StructuredPointsToUnstructuredGrid

#include <vtkSmartPointer.h>
#include <vtkStructuredPoints.h>
#include <vtkXMLUnstructuredGridWriter.h>
#include <vtkUnstructuredGrid.h>

int main(int, char *[])
{
  // Create a structuredpoints
  vtkSmartPointer<vtkStructuredPoints> structuredPoints =
    vtkSmartPointer<vtkStructuredPoints>::New();

  // Specify the size of the image data
  structuredPoints->SetDimensions(2,3,1);
  structuredPoints->AllocateScalars(VTK_DOUBLE,1);

  int* dims = structuredPoints->GetDimensions();

  std::cout << "Dims: " << " x: " << dims[0] << " y: " << dims[1] << " z: " << dims[2] << std::endl;

  std::cout << "Number of points: " << structuredPoints->GetNumberOfPoints() << std::endl;
  std::cout << "Number of cells: " << structuredPoints->GetNumberOfCells() << std::endl;

  //fill every entry of the image data with "2.0"
  for (int z = 0; z < dims[2]; z++)
  {
    for (int y = 0; y < dims[1]; y++)
    {
      for (int x = 0; x < dims[0]; x++)
      {
        double* pixel = static_cast<double*>(structuredPoints->GetScalarPointer(x,y,z));
        pixel[0] = 2.0;
      }
    }
  }


  // Copy the points from the StructuredPoints to the UnstructuredGrid
  vtkSmartPointer<vtkPoints> points =
    vtkSmartPointer<vtkPoints>::New();

  //retrieve the entries from the grid and print them to the screen
  for(vtkIdType i = 0; i < structuredPoints->GetNumberOfPoints(); i++)
  {
    double p[3];
    structuredPoints->GetPoint(i, p);

    points->InsertNextPoint(p);
  }

  vtkSmartPointer<vtkUnstructuredGrid> ug =
    vtkSmartPointer<vtkUnstructuredGrid>::New();
  ug->SetPoints(points);

  vtkSmartPointer<vtkXMLUnstructuredGridWriter> writer =
    vtkSmartPointer<vtkXMLUnstructuredGridWriter>::New();
  writer->SetFileName("output.vtu");
  writer->SetInputData(ug);
  writer->Write();

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(StructuredPointsToUnstructuredGrid)

find_package(VTK COMPONENTS 
  vtkvtkCommonCore
  vtkvtkCommonDataModel
  vtkvtkIOXML QUIET)
if (NOT VTK_FOUND)
  message("Skipping StructuredPointsToUnstructuredGrid: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(StructuredPointsToUnstructuredGrid MACOSX_BUNDLE StructuredPointsToUnstructuredGrid.cxx )
  target_link_libraries(StructuredPointsToUnstructuredGrid PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(StructuredPointsToUnstructuredGrid MACOSX_BUNDLE StructuredPointsToUnstructuredGrid.cxx )
  target_link_libraries(StructuredPointsToUnstructuredGrid PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS StructuredPointsToUnstructuredGrid
    MODULES ${VTK_LIBRARIES}
    )
endif ()

cd StructuredPointsToUnstructuredGrid/build

cmake ..

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

make

./StructuredPointsToUnstructuredGrid