[Insight-users] RE: [Insight-developers] itkOrientedImage type definition

[Lorensen, William E (Research)]

I believe that the direction cosines in ITK are always in LPS. I just copy in the dicom direction cosines.

Bill

-----Original Message-----
From: insight-developers-bounces+lorensen=crd.ge.com at itk.org
[mailto:insight-developers-bounces+lorensen=crd.ge.com at itk.org]On Behalf
Of Simon Warfield
Sent: Thursday, August 18, 2005 3:01 PM
To: insight-users at itk.org; insight-developers at itk.org
Subject: [Insight-developers] itkOrientedImage type definition



I am looking at the documentation that describes directions here:
http://www.itk.org/Doxygen/html/classitk_1_1Image.html#w14

This indicates that there is the possibility to represent a matrix of 
direction cosines.
Direction cosines represent the angle between two sets of basis vectors.
http://mathworld.wolfram.com/DirectionCosine.html

In order to understand what the orientation of an itkOrientedImage is, 
there must be some way to specify or to record what those basis vectors are.
For example, the definition of DICOM direction cosines warrants that 
what is being provided is the angle between the patients anatomy in what 
is referred to as the Left-Posterior-Superior orientation and the image 
columns and rows.

  With respect to what are the ITK direction cosines computed ?  If it 
is not specified then the orientation of an image containing such 
direction cosines is still unknown, which would defeat the purpose of 
providing an orientation.

--
Simon

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