[Insight-users] Specifying landmarks in the ThinPlateSplineWarp.cxx example?

[Luis Ibanez]

Hi Motes,


          "Glimpsing at the source leaves no doubt"


If you look at lines 120-130 of the ThinPlateSplineWarp.cxx file:

  while (!infile.eof())
    {
    infile >>  p1[0] >> p1[1] >> p1[2] >> p2[0] >> p2[1] >> p2[2];

    sourceLandMarkContainer->InsertElement( id, p1 );
    targetLandMarkContainer->InsertElement( id++, p2 );
    }

You will see that the first three values of the file are assigned
to the X,Y,Z coordinates of the first source landmark, while the
second group of three values is assigned to the X,Y,Z coordinates
of the first landmark in the group of target landmarks.


Note that this is different from how we manage BSplineDeformableTransforms.

In this ThinPlateSpline example there are no deformation vectors.  We use
a group of landmarks in the Fixed image, that map, one-to-one, to landmarks
in the moving image.

The triplet ( 180  217  0 )  that you pointed out to in your email,
correspond
indeed to the coordinates of a point in the space of the fixed image.

It is the point with coordinates:   X = 180.0, Y = 217.0,  Z = 0.0


     Regards,


            Luis


--------------------------------------------------------------------------------------------
On Sun, Aug 16, 2009 at 2:10 AM, motes motes <mort.motes at gmail.com> wrote:

> In the ThinPlateSplineWarp.cxx a set of landmarks are read from the file
> LandmarkWarping3Landmarks1.txt which contains this:
>
>   0   0   0        0   0      0
> 180   0   0      180   0      0
> 180 217   0      180 217      0
>   0 217   0        0 217      0
>   0   0 180        0   0    180
> 180   0 180      180   0    180
> 180 217 180      180 217    180
>   0 217 180        0 217    180
>  90 108  90       90 130     90
>
>
>
> As I understand these are 18 landmark points which is actually just
> deformation vectors. So the 3 first values in the third row:
>
> 180  217  0
>
> corresponds to a vector at some location pointing 180 unit in the
> x-direction and 217 units in the y-direction.
>
> But where in the image is this vector located?
>
> Or are the above landmarks just 'regular' points that are interpolated by
> the ThinPlateSpline and not deformation vectors?
>
>
>
> _____________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the ITK FAQ at:
> http://www.itk.org/Wiki/ITK_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.itk.org/mailman/listinfo/insight-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.itk.org/pipermail/insight-users/attachments/20090816/ee85b59e/attachment.htm>