[vtkusers] vtkPoints from a triangular vtkPolyData

[imho]

Hi all,
I'd like to use the vtkThinPlateSplineTransform, who needs vtkPoints 
structures.
I've tried poly->getPoints()  but it was empty, so here's what I've done:
models are vtkPolyData
TPSTarget and Origine  vtkPoints

        n1 = modelTarget->GetNumberOfPoints();
        n2 = modelToMove->GetNumberOfPoints();
        if (n1 < n2)
            n=n1;
        else
            n=n2;

        for (i=0; i<n; i++)
        {
            modelTarget->GetPoint(i,point);
            TPSTarget->InsertNextPoint(point);
        }
       
       
        for (i=0; i<n; i++)
        {
            modelToMove->GetPoint(i,point);
            TPSOrigine->InsertNextPoint(point);
        }
       
       
        TPSTr->SetSourceLandmarks(TPSOrigine);
        TPSTr->SetTargetLandmarks(TPSTarget);

and then :
    tf3 = vtkTransformPolyDataFilter::New();

    tf3->SetTransform(TPSTr);
    tf3->SetInput(poly);
    tf3->Update();
   
    return (tf3->GetOutput());

but it does nothing, my poly is the same on input and output., for the 
same reason before I guess.
What can I try to have points from my polyData?

Thanks