[Insight-users] Affine transform - decomposition ?

[Stephen R. Aylward]

One option is to use the itkScaleSkewVersor3DTransform - its parameters 
are a decomposition of the affine transform.

If you figure out a good way to decompose an affine transform, this 
class could use it in the ComputeMatrixParameters member function.  I 
haven't done any research into such decomposition...

Stephen

Roxana Racz wrote:
> Hello everyone,
> 
> I am working on a registration application.
> I would like to display the **geometrically meaningful** components using 
> the 12 parameters of the affine transform as returned by the registration 
> routine. 
> 
> That is: from the 12 "raw" parameters returned by the registration algorithm 
> employed, I need to be able to monitor the following quantities: 
> 1.translation(3), 
> 2.rotation(3), 
> 3.scaling(3), 
> 4.skew(?) and 
> 5.reflection(3?)
> 
> --- Does anyone know of a method based on itk? (it seems that vtk offers 
> only the extraction of 1, 2, 3: GetPosition, GetOrientation, GetScale, all 
> defined in vtkTransform.cxx).
> 
> --- Could anyone recommend a good reading on the underlying maths for this 
> extractions? 
> Thanks in advance,
>  Roxana
> 
> 
> 
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-- 
===========================================================
Dr. Stephen R. Aylward
Associate Professor of Radiology
Adjunct Associate Professor of Computer Science and Surgery
http://caddlab.rad.unc.edu
aylward at unc.edu
(919) 966-9695