[ITK] ScaleVersor3DTransform

[Francois Budin]

Thanks Ziv for clarifying the transform description, and nice ipython
notebook! It would be awesome if you could update the documentation that is
confusing in ITK. Anybody is more than welcome to submit patches to improve
both the code and the documentation.
Information about how to participate is available here [1].

Francois

[1] https://itk.org/Wiki/ITK/Git/Develop

On Tue, Nov 1, 2016 at 3:56 PM, Yaniv, Ziv Rafael (NIH/NLM/LHC) [C] <
zivrafael.yaniv at nih.gov> wrote:

> Hi Tobias,
>
> Unfortunately the name of this transformation type is misleading, it is
> not what you expect, it adds a diagonal scale-1 matrix to the rotation
> matrix. I remember being surprised by this too but, in this rare case ;),
> the documentation says what it does:
>
>
> https://itk.org/Doxygen/html/classitk_1_1ScaleVersor3DTransform.html
>
>       regards
>           Ziv
>
> p.s. A description of most ITK transformation types is available in our
> SimpleITK notebooks repository
> (https://github.com/InsightSoftwareConsortium/
> SimpleITK-Notebooks/blob/mast
> er/Python/22_Transforms.ipynb). It illustrates the behavior of ITK
> transformations, some of which may be unexpected.
>
>
> On 11/1/16, 5:48 AM, "Wood, Tobias" <tobias.wood at kcl.ac.uk> wrote:
>
> >Hello,
> >
> >I tried to create a ScaleVersor3DTransform that applies an isotropic 0.1
> >scaling and a 180 degree rotation about Z. I am hence a bit confused
> >about how I get the following output when I print the Transform:
> >
> >ScaleVersor3DTransform (0x7f8a726789b0)
> >  RTTI typeinfo:   itk::ScaleVersor3DTransform<double>
> >  Reference Count: 1
> >  Modified Time: 209
> >  Debug: Off
> >  Object Name:
> >  Observers:
> >    none
> >  Matrix:
> >    -1.9 0 0
> >    0 -1.9 0
> >    0 0 0.1
> >  Offset: [0, 0, 0]
> >  Center: [0, 0, 0]
> >  Translation: [0, 0, 0]
> >  Inverse:
> >    -0.526316 0 0
> >    0 -0.526316 0
> >    0 0 10
> >  Singular: 0
> >  Versor: [ 0, 0, 1, 0 ]
> >  Scales:       [0.1, 0.1, 0.1]
> >
> >Not that the Scales and Versor parameters appear correct. However the
> >Matrix (and Inverse) look very badly wrong. I think the Matrix should be:
> >-0.1 0 0
> >0 -0.1 0
> >0 0 -0.1
> >
> >What have I misunderstood?
> >
> >Thanks,
> >Toby
> >
> >_______________________________________________
> >Community mailing list
> >Community at itk.org
> >http://public.kitware.com/mailman/listinfo/community
>
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