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

[Bill Lorensen]

I believe that the DICOM origin is in LPS. itk volumes are stored in the 
acquisition order. Therefore, the DICOM origin must be transformed.

Clear to me (I think)...

Bill

At 07:28 PM 1/17/2006, Luis Ibanez wrote:

>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
>>
>
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