[Insight-developers] writing an ImageToImageFilter, problem with Requested Region...

[kent williams]

This sort of makes sense, but what I¹m trying to do is fix my filter so it
can be called twice on different sized inputs.  Is it the responsibility of
users to know when they should call UpdateLargestPossibleRegion instead of
Update?



On 7/24/09 2:58 PM, "Bradley Lowekamp" <blowekamp at mail.nih.gov> wrote:

> Hello Kent,
> 
> This sounds familiar. If I recall correctly try calling:
> 
> x->UpdateLargestPossibleRegion();
>  
> instead of:
> 
> x->Update();
> 
> I think it comes down to an old RequestedRegion sticking around in the output
> image of the filter.
> 
> Brad
> 
> 
> On Jul 24, 2009, at 3:44 PM, kent williams wrote:
> 
>> I've been working on an ITK filter that encapsulates some processing
>> previously done in an ad hoc function -- the idea being we'd like to be able
>> to stick it in a pipeline, rather than run one pipeline, call the function,
>> and run the rest of the pipeline.
>> 
>> The filter as I've written it works fine.  But if I try and re-use the
>> filter it throws an exception:
>> 
>> terminate called after throwing an instance of
>> 'itk::InvalidRequestedRegionError'
>>   what():  
>> /scratch/kent/BT/BRAINS-COMPILE/Darwin/DEBUG_64-lib/Insight/Code/Common/itkD
>> ataObject.cxx:397:
>> Requested region is (at least partially) outside the largest possible
>> region.
>> 
>> In other words what I'm doing is this:
>> 
>>     itk::MyFilter::Pointer x = itk::MyFilter::New();
>>     x->SetInput(inputImage1);
>>     x->Update();
>>     firstresult = x->GetOutput();
>>     x->SetInput(inputImage2);
>>     x->Update();  // *** EXCEPTION HERE
>>     secondresult = x->GetOutput();
>> 
>> The problem happens in itk::DataObject::PropogateRequestedRegion, because
>> VerifyRequestedRegion() fails -- the requested region is based on the size
>> of inputImage1. inputImage2 has a smaller volume, so it can't satisfy the
>> larger RequestedRegion.
>> 
>> So the question is this:  What should I be doing in my filter to support
>> re-use?  How am I supposed to make the filter re-compute the requested
>> region based on the size of the new Input?
>> 
>> Or I guess another question might be this: Do ITK Filters, in general, ever
>> support this kind of re-use?
>> 
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> 
>  
> ========================================================
> 
> Bradley Lowekamp 
> 
> Lockheed Martin Contractor for
> 
> Office of High Performance Computing and Communications
> 
> National Library of Medicine
> 
> blowekamp at mail.nih.gov
> 
>  
> 
> 

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