[Insight-users] DisplacementFieldToBSplineImageFilter

[Emma Saunders]

Hi Nick / all,

Thanks for your recent input w.r.t using a Confidence Image with
the  itk::DisplacementFieldToBSplineImageFilter.  I am attempting to use it
by creating my own confidence image via:

           typedef float PixelType;
  typedef itk::Image< PixelType, 3 >          ImageType;
  ImageType::Pointer ConfidenceImage = ImageType::New();


And applying appropriate size, index values etc.

and applying via Bspline->SetConfidenceImage(ConfidenceImage)

However an error I receive is "no matching function to:
:SetConfidenceImage(itk::SmartPointer<itk::Image<float, 3u> >&)’"


Output mentions using ::SetConfidenceImage(const itk::Image<typename
TOutputImage::PixelType::RealValueType,
itk::DisplacementFieldToBSplineImageFilter<TInputImage,
TOutputImage>::ImageDimension>*)

Does this require I use a const image, if so I'm having trouble with
defining such could someone point me in the right direction of how to
create a const image as I can only find documentation w.r.t smartpointer
images, or is there something that I have done wrong w.r.t the filter??

Advice appreciated

Emma





On Wed, Apr 17, 2013 at 4:37 PM, Nick Tustison <ntustison at gmail.com> wrote:

> Hi Emma,
>
> Please keep the conversation on the email list as others
> might have similar questions.
>
> You're getting expected behavior based on what you're
> telling me.  I assume your sparse displacement field is
> actually a "dense" displacement field with sparse non-zero
> entries (at least that's the way the filter sees it).  Fortunately,
> there's an easy work-around.  I put an option in the filter to
> specify a confidence image which can be used to spatially
> vary the weighting of individual displacement vectors.
>
> filter->SetConfidenceImage( confidenceImage );
>
> So, in your case, you would define the confidence image as an
> image with a non-zero constant value (let's say '1' since only
> the relative weighting matters) at the voxels that have non-zero
> displacements.  THat should give you what you need.
>
> Nick
>
>
>
>
> The filter is treating your zer
>
> On Apr 17, 2013, at 11:16 AM, Emma Saunders <emmasaunders123 at gmail.com>
> wrote:
>
> Hi Nick,
>
> Thanks for pointing me in the correct direction of the test.
>
> I am new to ITK, would you kindly offer some advice
> w.r.t itkDisplacementFieldToBSplineImageFilter.h
>
> I have as input to this filter a sparse vector field, 5, 2D slices, each
> slice is spaced 20 voxels apart, I would like a dense approximation of this
> field and was under the impression this filter could do that, i.e
> interpolate between the slices
>
> When I run the filter however and use bspliner->GetDisplacementField()
> what returns is something similar to the original, i.e the gaps inbetween
> are not filled in or interpolated.  I have left the spline order at 3,
> fitting levels at 5 and control points at 4,
>
> Would you be-able to clarify that my expectation of this filter are
> correct or offer any other alternatives for vector field interpolation?
>
> Kind regards
>
> Emma
>
>
> On Tue, Apr 16, 2013 at 8:31 PM, Nick Tustison <ntustison at gmail.com>wrote:
>
>> Did you look at the test?
>>
>>
>> ITK/Modules/Filtering/DisplacementField/test/itkDisplacementFieldToBSplineImageFilterTest.cxx
>>
>>
>>
>> On Apr 16, 2013, at 2:47 PM, Emma Saunders <emmasaunders123 at gmail.com>
>> wrote:
>>
>> > Hi all,
>> >
>> > could anyone point me towards a working example which utilizes:
>> >
>> > DisplacementFieldToBSplineImageFilter
>> >
>> > Kind regards
>> >
>> > Emma
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