Processing ExodusII data

Support
1

Hello,
I am new to VTK. Here is what I need to do:

  1. Read exodusII file. The exodus file contains spatio-temporal data for multiple scalar variables. Choose a particular scalar variable.
  2. Apply a threshold filter to the chosen scalar variable and extract the mesh nodes satisfying the threshold condition (along with node connectivities)
  3. Perform the above steps for another exodus file.
  4. Perform a boolean intersection of the two thresholded sets of nodes.
  5. Write the resulting nodes to a vtu/exodus file.

I went through the examples and the doxygen pages, but I can’t find an example doing what I want. I am also getting confused by the different data classes. Could someone please give me some hints for this purpose?

Best regards,
Nikhil

2

I found some examples which wanted to do similar things and I put together the following code:

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkLookupTable.h>
#include <vtkNamedColors.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkPolyhedron.h>
#include <vtkProperty.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.h>
#include <vtkExodusIIReader.h>
#include <vtkExodusIIWriter.h>
#include <vtkThresholdPoints.h>
#include <vtkMultiBlockDataSet.h>
#include <vtkDataSet.h>

int main (int, char *[])
{
int time_step_begin, time_step_end;

vtkSmartPointer reader = vtkExodusIIReader::New();
reader->SetFileName("/home/2014-0004_focal_therapy/PhDs/AdapTT/Nikhil/DwarfElephant/Dodecahedron/AdvectionDiffusionModel_3D_meshConv_0_out.e");
reader->UpdateInformation();
reader->GetTimeStepRange(time_step_begin, time_step_end);
reader->SetTimeStep(time_step_end);

for (int i = 0 ; i < reader->GetNumberOfObjectArrays(reader->NODAL); i++)
{
std::string nname;
nname = reader->GetObjectArrayName(vtkExodusIIReader::NODAL,i);
if (nname == “ThermalDamage”)
reader->SetObjectArrayStatus(vtkExodusIIReader::NODAL,i,1);
}

vtkSmartPointer threshold = vtkThresholdPoints::New();
threshold->SetInputConnection(reader->GetOutputPort());
threshold->ThresholdByLower(1.0);
threshold->SetInputArrayToProcess(0,0,0,vtkDataObject::FIELD_ASSOCIATION_POINTS,“ThermalDamage”);
threshold->Update();

vtkSmartPointer writer = vtkExodusIIWriter::New();
writer->SetFileName(“FinalLesion.e”);
writer->SetInputData(threshold->GetOutput());
writer->WriteAllTimeStepsOn();
writer->Write();

return EXIT_SUCCESS;
}

When I run the code I get the following error message:
vtkExodusIIWriter (0x9964c0): No input provided!

How should I give input to the exodusII writer?

Best
Nikhil