ConvexHullShrinkWrap

VTKExamples/Cxx/PolyData/ConvexHullShrinkWrap

Description

This example creates a point cloud, and a sphere larger than the point cloud which fully contains the cloud. It then "shrink wraps" the sphere onto the points. This produces approximately a convex hull.

Code

ConvexHullShrinkWrap.cxx

#include <vtkSmartPointer.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <vtkGlyph3D.h>
#include <vtkPointSource.h>
#include <vtkSmoothPolyDataFilter.h>
#include <vtkNamedColors.h>

#include <vtkDataSetMapper.h>
#include <vtkActor.h>
#include <vtkProperty.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>

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

  vtkSmartPointer<vtkSphereSource> sphereSource = 
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->SetRadius(10);
  sphereSource->SetPhiResolution(50);
  sphereSource->SetThetaResolution(50);

  vtkSmartPointer<vtkPointSource> pointSource = 
    vtkSmartPointer<vtkPointSource>::New();
  pointSource->SetNumberOfPoints(60);
  pointSource->SetRadius(2);

  vtkSmartPointer<vtkSmoothPolyDataFilter> smoothFilter = 
    vtkSmartPointer<vtkSmoothPolyDataFilter>::New();
  smoothFilter->SetInputConnection(0, sphereSource->GetOutputPort());
  smoothFilter->SetInputConnection(1, pointSource->GetOutputPort());

  vtkSmartPointer<vtkSphereSource> glyphSource = 
    vtkSmartPointer<vtkSphereSource>::New();
  glyphSource->SetRadius(.04);

  vtkSmartPointer<vtkGlyph3D> glyph3D =
    vtkSmartPointer<vtkGlyph3D>::New();
  glyph3D->SetInputConnection(pointSource->GetOutputPort());
  glyph3D->SetSourceConnection(glyphSource->GetOutputPort());
  glyph3D->ScalingOff();

  vtkSmartPointer<vtkDataSetMapper> glyph3DMapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  glyph3DMapper->SetInputConnection(glyph3D->GetOutputPort());
  glyph3DMapper->ScalarVisibilityOff();

  vtkSmartPointer<vtkActor> glyph3DActor =
    vtkSmartPointer<vtkActor>::New();
  glyph3DActor->SetMapper(glyph3DMapper);
  glyph3DActor->GetProperty()->SetColor(
    namedColors->GetColor3d("Banana").GetData());

  vtkSmartPointer<vtkDataSetMapper> mapper = 
    vtkSmartPointer<vtkDataSetMapper>::New();
  mapper->SetInputConnection(smoothFilter->GetOutputPort());
  mapper->ScalarVisibilityOff();

  // Create an actor for the surface
  vtkSmartPointer<vtkActor> actor = 
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
  actor->GetProperty()->SetDiffuseColor(
    namedColors->GetColor3d("Tomato").GetData());
  actor->GetProperty()->SetEdgeColor(
    namedColors->GetColor3d("IvoryBlack").GetData());
  actor->GetProperty()->SetOpacity(1.0);
  actor->GetProperty()->EdgeVisibilityOff();

  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> interactor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  interactor->SetRenderWindow(renderWindow);

  renderer->AddActor(actor);
  renderer->AddActor(glyph3DActor);
  renderer->SetBackground(namedColors->GetColor3d("SlateGray").GetData());

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

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(ConvexHullShrinkWrap)

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

add_executable(ConvexHullShrinkWrap MACOSX_BUNDLE ConvexHullShrinkWrap.cxx )

target_link_libraries(ConvexHullShrinkWrap ${VTK_LIBRARIES})

Download and Build ConvexHullShrinkWrap

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

cd ConvexHullShrinkWrap/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:

./ConvexHullShrinkWrap

WINDOWS USERS

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