[Insight-users] forcing pipeline to update

[Jakub Bican]

Hello,

i have a short pipeline - two filters: ResampleImageFilter followed by 
FFTWRealToComplexConjugateImageFilter.

I am using it to compute different transforms of the same data:

1) connect the pipeline, set input to the resample filter
2) loop:
     A) change the transform in resample filter according to the loop 
variable i
     B) set up the output parameters of resmaple filter 
(origin,spacing,size)
     C) UpdateLargestPossibleRegion() of resample filter
     D) UpdateLargestPossibleRegion() of fourier filter
     E) store the transformed data and disconnect it:
             transformedData[i] = fourierFilter->GetOutput();
             transformedData[i]->DisconnectPipeline();
3) end loop

* step C is neccessary due to some bug in fourier filter that i reported 
some weeks ago (otherwise fourier filter fails)
* step B is not usually neccessary - but sometimes i use different 
parameters for each transformed version

The problem is, that if the parameters of the resample filter do not 
change in step B, then step C does not process anything and immediately 
terminates without having updated resample filter's output.

I suppose this behavior is expectable, because resample filter has no 
reason to update its output ("input and any parameters else than 
something inside of the transform did not change"), but i need to force 
it to compute.

The only solution i thought of is resetting and reconnecting the 
pipeline, but i don't like it very much. Please, if anyone knows any 
clear solution how to force the filter or pipeline to update even if it 
is up-to-date, let me know.

Thank you very much in advance.

Cheers,
                 Jakub