[vtkusers] creating a vtkSpline to transform within a pipeline

[Anant Vemuri]

thank you for the prompt reply. I will check that.


On Mon, Sep 17, 2012 at 12:57 PM, David Gobbi <david.gobbi at gmail.com> wrote:

> Hi Anant,
>
> The example program that you are trying to run was made for VTK 6.  If
> you have a copy of the VTK 5.10 source code, look for
> Hybrid/Testing/Cxx/TestBSplineWarp.cxx and use that instead.
>
> The vtkBSplineTransform doesn't manage missing points.  For that,
> someone would need to add an algorithm to VTK like the one described
> in this paper:
>
> Seungyong Lee, George Wolberg, and Sung Yong Shin,
> Scattered Data Interpolation with Multilevel B-Splines
> IEEE Transactions on Visualization and Computer Graphics,
> Vol. 3, pp. 228-244, 1997
>
>  - David
>
> On Mon, Sep 17, 2012 at 2:03 AM, Anant Vemuri <ajar108 at gmail.com> wrote:
> > Hi David,
> >
> > Thanks... that is exactly what I want to do. I was wondering, how does it
> > manage missing points.
> >
> > Another thing, I tried to compile the test program on vtk documentation
> > website
> >
> >
> http://vtk.org/gitweb?p=VTK.git;a=blob_plain;f=Filters/Hybrid/Testing/Cxx/TestBSplineWarp.cxx
> >
> > and I get an error as,
> >
> > error: ‘class vtkBSplineTransform’ has no member named
> ‘SetCoefficientData’.
> >
> > Thanks,
> > Anant.
> >
> >
> > On Fri, Sep 14, 2012 at 2:37 PM, David Gobbi <david.gobbi at gmail.com>
> wrote:
> >>
> >> Hi Anant,
> >>
> >> If you recompute the spline coefficients within the transform's
> >> Update() method, then it should provide the sort of pipeline behavior
> >> that you are looking for.  The following paper describes the VTK
> >> transform update mechanism:
> >> http://www.ncbi.nlm.nih.gov/pubmed/12631510
> >>
> >> I added a vtkBSplineTransform to VTK 5.10.  It might satisfy your
> >> needs, and if not, you might be able to re-use parts of it:
> >> http://hdl.handle.net/10380/3252
> >>
> >>  - David
> >>
> >> On Fri, Sep 14, 2012 at 4:02 AM, Anant Vemuri <ajar108 at gmail.com>
> wrote:
> >> > I am currently creating a spline using vtkSplineFilter. The points in
> >> > the
> >> > spline are changing as new positions for points are generated.
> However,
> >> > now
> >> > I want to put the position information into a vtkTransform and connect
> >> > the
> >> > Spline being created within a pipeline so that, it gets updated when
> the
> >> > the
> >> > transform changes.
> >> >
> >> > currently I am doing this whenever I get new positions. Is it possible
> >> > to
> >> > put this in a pipeline so that the points are updated using a
> >> > vtktransform
> >> > when the transform changes. In vtkTransform there is a function called
> >> > "MultiplyPoint" and "TransformPoint", however both are not indicated
> to
> >> > be
> >> > pipelined.
> >> >
> >> > I am curious if anyone has tried to do this, or if anyone has
> >> > suggestions on
> >> > this issue.
> >> >
> >> > myspline is a class containing vtkPoints, vtkPolyLine, vtkPolyData
> etc.
> >> >
> >> >
> >> >     //   In the constructor for my spline class
> >> >     _points       = vtkSmartPointer< vtkPoints >::New();
> >> >     _polyLine     = vtkSmartPointer< vtkPolyLine >::New();
> >> >     _cells        = vtkSmartPointer< vtkCellArray >::New();
> >> >     _polyData     = vtkSmartPointer< vtkPolyData >::New();
> >> >     _splineFilter = vtkSmartPointer< vtkSplineFilter >::New();
> >> >     _tubeFilter   = vtkSmartPointer< vtkTubeFilter >::New();
> >> >
> >> >     //   PIPELINE
> >> >     _cells->InsertNextCell(_polyLine);
> >> >     _polyData->SetPoints(_points);
> >> >     _polyData->SetLines(_cells);
> >> >     _splinefilter->SetInput( _polyData );
> >> >     _splinefilter->SetMaximumNumberOfSubdivisions( 48 );
> >> >     _tubeFilter->SetInputConnection( _splineFilter->GetOutputPort());
> >> >     _tubeFilter->SetNumberOfSides( 12 );
> >> >     _tubeFilter->SetRadius( 5.0 );
> >> >     _tubeFilter->SetCapping(true);
> >> >     _mapper->SetInputConnection( _tubeFilter->GetOutputPort() );
> >> >     _actor->SetMapper(_mapper);
> >> >     _actor->GetProperty()->SetLineWidth(4);
> >> >
> >> >     //----------------------------------------------------------------
> >> >     // Updating for new vtkpoints
> >> >
> >> >     // I want to put this part into the pipeline if possible so that
> >> >     // i can apply a vtkTransform to lets say the _points and the
> spline
> >> >     // gets updated automatically. The updated _points that I get are
> >> >
> >> >     // absolute positions so I cannot appl
> >> >     splineObj->getPoints()->Reset();
> >> >     splineObj->getPolyLine()->GetPointIds()->Reset();
> >> >     vtkIdType k = 0;
> >> >
> >> >     // __scanorder contains the order in which the points need to be
> put
> >> > into a spline
> >> >     // __positions contains the updated point locations
> >> >     for (int j = 0; j < __scanOrder.size(); j++)
> >> >     {
> >> >          unsigned int __idx = __scanOrder[i][j]-1;
> >> >          double &__coord = __positions[__idx]->getCoordinate();
> >> >
> >> >
> >> >
> >> >
> splineObj->getPoints()->InsertNextPoint(__coord[0],__coord[1],__coord[2]);
> >> >          splineObj->getPolyLine()->GetPointIds()->InsertNextId( k );
> >> >          k++;
> >> >     }
> >> >     splineObj->getCellArray()->Reset();
> >> >
> splineObj->getCellArray()->InsertNextCell(splineObj->getPolyLine());
> >> >     splineObj->getPolyData()->Modified();
> >> >
> >> >
> >> > Thank you,
> >> >
> >> > Anant.
> >
> >
>
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