[Insight-developers] Changing ImageRegionMultidimensionalSplitter

[Bradley Lowekamp]

Hello,


	As shown in the failing test code:

http://public.kitware.com/cgi-bin/viewcvs.cgi/Testing/Code/BasicFilters/itkStreamingImageFilterTest3.cxx?revision=1.1&root=Insight&view=markup

This is a typical usage for this splitter. It is only used when  
explicitly set  for the itkStreamingImageFilter. This splitting policy  
is not used by default any place.

I have completed the revised multi-dimensional splitting algorithm. It  
solves all the issues with the current methodology, and the all the  
tests pass. I will post it as a patch to the related Matis bug, and  
comment out these test so that they will not be run.

Brad

On Aug 15, 2009, at 12:55 PM, Bill Lorensen wrote:

> Eventually, we could add alternate splitting policies, keeping the
> current one as a default. For now, I agree that the documentation
> should be fixed.
>
> And, we need to get the failing tests to pass. They are hiding other  
> failures.
>
> Bill
>
> On Sat, Aug 15, 2009 at 12:52 PM, Luis  
> Ibanez<luis.ibanez at kitware.com> wrote:
>> I would vote for
>>
>> a)  fixing the documentation. (which is backward compatible), and
>>
>> b) if we need an alternative splitting algorithm:
>>     then refactor this  in ITK 4.0.
>>
>>
>> My 2 cents,
>>
>>
>>      Luis
>>
>>
>> --------------------------------------------------------------------------------
>>
>> On Wed, Aug 12, 2009 at 10:12 AM, Bradley Lowekamp <blowekamp at mail.nih.gov 
>> >
>> wrote:
>>>
>>> Hello,
>>> I am looking for agreement that this will be a good solution, with
>>> acceptable backwards compatibility.
>>> Looking into the following bug:
>>> http://www.itk.org/Bug/view.php?id=8524
>>> I discovered the methods do not meet the documentation. And that the
>>> general approach to multi-dimensional splitting can not meet the
>>> requirements of the documentation. This class is designed to work  
>>> with the
>>> StreamingImageFilter, and is currently not functional under many  
>>> conditions.
>>> To illustrate one of the problem consider the case where the  
>>> Region to be
>>> split is [100,100,1] and the requested number of splits is 100:
>>>
>>> http://www.cdash.org/CDash/viewCoverageFile.php?buildid=400312&fileid=10857899
>>> When the number of splits is reduced we will not get the same  
>>> number of
>>> splits for the two methods. These are the lines not covered.
>>>
>>>   /** How many pieces can the specifed region be split? A given  
>>> region
>>>    * cannot always be divided into the requested number of  
>>> pieces.  For
>>>    * instance, if the numberOfPieces exceeds the number of pixels  
>>> along
>>>    * a certain dimensions, then some splits will not be possible.  
>>> This
>>>    * method returns a number less than or equal to the requested  
>>> number
>>>    * of pieces.  */
>>>   virtual unsigned int GetNumberOfSplits(const RegionType &region,
>>>                                          unsigned int  
>>> requestedNumber);
>>>   /** Get a region definition that represents the ith piece a  
>>> specified
>>> region.
>>>    * The "numberOfPieces" specified should be less than or equal  
>>> to what
>>>    * GetNumberOfSplits() returns. */
>>>   virtual RegionType GetSplit(unsigned int i, unsigned int  
>>> numberOfPieces,
>>>                               const RegionType &region);
>>>
>>> -Proposed Solution-
>>> 1) Change Documentation
>>>   /** Get a region definition that represents the ith piece a  
>>> specified
>>> region.
>>>    * The "numberOfPieces" specified must be equal to what
>>>    * GetNumberOfSplits() returns. */
>>>   virtual RegionType GetSplit(unsigned int i, unsigned int  
>>> numberOfPieces,
>>>                               const RegionType &region);
>>> 2) New algorithm for Multi-dimensional splitting
>>> Instead of taking the nth root and shrinking the splits in each  
>>> dimension,
>>> the new approach will be:
>>> iteratively split the dimension who's splitted region is the  
>>> largest. This
>>> will be reproducible between the two methods.
>>>
>>> Any problems with this solution?
>>> Thanks,
>>> Brad
>>>
>>> ========================================================
>>>
>>> Bradley Lowekamp
>>>
>>> Lockheed Martin Contractor for
>>>
>>> Office of High Performance Computing and Communications
>>>
>>> National Library of Medicine
>>>
>>> blowekamp at mail.nih.gov
>>>
>>>
>>> _______________________________________________
>>> Powered by www.kitware.com
>>>
>>> Visit other Kitware open-source projects at
>>> http://www.kitware.com/opensource/opensource.html
>>>
>>> Please keep messages on-topic and check the ITK FAQ at:
>>> http://www.itk.org/Wiki/ITK_FAQ
>>>
>>> Follow this link to subscribe/unsubscribe:
>>> http://www.itk.org/mailman/listinfo/insight-developers
>>>
>>
>>
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Please keep messages on-topic and check the ITK FAQ at:
>> http://www.itk.org/Wiki/ITK_FAQ
>>
>> Follow this link to subscribe/unsubscribe:
>> http://www.itk.org/mailman/listinfo/insight-developers
>>
>>