[ITK-users] MultiThreading, ImageRegionIterator crash

[Nicolas Courtial]

Hello everyone,

I'm quite new in ITK world, and I'm currently doing few experiences in 
order to learn its logic.

After few easy exercices, I'm now at a step I want to multithread a method.
As I did in the past, I've been reading the ITK classes to get 
"inspiration", and e- mails from here in case of troubles.

I'm facing an issue at the moment, and I can't figure why, and how to 
solve it.

My filter works with

  * One 3D InputImage (of any pixel type)
  * Two "tool" 3D images, respectively of float and unsigned char pixel
    types

 From what I read, I've understood there are two main ways of 
multithreading:

  * The old fashioned one using
    BeforeThreadedGenerateData/ThreadedGenerateData/AfterThreadedGenerateData
  * the one using itk::DomainThreader member.

As I'm a bit old school, I used the first option.

My problem remains here: (I changed my variables' name to make it clearer)

ThreadedComputation(const OutputImageRegionType &outputRegionForThread, 
ThreadIdType threadId) {
         itk::ProgressReporter progress(this, threadId, 
outputRegionForThread.GetNumberOfPixels());
         typename TOutputImage::Pointer image = this->GetOutput(0);

         itk::ImageRegionIterator< TOutputImage > imgIt(image, 
outputRegionForThread);
         itk::ImageRegionIterator< FloatImageType> floatIt 
(m_MyFloatImage, outputRegionForThread);
     ....

When creating the floatIt iterator, I have a crash. Using a try catch 
block, the issue is due to out of bound region.
Everything is correct, but the index, for which it's completly crazy 
([156245468,0,156245468] or something approching).

I've tried different options to solve this, but rather than doing 
witchcraft and at some point getting something working, I'd prefer to 
improve my understanding thanks to your expertise.

Thanks all,

Nicolas Courtial




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