[vtkusers] voxel's volume

[Mathieu Malaterre]

> I do agree with Mathieu.
> You cannot get the voxel Z Size reading just an image.
> You need 2 images, get the Date Element 0x0020,0x0032 --> Image Position 
> (Patient), and compute the Z spacing.
> Mathieu :
> Don't you think we (I) should add GDCM a method to do that (you pass the 
> 2 "Image Position (Patient)", and it returns zspacing.
> My question : I add it on *which* class (noy on File, not on FileHelper, 
> not on Document ...?)

I'll answer that on dcmlib

> --> Probabely a misstyping : Image Position (Patient) is the right one, 
> isn't it?
> 
>> Image Orientation (Patient) 

Sorry I was not clear at all... So in summary to compute the zspacing 
you need:
* Image Position (Patient)
* Image Orientation (Patient)  (to get the normal)

The original email with plenty of details can be found at:
http://www.itk.org/pipermail/insight-users/2003-September/004762.html

And an implementation can be found in 
gdcm::SerieHelper::ImagePositionPatientOrdering
(gdcmSerieHelper.cxx)

HTH
Mathieu