VTK/Examples/Cxx/PolyData/GeometryFilter

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This example demonstrates how to convert an unstructured grid to a polydata. Currently nothing is done with the resulting polydata. If someone has a good data set that demonstrates the conversion, please let us know.

GeometryFilter.cxx

#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkPolyData.h>
#include <vtkUnstructuredGrid.h>
#include <vtkCellArray.h>
#include <vtkGeometryFilter.h>
#include <vtkPointSource.h>

int main(int, char *[])
{ 
  vtkSmartPointer<vtkUnstructuredGrid> unstructuredGrid = 
    vtkSmartPointer<vtkUnstructuredGrid>::New();
  
  vtkSmartPointer<vtkGeometryFilter> geometryFilter = 
    vtkSmartPointer<vtkGeometryFilter>::New();
#if VTK_MAJOR_VERSION <= 5
  geometryFilter->SetInput(unstructuredGrid);
#else
  geometryFilter->SetInputData(unstructuredGrid);
#endif
  geometryFilter->Update(); 
 
  vtkPolyData* polydata = geometryFilter->GetOutput();

  std::cout << "Output has " << polydata->GetNumberOfPoints() << " points." << std::endl;

  return EXIT_SUCCESS;
}

Please try the new VTKExamples website.

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(GeometryFilter)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(GeometryFilter MACOSX_BUNDLE GeometryFilter.cxx)

if(VTK_LIBRARIES)
  target_link_libraries(GeometryFilter ${VTK_LIBRARIES})
else()
  target_link_libraries(GeometryFilter vtkHybrid vtkWidgets)
endif()

Download and Build GeometryFilter

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

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

cd GeometryFilter/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:

./GeometryFilter

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.

Perform a Delaunay triangulation on a sphere. Show it in wireframe so one can see all of the internal edges. Then run the filter and show that the result is only the outer surface.