[vtkusers] Locating a 3D position in 3D scheme from a XYZ coordinates

[Wagner Sales]

Hi all,

May be the title are not the best, but i'll explain better the problem:
a) I have a 2D viewer that's shows to me slices from a serie. This 2D viewer
aren't VTK based.
b) I use this 2D viewer to mark seed points for segmentation. The
segmentation works fine for various datasets, then I think the positions
that's I have for marked points are ok.
c) I show the results of segmentation on a 3D view ( ITKImage -> VTKImage ->
vtkContourFilter -> vtkPolyData -> vtkPolyDataMapper -> vtkActor, I think ).
Thats works fine too.
d) I need to mark a point on the 2D viewer and shows this point on 3D view.

After some search, I do:

      paraCoords = new double[3];
      xyzCoords  = new double[3];
      vtkcellweights = new double[4];
      q = new int[3];
        if(!m_CurrentImageData)
        {
                xyzCoords[0] = 0.0;
                xyzCoords[1] = 0.0;
                xyzCoords[2] = 0.0;
                return xyzCoords;
        }
        q[0] = m_XPosition;
        q[1] = m_YPosition;
        q[2] = m_ZPosition;
        cellNum = m_CurrentImageData->ComputeCellId(q);
        subID = m_CurrentImageData->GetCell( cellNum
)->GetParametricCenter(paraCoords);
        int &subIDadd = subID;
        m_CurrentImageData->GetCell(cellNum)->EvaluateLocation(subIDadd,
paraCoords,
        xyzCoords, vtkcellweights);
        return xyzCoords;


Well, the position, when returned, are ok. But some times this crashes ( and
debugger output are useless ). Running under valgrind (I'm on a linux
machine), this shows a useful backtrace, that's passes to this method and go
to vtkVoxel::EvaluateLocation method, where the crash occurs. I tried then
to use vtkCoordinate to convert coordinates, setting all the system
coordinates and getting all the converted values, and no ones are equals the
values I have from my current approach.
Since I'm running on this problem a couple of days, someone can helps? (
another approach, whats wrong, etc ). My VTK version are 5.2 stable.

Regards,

Wagner Sales
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