[vtkusers] vtkLandmarkTransform incorrect results?

[David Gobbi]

Hi David,

The vtkLandmarkTransform requires that the two sets of vtkPoints are
homologous with each other, i.e. they must each represent the same set
of landmarks listed in the same order.  Using it to register polydata
by taking the points from each data set is a bad idea, since the
points are probably not going to be homologous.  You should use
iterative closest point instead.

    David


On Tue, Nov 10, 2009 at 7:47 AM, David Doria <daviddoria+vtk at gmail.com> wrote:
> I have written a filter to compute and apply a LandmarkTransform to a
> polydata. An explanation along with a paraview plugin of the filter
> are here: http://www.paraview.org/Wiki/ParaView#Registration
> (http://www.paraview.org/Wiki/images/e/e0/LandmarkTransformPlugin.zip).
>
> With three landmarks
> (http://www.rpi.edu/~doriad/VTK_List/LandmarkTransformFilter/Working),
> the transform works correctly. However, with many landmarks
> (http://www.rpi.edu/~doriad/VTK_List/LandmarkTransformFilter/NotWorking),
> the transform doesn't produce the correct result - the transformed
> dataset does not get scaled nearly enough to match the target dataset.
>
> Can anyone comment on this? I though as the number of landmarks
> increased the transformation should become a better estimate?
>
> Thanks,
>
> David
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