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 <vtkDoubleArray.h>
#include <vtkLookupTable.h>
#include <vtkMeshQuality.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSphereSource.h>
#include <vtkTriangleFilter.h>

#include <iostream>
#include <string>

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 3.12 FATAL_ERROR)

project(MeshQuality)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "MeshQuality: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
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}
)

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.