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MeshQuality

vtk-examples/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.

Other languages

See (Java)

Question

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Code

MeshQuality.cxx

#include <vtkActor.h>
#include <vtkCellData.h>
#include <vtkColorSeries.h>
#include <vtkDataSet.h>
#include <vtkDoubleArray.h>
#include <vtkLookupTable.h>
#include <vtkMeshQuality.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSphereSource.h>
#include <vtkTriangleFilter.h>

void MakeLUT(vtkLookupTable* lut)
{
  // Make the lookup table.
  vtkNew<vtkColorSeries> colorSeries;
  // Select a color scheme.
  int colorSeriesEnum;
  colorSeriesEnum = colorSeries->BREWER_DIVERGING_BROWN_BLUE_GREEN_9;
  // colorSeriesEnum = colorSeries->BREWER_DIVERGING_SPECTRAL_10;
  // colorSeriesEnum = colorSeries->BREWER_DIVERGING_SPECTRAL_3;
  // colorSeriesEnum = colorSeries->BREWER_DIVERGING_PURPLE_ORANGE_9;
  // colorSeriesEnum = colorSeries->BREWER_SEQUENTIAL_BLUE_PURPLE_9;
  // colorSeriesEnum = colorSeries->BREWER_SEQUENTIAL_BLUE_GREEN_9;
  // colorSeriesEnum = colorSeries->BREWER_QUALITATIVE_SET3;
  // colorSeriesEnum = colorSeries->CITRUS;
  colorSeries->SetColorScheme(colorSeriesEnum);

  colorSeries->BuildLookupTable(lut);
  lut->SetNanColor(1, 0, 0, 1);
}

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkSphereSource> sphereSource;
  sphereSource->Update();

  vtkNew<vtkTriangleFilter> triangleFilter;
  triangleFilter->SetInputConnection(sphereSource->GetOutputPort());
  triangleFilter->Update();

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

  vtkNew<vtkMeshQuality> qualityFilter;
  qualityFilter->SetInputData(mesh);
  qualityFilter->SetTriangleQualityMeasureToArea();
  qualityFilter->Update();

  auto qualityArray = dynamic_cast<vtkDoubleArray*>(
      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;
  }

  vtkNew<vtkPolyData> polydata;
  polydata->ShallowCopy(qualityFilter->GetOutput());

  // Visualize

  vtkNew<vtkLookupTable> lut;
  MakeLUT(lut);
  lut->SetTableRange(polydata->GetScalarRange());
  lut->IndexedLookupOff();

  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputData(polydata);
  mapper->SetScalarRange(polydata->GetScalarRange());
  mapper->SetLookupTable(lut);

  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);

  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("MeshQuality");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());

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

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(MeshQuality)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersCore
  vtkFiltersSources
  vtkFiltersVerdict
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping MeshQuality: ${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(MeshQuality MACOSX_BUNDLE MeshQuality.cxx )
  target_link_libraries(MeshQuality PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(MeshQuality MACOSX_BUNDLE MeshQuality.cxx )
  target_link_libraries(MeshQuality PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS MeshQuality
    MODULES ${VTK_LIBRARIES}
    )
endif ()

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.