VTK/Examples/Cxx/PolyData/PolyDataToUnstructuredGrid

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There is not a filter whose sole purpose is converting a vtkPolyData to a vtkUnstructuredGrid. However, the append filter can accept any type of input, and produces a vtkUnstructuredGrid, so we can use it for this purpose.

PolyDataToUnstructuredGrid.cxx

#include <vtkAppendFilter.h>
#include <vtkPolyData.h>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkUnstructuredGrid.h>
#include <vtkVersion.h>
#include <vtkXMLUnstructuredGridWriter.h>
 
int main(int, char *[])
{
  // Create a sphere
  vtkSmartPointer<vtkSphereSource> sphereSource =
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(5.0);
  sphereSource->Update();
 
  // Combine the two data sets
  vtkSmartPointer<vtkAppendFilter> appendFilter =
    vtkSmartPointer<vtkAppendFilter>::New();
#if VTK_MAJOR_VERSION <= 5
  appendFilter->AddInput(sphereSource->GetOutput());
#else
  appendFilter->AddInputData(sphereSource->GetOutput());
#endif
  appendFilter->Update();
 
  vtkSmartPointer<vtkUnstructuredGrid> unstructuredGrid =
     vtkSmartPointer<vtkUnstructuredGrid>::New();
  unstructuredGrid->ShallowCopy(appendFilter->GetOutput());
 
  // Write the unstructured grid
  vtkSmartPointer<vtkXMLUnstructuredGridWriter> writer =
    vtkSmartPointer<vtkXMLUnstructuredGridWriter>::New();
  writer->SetFileName("UnstructuredGrid.vtu");
  #if VTK_MAJOR_VERSION <= 5
    writer->SetInput(unstructuredGrid);
  #else
    writer->SetInputData(unstructuredGrid);
  #endif
  writer->Write();
 
  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)
 
PROJECT(PolyDataToUnstructuredGrid)
 
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})
 
add_executable(PolyDataToUnstructuredGrid MACOSX_BUNDLE PolyDataToUnstructuredGrid.cxx)
 
if(VTK_LIBRARIES)
  target_link_libraries(PolyDataToUnstructuredGrid ${VTK_LIBRARIES})
else()
  target_link_libraries(PolyDataToUnstructuredGrid vtkHybrid vtkWidgets)
endif()

Download and Build PolyDataToUnstructuredGrid

Click here to download PolyDataToUnstructuredGrid. and its CMakeLists.txt file.

Once the tarball PolyDataToUnstructuredGrid.tar has been downloaded and extracted,

cd PolyDataToUnstructuredGrid/build 
  • If VTK is installed:
cmake ..
  • If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:
cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./PolyDataToUnstructuredGrid

WINDOWS USERS PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.