointer  bsplineImageParameters[3] ;
>
> [...]
>
> then I don't know what to do next! should I go ahead and define image
> size,origin.direction and then allocate memory for each
> bsplineImageParameters[0,1,2] but I have already specified grid size! how do
> they relate?  I am confused how to use it.
>
> Any comment is highly appreciated.
>
> Regards,
> kaveh
>
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