[Insight-users] DICOMParser, GDCM?

[Miller, James V (Research)]

The long term answer is that GDCM will be the preferred DICOM import/export utility.
 
In the short term, it looks like the code in DICOMAppHelper has the wrong sign on the y component of the normal.  Probably a cut and paste error. I expect this has a nasty effect of forcing the vector to be 90 degrees off where is supposed to be. Since the normal is only used for computing a sorted filelist, I am not sure what impact it would have had. It might have affected oblique volumes.
 
When my builds finish, I'll run a few tests and check in a fix...
 
Jim
 

-----Original Message-----
From: insight-users-bounces at itk.org [mailto:insight-users-bounces at itk.org]On Behalf Of Roxana Racz
Sent: Monday, March 14, 2005 2:04 PM
To: insight-users at itk.org
Subject: [Insight-users] DICOMParser, GDCM? 


Hi all!
 
I have to do an  aplication , that  must be able to register volumes having different orientations. 
 
For reading the series of DICOM images I tried both libraries : DICOMParser, gdcm 

Between the 2 libraries I observed the following difference regarding the computation of normal used to sort the files by Image Position Patient 
 
- in DICOMParser: file DICOMAppHelper.cxx ,functionGetImagePositionPatientFilenamePairs,  line 2244 :
          normal[1] = ((*sn_iter).second.ImageOrientationPatient[0]                    
*(*sn_iter).second.ImageOrientationPatient[5])
 -    
((*sn_iter).second.ImageOrientationPatient[2]*    
(*sn_iter).second.ImageOrientationPatient[3]);
 
- in gdcm :  file gdcmHeaderHelper.cxx, function ImagePositionPatientOrdering(), line 184 :
          normal[1] = cosines[2]*cosines[3] - cosines[0]*cosines[5];
 
This difference influence the coordinate system of the resulting image volume.
How is correct?
 
I want to use itkOrientImageFilter to bring all the volume to a single coordinate system.This filter has to know the coordinate system of the input image. 

The question I have is : How can I found out the coordinate system of the image I get from the reader in both cases : when I use DICOMParser and when I use gdcm  ? (in both cases I want  the files to be read  ascending , by Image Position Patient) 
 
I use itk 2.0
 
Thank you in advance! 
Roxana

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