[Insight-developers] [Insight-registration] vector transformation / reorientation

[Luis Ibanez]

On Sat, Nov 20, 2010 at 7:14 PM, Matthew McCormick (thewtex) <
matt at mmmccormick.com> wrote:

> On Sat, Nov 20, 2010 at 6:07 PM, Luis Ibanez <luis.ibanez at kitware.com>
> wrote:
> >
> >
> > On Sat, Nov 20, 2010 at 7:00 PM, Matthew McCormick (thewtex)
> > <matt at mmmccormick.com> wrote:
> >>
> >> >
> >> > (b) Estimating the Rotational and Stress component of the
> >> >       deformation field at that pixel location and use it to correct
> >> >       the Vector (or covariant vector) accordingly.  This is
> >> >       essentially based on the Jacobian matrix of the deformation
> >> >       field, estimated at the location of the pixel.
> >> >
> >>
> >> I have a StrainImageFilter that calculates the strain tensor from a
> >> deformation field if it would be of any help.  I assume what is meant
> >> by the 'Rotational and Stress component' are the same as the angles to
> >> the principle strains and the principle strains.  I intend on
> >> submitting this filter to the Insight Journal in the next week or two
> >> after I get another paper out and the following patch gets merged:
> >>
> >>
> >>
> http://review.source.kitware.com/#q,status:open+project:ITK+branch:master+topic:BUG0010725_VTKTensors3,n,z
> >>
> >> Matt
> >
> >
> > Excellent !
> >
> > Yes,
> > that what I meant by the stress component.
> >
> > Do you see a way of deriving as well
> > the rotational component of the Jacobian  ?
> >
>
> I was thinking just using
>
> http://www.itk.org/Doxygen320/html/classitk_1_1SymmetricEigenAnalysis.html#_details
>
> And the eigenvectors determine the rotation, while the eigenvalues
> (principle strains) determine the compression/expansion of the
> components?  Correct?
>
> Matt
>


Yes,
That sound very reasonable to me.


     Luis
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