[Insight-users] modify transformation parameters by usingitkBSplineDeformableTransform

Tue May 11 04:36:48 EDT 2010

Thank you for all your comments. I have finished writing this piece of code,
most of them are from this. http://elastix.isi.uu.nl/doxygen/a00228.html

On 11 May 2010 10:26, Magnotta, Vincent A <vincent-magnotta at uiowa.edu>wrote:

>  Xi,
>
> I would think that this would be easier to implement using a
> ThinPlateSpline Transform.
>
> Vince
>
>
> ----------------------
> Associate Professor
> Department of Radiology
> 0453-D JCP
> 200 Hawkins Drive
> Iowa City, IA 52242
> E-mail: vincent-magnotta at uiowa.edu
> Phone: 319-356-8255 Fax: 319-353-6275
> Website: http://www.radiology.uiowa.edu
>
>
>
>
> -----Original Message-----
> From: insight-users-bounces at itk.org on behalf of Xi Liang
> Sent: Sun 5/9/2010 7:50 PM
> To: Luis Ibanez
> Cc: insight-users at itk.org
> Subject: Re: [Insight-users] modify transformation parameters by
> usingitkBSplineDeformableTransform
>
> Hi Luis,
>
> Thank you for the response. I think I did not make my question clear, and
> the following is the purpose to write the code.
>
> My goal is not to create a Transform filter to be used in a registration. I
> want to create a simulated motion (include nonrigid and rigid
> deformations).
> I have a random nonrigid bspline deformation transformation parameters (can
> be easily get the corresponding deformation field), and a segment mask
> image. These two are my input. I want the output to be a nonrigid
> deformation field. This generated deformation field will be used on a image
> that has nonrigid and rigid structures, where the rigid area is the same as
> the input segment mask. Therefore I need to either modify the
> transformation
> parameters, or the corresponding deformation field to achieve a partial
> rigid deformations.
>
> I am currently modifying a filter based on
> http://elastix.isi.uu.nl/doxygen/a00228.html. I am reading the ITK
> software
> guide and try to understand how it works. The author Marius Staring told me
> It can be easily modified to fill my need -- assigning a subset of a
> deformation field with its mean value.
>
> Luis, you suggest that there are better ways to implement a Transform that
> behaved as a Translation (or rigid) transformation in some regions and as
> Deformable in others. What is that? Is that similar to the above method? to
> modify the deformation field. Or you suggest a different scheme?
>
>
> 1) If you want to implement a Transform that behaves as
>    a Translation (or Rigid) transform in some regions and
>    as Deformable in others, there are better ways of
>    implementing such class, than fiddling with the parameters
>    of the BSplineDeformable transfrom.
>
> On 10 May 2010 07:50, Luis Ibanez <luis.ibanez at kitware.com> wrote:
>
> > Hi Xi,
> >
> >
> > 1) If you want to implement a Transform that behaves as
> >    a Translation (or Rigid) transform in some regions and
> >    as Deformable in others, there are better ways of
> >    implementing such class, than fiddling with the parameters
> >    of the BSplineDeformable transfrom.
> >
> > 2) But, just to answer your question. The parameter array
> >    of the BSpline transform has the components of the
> >    deformation vectors at every node of the BSpline grid.
> >
> >    Given a BSpline grid with N nodes in 3D, you will have
> >
> >                          3 x N        parameters
> >
> >    and they are arranged as:
> >
> >      X1,X2,X3....... Xn,  Y1,Y2,Y3.....YN,...Z1, Z2, Z3,... ZN
> >
> >
> > 3) You can change those parameters manually.
> >    Simply have to figure out which BSpline nodes
> >    are on top of the regions for which you want to
> >    allow only Translations, and change those
> >    accordingly.
> >
> >
> >
> >
> >   Regards,
> >
> >
> >       Luis
> >
> >
> >
> > ---------------------------------------------
> > On Wed, May 5, 2010 at 6:58 AM, Xi Liang <liangxi1986317 at hotmail.com>
> > wrote:
> > > Dear all,
> > > I want to change the some control point parameters got by running
> > > registration by using itkBSplineDeformableTransform.h. The reason is to
> > > manually modify a set of control points such that only translation is
> > > applied on the corresponding regions. The question I would like to ask
> is
> > > whether this should be done manually, or we have a filter to change
> those
> > > parameters?
> > > If I have to do this manually, I will have to understand of the format
> of
> > > parameters. I understand the number of parameters get
> > > from itkBSplineDeformableTransform is ImageDimension *
> > > (numberOfGridNodesInOneDimension + BsplineOrder). Which value is for
> > > lower/upper borders, and which are for nodes? I think I will only need
> to
> > > modify the node values to enforce the translation transformations.
> > > This method is introduced by Tanner in Volume and Shape Preservation of
> > > Enhancing Lesions when applying nonrigid registration to a time series
> of
> > > contrast enhancing MR breast Images. It couples the control points of a
> > > bspline deformation to enforce rigidity on certain structures.
> > > Kind regards,
> > > Xi
> > >
> > >
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