[Insight-developers] [Insight-users] LevelsetMotionRegistrationImageFilter

[Luis Ibanez]

Hi Kishore,

Thanks for pointing this out,
and for filing the bug report.

Unfortunately this class don't even have a test.
So, we have started by adding a test for it,
(mostly based on the test of the Demons filter).

You will find this new test under:

Insight/Testing/Code/Algorithms/
               itkLevelSetMotionRegistrationFilterTest.cxx


This test is running the filter with the method

           UseImageSpacingOn()

and we don't observe a segmentation fault as a
consequence.

.....

In your email you say that the member variable

                    this->m_Input,

>> is a vector of 3 image pointers.


For what I can see in this filter, the Input variable
is actually of the same type as the InputImage
type used for instantiating the filter.


Could you provide a minimal example illustrating
the situation in which you see that the m_Input
variable is an array of images  ?


     Thanks


           Luis


-----------------------------------------------------------
On Tue, Oct 13, 2009 at 7:36 PM, Kishore Mosaliganti
<kishoreraom at gmail.com> wrote:
> To add to the below problem, I initialized the filter with a 0 vector
> deformation field. Now, the filter executes with ImageSpacingOn().
> However, the metric values with iterations are not influenced by the
> ImageSpacingOn option.
>
> This makes me believe the underlying implementation is not using the
> image spacings.
>
> Kishore
>
> On Tue, Oct 13, 2009 at 7:13 PM, Kishore Mosaliganti
> <kishoreraom at gmail.com> wrote:
>> Hi all,
>>
>> I was using the LevelsetMotionRegistrationImageFilter to register two
>> 3D image datasets whose voxels have anisotropic spacing:
>>
>>  RegistrationFilterType::Pointer filter = RegistrationFilterType::New();
>>  CommandIterationUpdate::Pointer observer = CommandIterationUpdate::New();
>>  filter->AddObserver( itk::IterationEvent(), observer );
>>  filter->SetFixedImage( fixedImage );
>>  filter->SetMovingImage( movingImage );
>>  filter->SetNumberOfIterations( 50 );
>>  filter->SetGradientSmoothingStandardDeviations( 0.1 );
>>  filter->UseImageSpacingOn();
>>  filter->Update();
>>
>> The problem is I get a Segmentation fault when I turn on
>> UseImageSpacingOn(). Otherwise, the filter executes normally.
>>
>> I used the debugger and went into the code.
>> LevelsetMotionRegistrationImageFilter is a sub-class of
>> PDEDeformableRegistrationImageFilter which is a subclass of
>> FiniteDifferenceImageFilter. The code failed in the
>> FiniteDifferenceImageFilter::GenerateData() method in the following
>> lines:
>>
>> ....
>>
>> if (this->GetState() == UNINITIALIZED)
>>    {
>>    // Set the coefficients for the deriviatives
>>    double coeffs[TInputImage::ImageDimension];
>>    if (m_UseImageSpacing)
>>      {
>>      for (unsigned int i = 0; i < TInputImage::ImageDimension; i++)
>>        {
>>        coeffs[i] = 1.0 / this->GetInput()->GetSpacing()[i];
>>        }
>>      }
>>    else
>>      {
>>      for (unsigned int i = 0; i < TInputImage::ImageDimension; i++)
>>        {
>>        coeffs[i] = 1.0;
>>        }
>>      }
>>
>> .....
>>
>> When I went to see the state of the input pointer, this->m_Input, it
>> is a vector of 3 image pointers. Basically, this->m_Input[1] refers to
>> the fixed image and this->m_Input[2] refers to the moving image.
>> this->m_Input[0] is NULL. this->m_Input[0] is supposed to contain the
>> initial deformation field which is not a prerequisite for running the
>> code.
>>
>> The code in itkPDEDeformableRegistrationImageFilter::SetFixedImage()
>> and itkPDEDeformableRegistrationImageFilter::SetMovingImage() call
>> this->ProcessObject::SetNthInput( 1, const_cast< FixedImageType * >(
>> ptr ) ) and this->ProcessObject::SetNthInput( 2, const_cast<
>> FixedImageType * >( ptr ) ) respectively.
>>
>> This filter derives from
>> ImageToImageFilter<TDeformationField,TDeformationField> but the vector
>> of inputs have been set as scalar-valued fixed and moving image
>> pointers. Also, for the case when the initial deformation field is
>> unknown, the FiniteDifferenceFilter is checking for the first input
>> which doesn't exist.
>>
>> I have filed a bug report:
>> http://public.kitware.com/Bug/view.php?id=9709
>>
>>
>>
>> Thanks,
>> Kishore
>>
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