[Insight-users] Block match seg fault on different dimension images

[Matt McCormick]

Hi David,

Yes, there may be a bug somewhere in the boundary condition code or
the block matching code.

Thanks,
Matt

On Mon, Apr 15, 2013 at 7:39 PM, David Fuentes <fuentesdt at gmail.com> wrote:
> Thanks Matt,
>
> The default ZeroFluxNeumannBC that is used should not segfault when I access
> pixels outside the image ? correct ?
> When I run the block match, i'm expecting pixel access outside the image
> boundary to be taken care of by the Boundary condition class, but I'm
> getting seg faults?
> Is there some possible setup that I need for the ZeroFluxNeumanBC ?
>
>
> On Mon, Apr 15, 2013 at 9:18 AM, Matt McCormick <matt.mccormick at kitware.com>
> wrote:
>>
>> Hi David,
>>
>> It depends on the assumptions in the block-matching algorithm, and the
>> data, but ZorFluxNeumannBoundaryCondition is usually better than
>> ConstantBoundaryCondition.  For some datasets, like brain CT's,
>> ConstantBoundaryCondition is sufficient, but most other cases it is
>> not.
>>
>> Thanks,
>> Matt
>>
>> On Mon, Apr 15, 2013 at 3:07 AM, David Fuentes <fuentesdt at gmail.com>
>> wrote:
>> > Hi,
>> >
>> > The ZeroFluxNeumannBoundaryCondition that is being used by default for
>> > the
>> > ConstNeighborhoodIterator is causing seg faults on two images of
>> > different
>> > spacing and dimension for the BlockMatching filter. It is difficult to
>> > track
>> > down what is exactly causing the seg fault, but the
>> > ConstantBoundaryCondition seems to work.
>> >
>> > Is there any benefit of the  ZeroFluxNeumannBoundaryCondition ?
>> >
>> >
>> >
>> > index 2b6635b..5fb38a9 100644
>> > ---
>> > a/Modules/Registration/Common/include/itkBlockMatchingImageFilter.hxx
>> > +++
>> > b/Modules/Registration/Common/include/itkBlockMatchingImageFilter.hxx
>> > @@ -21,6 +21,7 @@
>> >  #include "itkBlockMatchingImageFilter.h"
>> >  #include "itkImageRegionConstIterator.h"
>> >  #include "itkConstNeighborhoodIterator.h"
>> > +#include "itkConstantBoundaryCondition.h"
>> >  #include <limits>
>> >
>> >
>> > @@ -314,10 +315,12 @@ BlockMatchingImageFilter< TFixedImage,
>> > TMovingImage,
>> > TFeatures, TDisplacements,
>> >      center.SetIndex( movingIndex );
>> >
>> >      // iterate over neighborhoods in region window, for each
>> > neighborhood:
>> > iterate over voxels in blockRadius
>> > -    ConstNeighborhoodIterator< FixedImageType > windowIterator(
>> > m_BlockRadius, fixedImage, window );
>> > +    typedef itk::ConstantBoundaryCondition<FixedImageType>
>> > FixedBoundaryConditionType;
>> > +    ConstNeighborhoodIterator<
>> > FixedImageType,FixedBoundaryConditionType >
>> > windowIterator( m_BlockRadius, fixedImage, window );
>> >
>> >      // iterate over voxels in neighborhood of current feature point
>> > -    ConstNeighborhoodIterator< MovingImageType > centerIterator(
>> > m_BlockRadius, movingImage, center );
>> > +    typedef itk::ConstantBoundaryCondition<MovingImageType>
>> > MovingBoundaryConditionType;
>> > +    ConstNeighborhoodIterator<
>> > MovingImageType,MovingBoundaryConditionType
>> >> centerIterator( m_BlockRadius, movingImage, center );
>> >      centerIterator.GoToBegin();
>> >
>> >
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>