vtkDataSet* aDataSet = myMergeFilter->GetOutput();
vtkIdType anID = myVisualObj->GetNodeVTKId(theObjID);
double* aCoord = (anID >=0 && anID < aDataSet->GetNumberOfPoints()) ? aDataSet->GetPoint(anID) : NULL;
vtkDataSet* aDataSet = myMergeFilter->GetOutput();
vtkIdType anID = myVisualObj->GetNodeVTKId(theObjID);
double* aCoord = (anID >=0 && anID < aDataSet->GetNumberOfPoints()) ? aDataSet->GetPoint(anID) : NULL;