PolyDataConnectivityFilter LargestRegion

VTKExamples/Cxx/PolyData/PolyDataConnectivityFilter_LargestRegion

Description

This example keeps the largest connected region of a mesh. Note that this is based on the number of points, not the actual area of the region.

  • Contributed by: Jinyoung Hwang

Code

PolyDataConnectivityFilter_LargestRegion.cxx

#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkPolyDataConnectivityFilter.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkProperty.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkAppendPolyData.h>

int main(int, char *[])
{
  // Small sphere
  vtkSmartPointer<vtkSphereSource> sphereSource1 = 
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource1->Update();

  // Large sphere
  vtkSmartPointer<vtkSphereSource> sphereSource2 = 
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource2->SetRadius(10);
  sphereSource2->SetCenter(25,0,0);
  sphereSource2->SetThetaResolution(10);
  sphereSource2->SetPhiResolution(10);
  sphereSource2->Update();

  vtkSmartPointer<vtkAppendPolyData> appendFilter = 
    vtkSmartPointer<vtkAppendPolyData>::New();
  appendFilter->AddInputConnection(sphereSource1->GetOutputPort());
  appendFilter->AddInputConnection(sphereSource2->GetOutputPort());
  appendFilter->Update();

  vtkSmartPointer<vtkPolyDataConnectivityFilter> connectivityFilter = 
    vtkSmartPointer<vtkPolyDataConnectivityFilter>::New();
  connectivityFilter->SetInputConnection(appendFilter->GetOutputPort());
  connectivityFilter->SetExtractionModeToLargestRegion(); 
  connectivityFilter->Update();

  // Create a mapper and actor for original data
  vtkSmartPointer<vtkPolyDataMapper> originalMapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  originalMapper->SetInputConnection(appendFilter->GetOutputPort());
  originalMapper->Update();

  vtkSmartPointer<vtkActor> originalActor = 
    vtkSmartPointer<vtkActor>::New();
  originalActor->SetMapper(originalMapper);

  // Create a mapper and actor for extracted data
  vtkSmartPointer<vtkPolyDataMapper> extractedMapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  extractedMapper->SetInputConnection(connectivityFilter->GetOutputPort());
  extractedMapper->Update();

  vtkSmartPointer<vtkActor> extractedActor = 
    vtkSmartPointer<vtkActor>::New();
  extractedActor->GetProperty()->SetColor(1,0,0);
  extractedActor->SetMapper(extractedMapper);

  // Visualization
  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  renderer->AddActor(originalActor);
  renderer->AddActor(extractedActor);

  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);

  vtkSmartPointer<vtkRenderWindowInteractor> interactor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  interactor->SetRenderWindow(renderWindow);
  interactor->Initialize();
  interactor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(PolyDataConnectivityFilter_LargestRegion)

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

add_executable(PolyDataConnectivityFilter_LargestRegion MACOSX_BUNDLE PolyDataConnectivityFilter_LargestRegion.cxx)

target_link_libraries(PolyDataConnectivityFilter_LargestRegion ${VTK_LIBRARIES})

Download and Build PolyDataConnectivityFilter_LargestRegion

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

cd PolyDataConnectivityFilter_LargestRegion/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:

./PolyDataConnectivityFilter_LargestRegion

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.