[Insight-developers] [GDCM] ITK Origin and coordinate system

[Luis Ibanez]

Mmm,

Now we are in trouble,...
because experimentation is the ultimate source of knowledge.

and Bill's experiment shows that the origin is not what we
were assuming to be.


Can it be that scanners report the origin already in terms
of the direction cosines ?


That is,

    The position is given already as a translation along
    the directions of the axis....


Mathieu:

  Is there anything in the DICOM specifications that defines the
  relationship between the origin and the direction cosines ?


Maybe the current GDCM is doing the right thing, and all
other implementations are missing to interpret the origin
in terms of displacements along the axis of the scan...



    Luis



--------------------
Bill Lorensen wrote:
> In an experiment I did a few months back, I had 6 MR scans done of the 
> same object in each of the 6 orthogonal directions. I read them in using 
> the current GDCMImageIO  (which transforms the origin using the 
> direction cosines). All of the volumes roughly lined up without any 
> additional transformations.
> 
> If I did not apply the direction cosines, the datasets were all shifted.
> 
> Go figure,
> 
> Bill
> 
> 
>