 Direction Cosines are required to be normed (was Re: Where is leftand right position in CT axial image? And about DICOMDIR)
On Aug 22, 10:11*pm, Yves Martel wrote:
> Any float values are permitted. *Though since these should be normed
> vectors, the sqrt( x*x + y*y + z*z ) should be == 1. *But even thatI
> don't believe it is required by the specs (somebody correct me if I'm
> wrong...)
I reported that earlier. AFAIK Image Orientation (Patient) (0020,0037)
is simply VR=DS with VM=6 that's all what the standard says.
But clearly if one reads C.7.6.2.1.1 Image Position And Image
Orientation, the values have to be cos/sin values (no normalization
appear in the matrix). The fact that x*x + y*y + z*z == 1 is not
enough, you also need that dot product is 0 (x[0]*y[0] + x[1]*y[1] +
x[2]*y[2] == 0)
From the top of my head I think that :
* Rescale Slope=0 is also a valid value.
* Pixel Spacing (0,0) is also valid
...
Again those are good example for a DICOM Conformance Tests
-Mathieu
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