VTK/Examples/Cxx/Points/ExtractCluster

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VTK Examples Baseline Points TestExtractClusters.png

This example extracts clusters of points. The points lie on spheres that are randomly placed. Each cluster has a different color. The number of extracted clusters may be less that the number of random spheres, if the points on one sphere are within the specified distance of points on another sphere. NOTE: The classes used in this example require vtk 7.1 or later.

ExtractClusters.cxx

#include <vtkSmartPointer.h>

#include <vtkEuclideanClusterExtraction.h>
#include <vtkPointSource.h>
#include <vtkAppendPolyData.h>
#include <vtkSphereSource.h>
#include <vtkGlyph3D.h>

#include <vtkLookupTable.h>

#include <vtkMath.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkCamera.h>

int main (int, char *[])
{
  vtkMath::RandomSeed(4355412); // for test result consistency
  double limits = 10;
  double radius = .5;

  vtkSmartPointer<vtkAppendPolyData> append =
    vtkSmartPointer<vtkAppendPolyData>::New();
  for (unsigned i = 0; i < 30; ++i)
    {
    vtkSmartPointer<vtkPointSource> points =
      vtkSmartPointer<vtkPointSource>::New();
    points->SetNumberOfPoints(800);
    points->SetRadius(2.5 * radius);
    points->SetCenter(vtkMath::Random(-limits, limits),
                      vtkMath::Random(-limits, limits),
                      vtkMath::Random(-limits, limits));
    points->SetDistributionToShell();

    append->AddInputConnection(points->GetOutputPort());
    }

  vtkSmartPointer<vtkEuclideanClusterExtraction> cluster =
    vtkSmartPointer<vtkEuclideanClusterExtraction>::New();
  cluster->SetInputConnection(append->GetOutputPort());
  cluster->SetExtractionModeToAllClusters();
  cluster->SetRadius(radius);
  cluster->ColorClustersOn();
  cluster->Update();                 

  std::cout << "Found " << cluster->GetNumberOfExtractedClusters()
            << " clusters within radius " << radius << std::endl;

  // Create a lookup table to map point data to colors
  vtkSmartPointer<vtkLookupTable> lut =
    vtkSmartPointer<vtkLookupTable>::New();
  int tableSize = cluster->GetNumberOfExtractedClusters();
  lut->SetNumberOfTableValues(tableSize);
  lut->Build();

  // Fill in the lookup table
  for (unsigned int i = 0; i < tableSize; ++i)
    {
    lut->SetTableValue(i,
                       vtkMath::Random(.25, 1.0),
                       vtkMath::Random(.25, 1.0),
                       vtkMath::Random(.25, 1.0),
                       1.0);
    }

  vtkSmartPointer<vtkSphereSource> sphere =
    vtkSmartPointer<vtkSphereSource>::New();
  sphere->SetRadius(radius / 2.0);

  vtkSmartPointer<vtkGlyph3D> glyphs =
    vtkSmartPointer<vtkGlyph3D>::New();
  glyphs->SetInputConnection(cluster->GetOutputPort());
  glyphs->SetSourceConnection(sphere->GetOutputPort());
  glyphs->ScalingOff();
  glyphs->Update();

  vtkSmartPointer<vtkPolyDataMapper> mapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(glyphs->GetOutputPort());
  mapper->SetScalarRange(0, tableSize - 1);
  mapper->SetLookupTable(lut);

  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
  
  // Create graphics stuff
  //
  vtkSmartPointer<vtkRenderer> ren1 =
    vtkSmartPointer<vtkRenderer>::New();
  ren1->SetBackground(.3, .4, .6);

  vtkSmartPointer<vtkRenderWindow> renWin =
    vtkSmartPointer<vtkRenderWindow>::New();
  renWin->AddRenderer(ren1);
  renWin->SetSize(640, 512);

  vtkSmartPointer<vtkRenderWindowInteractor> iren =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  iren->SetRenderWindow(renWin);
  
  // Add the actors to the renderer
  //
  ren1->AddActor(actor);

  // Generate an interesting view
  //
  ren1->ResetCamera();
  ren1->GetActiveCamera()->Azimuth(120);
  ren1->GetActiveCamera()->Elevation(30);
  ren1->GetActiveCamera()->Dolly(1.5);
  ren1->ResetCameraClippingRange();

  iren->Initialize();
  iren->Start();

  return EXIT_SUCCESS;
}

Please try the new VTKExamples website.

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(ExtractCluster)

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

add_executable(ExtractCluster MACOSX_BUNDLE ExtractCluster.cxx)

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

Download and Build ExtractCluster

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

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

cd ExtractCluster/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:

./ExtractCluster

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.