[Insight-developers] ConditionalConstIterator Error?

[Luis Ibanez]

Hi John,


It is not a problem that the path does not cover all
the image. In fact, most iterator don't cove the full
image since they are conditioned to walk over a region.

You can safely derive your new iterator from the
ImageConstIterator (or the ImageConstIteratorWithIndex).

There is no advantage in deriving from the
ConditionalConstIterator. As a matter of fact you just
encountered that the conditional iterator has additional
functionality that is not needed in your path iterator.


Please note also that Josh recently added a chapter on
iterators to the SoftwareGuide.pdf.

Hope that helps


    Luis


--------------------------------------
John M. Galeotti wrote:
> Hello, I am working on an iterator to walk through an image following 
> any type of path.  Since most paths will not cover all image indices, it 
> would be logical for this iterator to descend from 
> ConditionalConstIterator, but there is one small problem.  
> ConditionalConstIterator includes the pure virtual function 
> IsPixelIncluded(), which would be almost useless and prohibitively 
> expensive to calculate for some types of paths (paths are almost always 
> traveled linearly), and so I really do not want to implement the 
> exhaustive search required for it.  The documentation in 
> ConditionalConstIterator states that this function is used to "Compute 
> whether the index of interest should be included in the flood."  
> Therefore, it seems that this pure virtual function should be introduced 
> into the ITK class hierarchy in its child 
> FloodFilledFunctionConditionalConstIterator, not in 
> ConditionalConstIterator.  A quick look at the ConditionalConstIterator 
> inheritance diagram seems to indicate that this would not be a problem, 
> and FloodFilledFunctionConditionalConstIterator.h would not even have to 
> be modified.
> 
> Could someone please remove the IsPixelIncluded() function from 
> ConditionalConstIterator.h?
> 
> Thank you,
> John Galeotti
> jgaleotti@cmu.edu
> 
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