[Insight-users] Get and Set itk Origin

[jef vdmb]

Indeed, the index is negative.  Thanks for the hint!
Looking at  itk::ImageFileWriter::Write()

  // BUG 8436: Wrong origin when writing a file with non-zero index
  // origin = input->GetOrigin();
  const typename TInputImage::IndexType& startIndex = largestRegion.GetIndex();
  typename TInputImage::PointType origin;  
  input->TransformIndexToPhysicalPoint(startIndex, origin);

A non-zero index explicitely needs to be converted to a new origin.  
So when using the origin (of an image with non-zero index), one should also pass the index... this is a bit dangerous no?

Thanks again,
Jef


> Subject: Re: [Insight-users] Get and Set itk Origin
> From: hobbsk at ohiou.edu
> To: jvdmb at hotmail.com
> CC: insight-users at itk.org
> Date: Tue, 15 Sep 2009 12:57:43 -0400
> 
> On Tue, 2009-09-15 at 09:32 +0000, jef vdmb wrote:
> 
> > The initial input had origin (0,0,0). The output however should have
> > an origin different from zero (with the parameters I used for the
> > MirrorPadImageFilter). When the output is interrogated for its origin
> > (->GetOrigin() ), it (wrongly) shows all zeros. When writing the image
> > afterwards, it was written with the correct origin ( offset field of
> > the .mhd image format). 
> 
> 
> I bet that if you get the index of the region of the output image, you
> will see that it has negative numbers.
> 
> Only when the image is written is the new origin calculated.

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