[Insight-users] DisplacementFieldToBSplineImageFilter

Thu Apr 18 13:47:42 EDT 2013

Hi thanks for the response,

what I needed however was to define the image as:

 typedef BSplineFilterType::RealImageType
 RealImageType;

  RealImageType::Pointer confidenceImage = RealImageType::New();

However I still have my previous problem where no interpolation seems to
be performed on the output, any suggestions appreciated

also bspline->GetDisplacementField() is a type ‘const
itk::Image<itk::Vector<double, 3u>, 3u>*

How can I convert this to a  ‘itk::Image<itk::Vector<double, 3u>, 3u>*’

 such that outfield-=bspline->GetDisplacementField() is of type
displacementfieldtype

         typedef itk::Vector< double, Dimension >
VectorPixelType;
 typedef itk::Image<VectorPixelType, Dimension>   DisplacementFieldType;

I currently write the output which seems to work but cant create an
instance of it as outfield,

Help appreciated

Thanks

On Thu, Apr 18, 2013 at 2:44 PM, Karthik Krishnan <
karthik.krishnan at kitware.com> wrote:

> RealValueType would mean an image with a datatype of 'double' and not
> 'float' as you have instantiated.
>
> HTH
>
>
> On Thu, Apr 18, 2013 at 6:05 PM, Emma Saunders <emmasaunders123 at gmail.com>wrote:
>
>> 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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>>>>
>>>
>>>
>>
>> _____________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Kitware offers ITK Training Courses, for more information visit:
>> http://www.kitware.com/products/protraining.php
>>
>> Please keep messages on-topic and check the ITK FAQ at:
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>>
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>
>
> --
> karthik
>
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