PolyDataConnectivityFilter LargestRegion

VTKExamples/Cxx/PolyData/PolyDataConnectivityFilter_LargestRegion


Description

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

The original vtkPolyData is red, on top. The extracted region is yellow, on the bottom.

Note

Contributed by: Jinyoung Hwang

Code

PolyDataConnectivityFilter_LargestRegion.cxx

#include <vtkSmartPointer.h>
#include <vtkPolyDataConnectivityFilter.h>

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

#include <vtkNamedColors.h>

int main(int, char *[])
{
  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  // Small sphere
  vtkSmartPointer<vtkSphereSource> sphereSource1 = 
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource1->SetRadius(5);

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

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

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

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

  vtkSmartPointer<vtkActor> originalActor = 
    vtkSmartPointer<vtkActor>::New();
  originalActor->SetMapper(originalMapper);
  originalActor->GetProperty()->SetColor(colors->GetColor3d("Tomato").GetData());

  // 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(colors->GetColor3d("Banana").GetData());
  extractedActor->SetMapper(extractedMapper);
  extractedActor->SetPosition(0,-20,0);

  // Visualization
  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  renderer->AddActor(originalActor);
  renderer->AddActor(extractedActor);
  renderer->GradientBackgroundOn();
  renderer->SetBackground (colors->GetColor3d("Gold").GetData());
  renderer->SetBackground2 (colors->GetColor3d("Silver").GetData());

  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

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

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