[Insight-users] Writing BSpline transform with itkTransformFileWriter

[Albert Gubern]

Hi,

I am having troubles writing a BSpline transform produced by
DeformableRegistration15.cxx example. I have implemented a
bsplineRegistration method, based on that example, that returns the final
transform. From my main program, I apply the transform to the image and
observing the transformed image I can see that the transform has been
applied successfully. At the same time, I write the transform using the
itkTransformFileWriter but the parameters field of the produced file is
empty. Here is an example:

****************************************
#Insight Transform File V1.0
# Transform 0
Transform: BSplineDeformableTransform_double_3_3
Parameters:
FixedParameters: 11 11 11 -73 -17 -36.4286 73 17 36.4286 1 0 0 0 1 0 0 0 1
***************************************

And the code to write the transform is as follows:


****************************************
    itk::TransformFileWriter::Pointer writerTransform;
    writerTransform = itk::TransformFileWriter::New();

    writerTransform->AddTransform(transform);
    writerTransform->SetFileName(filename.c_str());

    try{
        writerTransform->Update();
    }
    catch( itk::ExceptionObject & excp )
    {
        std::cerr << "Exception thrown INPUT_OUTPUT TransformWriter" <<
std::endl;
        std::cerr << excp << std::endl;
        return EXIT_FAILURE;
    }
**********************************


I have noticed of this problem when I have tried to read the transform file
and I got the following error:

*******************************************************
Loading Transform: .../Transforms/2_3.txt
terminate called after throwing an instance of 'itk::ExceptionObject'
  what():
 /usr/local/include/InsightToolkit/Common/itkBSplineDeformableTransform.txx:510:
itk::ERROR: BSplineDeformableTransform(0x100bb9bf0): Mismatched between
parameters size 0 and region size 1331
******************************************************

And the program produces the error when is executing the Update() of the
next lines:

**************************************************
typedef itk::TransformFileReader  TransformReaderType;
TransformReaderType::Pointer transformReader = TransformReaderType::New();

std::cout << "Loading Transform: " << filename << std::endl;
transformReader->SetFileName( filename.c_str());
transformReader->Update();
**************************************************


Finally comment that same code has been tested with Affine transform and I
have not had problems reading, writing and using the Affine transform.

Any idea about what I am doing wrong?


Thanks in advance.

-- 
Albert
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