[Insight-users] trouble using the bulktransform

[Erik Türke]

Luis Ibanez wrote:
> Hi Erik,
>
>
> Why are you using a static_cast in ?:
>
>
>   m_BSplineTransform->SetBulkTransform(
>       static_cast<VersorRigid3DTransformType*> (initialTransform));
>
>
> That static_cast should be necessary.
>
> ---
>
> I suspect that the problem is mostly related to
> the initialization of the BSpline Transform itself.
>
> Particularly related to the image Direction.
>
>
> You may want to use the following class:
>
>    Insight/Code/Review/
>        itkBSplineDeformableTransformInitializer.h
>        itkBSplineDeformableTransformInitializer.txx
>
>
> That is described in this Insight Journal paper:
>
>
> "Helper class for initializing the grid parameters of a
>  BSpline deformable transform by using an image as reference"
> http://www.insight-journal.org/browse/publication/216
> http://hdl.handle.net/1926/1338
>
>
> Note that is simply a complement to the use of the
> Bulk Transform, not a replacement for it.
>
>
>
>       Regards,
>
>
>
>             Luis
>
>
>
> -----------------------------------------------------------------------
> On Fri, Feb 26, 2010 at 10:42 AM, Erik Türke <tuerke at cbs.mpg.de> wrote:
>   
>> Hi!
>>
>> I am trying to use the SetBulkTransform method of the
>> BSplineDeformableTransform.
>>
>> The two images which i want to register are totally shifted, so i want to
>> use a simple translation as the bulk transform.
>>
>> So what  i am doing is:
>>
>> m_BSplineTransform->SetBulkTransform(static_cast<VersorRigid3DTransformType*>
>> (initialTransform));
>>
>> If i print out the parameters of the initialTransform with:
>>
>> std::cout << static_cast<VersorRigid3DTransformType*>
>> (initialTransform)->GetParameters() << std::endl;
>>
>> the output is: [0, 0, 0, 96.2941, 92.5804, 38.6559], what is totally right.
>>
>> Now i setup the BSplineTransform:
>>
>>               typedef typename BSplineTransformType::RegionType
>> BSplineRegionType;
>>               typedef typename BSplineTransformType::SpacingType
>> BSplineSpacingType;
>>               typedef typename BSplineTransformType::OriginType
>> BSplineOriginType;
>>               typedef typename BSplineTransformType::DirectionType
>> BSplineDirectionType;
>>
>>               BSplineRegionType bsplineRegion;
>>               typename BSplineRegionType::SizeType gridSizeOnImage;
>>               typename BSplineRegionType::SizeType gridBorderSize;
>>               typename BSplineRegionType::SizeType totalGridSize;
>>
>>               gridSizeOnImage.Fill(UserOptions.BSplineGridSize);
>>               gridBorderSize.Fill(3); //Border for spline order = 3 (1
>> lower, 2 upper)
>>               totalGridSize = gridSizeOnImage + gridBorderSize;
>>
>>               bsplineRegion.SetSize(totalGridSize);
>>               BSplineSpacingType bsplineSpacing =
>> m_FixedImage->GetSpacing();
>>
>>               BSplineOriginType bsplineOrigin = m_FixedImage->GetOrigin();
>>
>>               typename FixedImageType::SizeType fixedImageSize =
>> m_FixedImage->GetBufferedRegion().GetSize();
>>
>>               for (unsigned int r = 0; r < FixedImageDimension; r++) {
>>                   bsplineSpacing[r] *= static_cast<double>
>> (fixedImageSize[r] - 1) / static_cast<double> (gridSizeOnImage[r]
>>                           - 1);
>>               }
>>
>>               BSplineDirectionType bsplineDirection =
>> m_FixedImage->GetDirection();
>>               BSplineSpacingType gridOriginOffset = bsplineDirection *
>> bsplineSpacing;
>>
>>               bsplineOrigin = bsplineOrigin - gridOriginOffset;
>>
>>               m_BSplineTransform->SetGridSpacing(bsplineSpacing);
>>               m_BSplineTransform->SetGridOrigin(bsplineOrigin);
>>               m_BSplineTransform->SetGridRegion(bsplineRegion);
>>               m_BSplineTransform->SetGridDirection(bsplineDirection);
>>
>>               typedef typename BSplineTransformType::ParametersType
>> BSplineParametersType;
>>
>>               m_NumberOfParameters =
>> m_BSplineTransform->GetNumberOfParameters();
>>
>>               BSplineParametersType bsplineParameters(m_NumberOfParameters);
>>               bsplineParameters.Fill(0.0);
>>
>> m_BSplineTransform->SetParameters(bsplineParameters);
>>
>> m_RegistrationObject->SetInitialTransformParameters(m_BSplineTransform->GetParameters());
>>       If i now start the registration with 1 iteration, the result is
>> totally shifted again.
>> I am sure, the initial transform is right, because i got those values by
>> using the itk initializer class and tested the values as the initial
>> parameters of a VersorRigid3DTransform with iterations= 0 as well.
>> With the VersorRigid3DTransform, the images are aligned.
>> Why is the bulktransform not working here?
>>
>> I becoming a little desperate now :-( . Can somebody give me a hint?
>>
>> Thanks!
>>
>>
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>>     
Hi!

I was recognizing the same, when i browsed the examplecode.
But unfortunately that is not the source of trouble.

It is quiet odd, but tomorrow i will examine my code for the 10 th time :-)

Thanks anyway!