[vtkusers] Landmark transform works on polydata, but not vtkPoints

[David Doria]

I have these points:
    vtkSmartPointer<vtkPoints> SourcePoints =
vtkSmartPointer<vtkPoints>::New();
    vtkSmartPointer<vtkPoints> TargetPoints =
vtkSmartPointer<vtkPoints>::New();
 // ... fill points ...

If I use them to make a landmark transform:

    LandmarkTransform->SetSourceLandmarks(SourcePoints);
    LandmarkTransform->SetTargetLandmarks(TargetPoints);
    LandmarkTransform->SetModeToRigidBody();

and then transform a polydata with the landmark transform:

    vtkSmartPointer<vtkTransformPolyDataFilter> TransFilter =
vtkSmartPointer<vtkTransformPolyDataFilter>::New();
    TransFilter->SetInput(Model.CreatePolydata());
    TransFilter->SetTransform(LandmarkTransform);
    TransFilter->Update();
    vtkPolyData* polydata = TransFilter->GetOutput();

Everything works as expected. However, if I try to transform the points
directly:

    vtkSmartPointer<vtkPoints> TransformedModelPoints =
vtkSmartPointer<vtkPoints>::New();
    LandmarkTransform->TransformPoints(SourcePoints,
TransformedModelPoints);

everything turns into nan, ie
        double origpoint[3];
        SourcePoints->GetPoint(i, origpoint);
the result is [nan, nan, nan]

I'm sure I'm just using the TransformPoints() function wrong - does anyone
know how to do it properly?

Thanks,

David
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