[Insight-users] Trouble using the TileImageFilter

[Luis Ibanez]

Hi Erik,

The TileImageFilter expects you to provide a set of different
Image pointers to the method:

               tileImageFilter->PushBackInput(   );

However, you are always calling this method with the argument:

                    resampler->GetOutput());

Since a filter owns its output, the resampler filter is providing the
same image pointer every time.

One possible solution here, is for you to disconnect the output
of the resample filter before you connect it as input to the Tile
filter. In this way the resample filter has to allocate a new image
from scratch, and therefore it will provide a different image pointer
every time.

In sumary:

Replace the line:

    tileImageFilter->PushBackInput(  resampler->GetOutput()   );

with the lines

   OutputImageType::ConstPointer tileImage =
           resampler->GetOutput();

   tileImage->DisconnectPipeline();

    tileImageFilter->PushBackInput( tileImage   );


BTW:
It is good that you are already calling "resampler->Update()"
before you attempt to use resampler->GetOutput().
This is important, since it guarantees that the output image
is computed.


      Regards,


            Luis


-----------------------------------------------------------------------------------------
On Wed, Oct 28, 2009 at 1:28 PM, Erik Tuerke <tuerke at cbs.mpg.de> wrote:
> Hi!
>
> I have some trouble using the itk::TileImageFilter. :-(
>
> What i want to do is creating an 4d image with the help of this filter.
>
> Here is my approach:
>
> const unsigned int Dimension = 3;
> const unsigned int fmriDimension = 4;
>
> typedef itk::Image<PixelType, Dimension> OutputImageType;
> typedef itk::Image<PixelType, fmriDimension> FMRIOutputType;
>
> typedef itk::ImageFileWriter<FMRIOutputType> FMRIImageWriterType;
>
> typedef itk::TileImageFilter<OutputImageType, FMRIOutputType>
> TileImageFitlerType;
>
> FMRIImageWriterType::Pointer fmriWriter = FMRIImageWriterType::New();
> TileImageFitlerType::Pointer tileImageFilter = TileImageFitlerType::New();
>
> itk::FixedArray<unsigned int, 4> layout;
> layout[0] = 1;
> layout[1] = 1;
> layout[2] = 1;
> layout[3] = 0;
> tileImageFilter->SetLayout(layout);
>
> for(unsigned int timestep = 0; timestep < numberOfTimeSteps; timestep++) {
>       std::cout << "Resampling timestep: " << timestep << "...\r" <<
> std::flush;
>       timeStepExtractionFilter->SetRequestedTimeStep(timestep);
>       timeStepExtractionFilter->Update();
>       resampler->SetInput(timeStepExtractionFilter->GetOutput());
>       resampler->Update();
>
>       //here it would be possible to save each image obtained from the
> resampler. I have tested that...so this should not be the source of error
>
>       tileImageFilter->PushBackInput(resampler->GetOutput());
> }
> tileImageFilter->Update();
> fmriWriter->SetInput(tileImageFilter->GetOutput());
> fmriWriter->Update();
>
>
> What  i am getting is a 4d image with dimension[3] = numberOfTimeSteps...as
> expected.
>
> The problem is, that each timestep shows the same image (the last one).
>
> Has someone an idea what i am doing wrong here ??
>
> Thanks for yout help!!
>
>
>
>
>
>
>
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