[Insight-users] ShapedNeighborhoodIterator + SetNeedToUseBoundaryCondition

[Bill Lorensen]

Brady,

Please enter your request into the itk bug tracker following the
procedure described here:
http://itk.org/Wiki/ITK_Procedure_for_Contributing_Bug_Fixes

Bill

On Tue, Jan 19, 2010 at 5:43 PM, Brady McCary
<brady.mccary+ITK at gmail.com> wrote:
> insight-users,
>
> In my local ITK repository I have added the necessary line in
> ConstShapedNeighborhoodIterator to export
> NeighborhoodIterator::SetNeedToUseBoundaryCondition. The reason why I have
> done this is because I am performing a computation using a
> ShapedNeighborhoodIterator and it is possible for me to tell whether or not
> I will need a boundary condition.
>
> In the normal case, a NeighborhoodIterator determines whether or not it
> needs a boundary condition by comparing the image region with the iteration
> region. If the iteration region touches the edges of the image region
> (padded by the neighborhood radius), the iterator thinks it will need a
> boundary condition. In the case of dense iteration over the whole image, the
> usual approach is to break the image into one big piece that does not need a
> boundary condition and other small peices that do.
>
> However, in a non-dense iteration over the entire image region, it may be
> possible for a filter to tell that a boundary condition will never be
> needed. For this case, we have
> NeighborhoodIterator::SetNeedToUseBoundaryCondition. An optimization like
> this is used in the sparse-field level set solver.
>
> I have considered the code for ConstNeighborhoodIterator and
> ConstShapedNeighborhoodIterator and I see no reason why
> SetNeedToUseBoundaryCondition is not exported. I have used a shaped iterator
> with boundary condition explicitly turned off for many different simulations
> and have seen no problem or artifact.
>
> For these reasons, I would recommend that
> NeighborhoodIterator::SetNeedToUseBoundaryCondition and friends be exported
> in ConstShapedNeighborhoodIterator.
>
> Brady
>
> On Mon, Jan 18, 2010 at 4:33 PM, Brady McCary <brady.mccary+ITK at gmail.com>
> wrote:
>>
>> insight-users,
>>
>> ShapedNeighborhoodIterator is a subclass of NeighborhoodIterator. Is there
>> a reason why NeighborhoodIterator::SetNeedToUseBoundaryCondtion is not
>> exported in ShapedNeighborhoodIterator?
>>
>> Brady
>
>
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