MeshQuality

VTKExamples/Cxx/PolyData/MeshQuality


Description

This example uses one of many selectable methods to determine the quality of a mesh. In this case, we have selected to use the area of the triangles. We show how to retrieve the quality metric computed on each triangle after the process is completed.

Code

MeshQuality.cxx

#include <vtkVersion.h>
#include <vtkPolyData.h>
#include <vtkPointData.h>
#include <vtkCellData.h>
#include <vtkDoubleArray.h>
#include <vtkDataSet.h>
#include <vtkMeshQuality.h>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkTriangleFilter.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>

int main(int, char *[])
{
  vtkSmartPointer<vtkSphereSource> sphereSource =
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->Update();

  vtkSmartPointer<vtkTriangleFilter> triangleFilter =
    vtkSmartPointer<vtkTriangleFilter>::New();
  triangleFilter->SetInputConnection(sphereSource->GetOutputPort());
  triangleFilter->Update();

  vtkPolyData* mesh = triangleFilter->GetOutput();
  std::cout << "There are " << mesh->GetNumberOfCells() << " cells." << std::endl;

  vtkSmartPointer<vtkMeshQuality> qualityFilter =
    vtkSmartPointer<vtkMeshQuality>::New();
#if VTK_MAJOR_VERSION <= 5
  qualityFilter->SetInputConnection(mesh->GetProducerPort());
#else
  qualityFilter->SetInputData(mesh);
#endif
  qualityFilter->SetTriangleQualityMeasureToArea();
  qualityFilter->Update();

  vtkSmartPointer<vtkDoubleArray> qualityArray =
    vtkDoubleArray::SafeDownCast(qualityFilter->GetOutput()->GetCellData()->GetArray("Quality"));

  std::cout << "There are " << qualityArray->GetNumberOfTuples() << " values." << std::endl;

  for(vtkIdType i = 0; i < qualityArray->GetNumberOfTuples(); i++)
  {
    double val = qualityArray->GetValue(i);
    std::cout << "value " << i << " : " << val << std::endl;
  }

  vtkSmartPointer<vtkPolyData> polydata =
    vtkSmartPointer<vtkPolyData>::New();
  polydata->ShallowCopy(qualityFilter->GetOutput());

  // Visualize
  vtkSmartPointer<vtkPolyDataMapper> mapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
#if VTK_MAJOR_VERSION <= 5
  mapper->SetInputConnection(polydata->GetProducerPort());
#else
  mapper->SetInputData(polydata);
#endif
  mapper->SetScalarRange(polydata->GetScalarRange());

  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);

  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  renderer->AddActor(actor);
  renderer->SetBackground(.3, .6, .3); // Background color green

  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(MeshQuality)

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

add_executable(MeshQuality MACOSX_BUNDLE MeshQuality.cxx )

target_link_libraries(MeshQuality ${VTK_LIBRARIES})

Download and Build MeshQuality

Click here to download MeshQuality and its CMakeLists.txt file. Once the tarball MeshQuality.tar has been downloaded and extracted,

cd MeshQuality/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:

./MeshQuality

WINDOWS USERS

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