[ITK-users] QVtkWidget beginner questions

[Matt McCormick]

Hi Ibraheem,

On Thu, Sep 1, 2016 at 4:20 AM, Ibraheem via Insight-users
<insight-users at itk.org> wrote:
> Many thanks Matt for your response and answers.
>
> Matt McCormick-3 wrote
>>>   1- Is there a way to filter and write all the images at once instead of
>>> using the for loop?
>> To write to an image series in general, there is an
>> itk::ImageSeriesWriter.
>
> I tried this:
>           reader->SetFileNames(inputNames->GetInputFileNames() ); // get all
> slices
>           reader->Update();
>           // filtering : get threshold
>           filterThresh->SetInput( reader->GetOutput() );
>           QString thVals=ui->ThVal->text();
>           int ut= thVals.toInt() ;
>           filterThresh->ThresholdAbove(ut);
>           filterThresh->SetOutsideValue(0);
>           filterThresh->Update();
>           // Convert to VTK image using ImageToVTKImageFilter
>            vtkImgF->SetInput(filterThresh->GetOutput (sliceID));
> but it does not work. With adding sliceID the program crash. Without it, I
> get only the first slice. How can i get a specific slice from the filter
> output?

Briefly reviewing the code, a few suggestions come to mind:

- Set all filenames to the ImageSeriesReader (instead of just one)
- Call ->UpdateLargestPossibleRegion() at the end of the pipeline
instead of just ->Update() when multiple pipeline calls are made to
ensure the LargestPossibleRegion is reset in the pipeline.
- Check out

  https://itk.org/Doxygen/html/Examples_2IO_2DicomSeriesReadImageWrite2_8cxx-example.html

for another example.


> You are right. About question four, isn't it possible to create an itk image
> from a collected voxels (this is the part I don't know) then convert it to
> vtk image like I did in the example?

Yes! More information and tips can be found here:

  https://blog.kitware.com/how-to-connect-itk-and-vtk-pipelines/
  https://itk.org/ITKExamples/src/Bridge/VtkGlue/ConvertAnitkImageTovtkImageData/Documentation.html

Hope this helps,
Matt