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PointLocatorFindPointsWithinRadiusDemo

Repository source: PointLocatorFindPointsWithinRadiusDemo

Description

This example uses vtkPointLocator to find all points within a given radius. The example generates "n" spheres and finds all the points within the radius of the spheres. The input vtkPolyData's vtkPointData is set the the radius value of each sphere.

The example takes one or two arguments. The first argument specifies the input file that contains vtkPolyData. The second optional argument specifies the number of radii use. If the number is < 6, the vtkSphereSource will be displayed as concentric translucent spheres.

The image was produced with this command:

PointLocatorFindPointsWithinRadius dragon.ply 10

To see the translucent spheres run:

PointLocatoFindPointsWithinRadius dragon.ply

Info

See other locator demos: KDTreeFindPointsWithinRadiusDemo, OctreeFindPointsWithinRadiusDemo, StaticLocatorFindPointsWithinRadiusDemo

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

PointLocatorFindPointsWithinRadiusDemo.cxx

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

#include <vtkDoubleArray.h>
#include <vtkIdList.h>
#include <vtkPointData.h>
#include <vtkPointLocator.h>
#include <vtkPolyData.h>

#include <vtkLookupTable.h>
#include <vtkNamedColors.h>
#include <vtksys/SystemTools.hxx>

// Readers
#include <vtkBYUReader.h>
#include <vtkOBJReader.h>
#include <vtkPLYReader.h>
#include <vtkPolyDataReader.h>
#include <vtkSTLReader.h>
#include <vtkXMLPolyDataReader.h>

#include <vtkSphereSource.h>

#include <algorithm> // For transform()
#include <array>
#include <cctype> // For to_lower
#include <iostream>
#include <string> // For find_last_of()

namespace {
vtkSmartPointer<vtkPolyData> ReadPolyData(std::string const& fileName);

// Templated join which can be used on any combination
//  of streams, and a container of base types.
template <typename TStream, typename TContainer, typename TSeparator>
TStream& join(TStream& stream, TContainer const& cont,
              TSeparator const& separator)
{
  auto sep = false;
  for (auto const& p : cont)
  {
    if (sep)
      stream << separator;
    else
    {
      sep = true;
    }
    stream << p;
  }
  // As a convenience, return a reference to the passed stream.
  return stream;
}

} // namespace

int main(int argc, char* argv[])
{
  if (argc < 2)
  {
    std::cout << "Usage: " << argv[0] << " dragon.ply [number of radii] "
              << std::endl;
    return EXIT_FAILURE;
  }

  int numberOfRadii = 5;
  if (argc > 2)
  {
    numberOfRadii = std::atoi(argv[2]);
  }
  // Read the polydata
  auto polyData = ReadPolyData(argv[1]);

  // Compute bounds and range
  std::array<double, 6> bounds;
  polyData->GetBounds(bounds.data());
  std::cout << "Bounds: ";
  join(std::cout, bounds, ", ") << std::endl;
  std::array<double, 3> range;
  range[0] = bounds[1] - bounds[0];
  range[1] = bounds[3] - bounds[2];
  range[2] = bounds[5] - bounds[4];
  std::cout << "Range: ";
  join(std::cout, range, ", ") << std::endl;

  // double maxRange = std::max({range[0], range[1], range[2]});
  double minRange = std::min({range[0], range[1], range[2]});

  // Define a sphere at one edge of bounding box
  vtkNew<vtkSphereSource> sphereSource;
  sphereSource->SetCenter(range[0] / 2.0 + bounds[0],
                          range[1] / 2.0 + bounds[2], bounds[5]);
  sphereSource->SetRadius(minRange);
  sphereSource->SetPhiResolution(31);
  sphereSource->SetThetaResolution(31);
  sphereSource->SetStartPhi(90.0);
  sphereSource->Update();

  // Initialize the locator
  vtkNew<vtkPointLocator> pointTree;
  pointTree->SetDataSet(polyData);
  pointTree->BuildLocator();

  // Compute the radius for each call to FindPointsWithinRadius
  std::vector<double> radii;
  double radiiStart = .25 * sphereSource->GetRadius();
  double radiiEnd = 1.0 * sphereSource->GetRadius();
  double radiiDelta = (radiiEnd - radiiStart) / (numberOfRadii - 1);

  for (int r = 0; r < numberOfRadii; ++r)
  {
    radii.push_back(radiiStart + radiiDelta * r);
  }

  // Create an array to hold the scalar point data
  vtkNew<vtkDoubleArray> scalars;
  scalars->SetNumberOfComponents(1);
  scalars->SetNumberOfTuples(polyData->GetNumberOfPoints());
  scalars->FillComponent(0, 0.0);

  // Process each radii from largest to smallest
  for (std::vector<double>::reverse_iterator rIter = radii.rbegin();
       rIter != radii.rend(); ++rIter)
  {
    vtkNew<vtkIdList> result;
    pointTree->FindPointsWithinRadius(*rIter, sphereSource->GetCenter(),
                                      result);
    vtkIdType k = result->GetNumberOfIds();
    std::cout << k << " points within " << *rIter << " of "
              << sphereSource->GetCenter()[0] << ", "
              << sphereSource->GetCenter()[1] << ", "
              << sphereSource->GetCenter()[2] << std::endl;
    // Store the distance in the points withnin the current radius
    for (vtkIdType i = 0; i < k; i++)
    {
      vtkIdType point_ind = result->GetId(i);
      scalars->SetTuple1(point_ind, *rIter);
    }
  }
  polyData->GetPointData()->SetScalars(scalars);

  // Visualize
  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkRenderer> renderer;

  vtkNew<vtkLookupTable> lut;
  lut->SetHueRange(.667, 0.0);
  lut->SetNumberOfTableValues(radii.size() + 1);
  lut->SetRange(*radii.begin(), *radii.rbegin());
  lut->Build();

  // Create a transluscent sphere for each radii
  if (radii.size() < 6)
  {
    for (std::vector<double>::reverse_iterator rIter = radii.rbegin();
         rIter != radii.rend(); ++rIter)
    {
      vtkNew<vtkSphereSource> radiiSource;
      radiiSource->SetPhiResolution(31);
      radiiSource->SetThetaResolution(31);
      radiiSource->SetStartPhi(90.0);
      radiiSource->SetRadius(*rIter);
      radiiSource->SetCenter(range[0] / 2.0 + bounds[0],
                             range[1] / 2.0 + bounds[2], bounds[5]);

      vtkNew<vtkPolyDataMapper> radiiMapper;
      radiiMapper->SetInputConnection(radiiSource->GetOutputPort());

      vtkNew<vtkProperty> backProp;
      backProp->SetDiffuseColor(colors->GetColor3d("LightGrey").GetData());

      vtkNew<vtkActor> radiiActor;
      radiiActor->SetMapper(radiiMapper);
      radiiActor->GetProperty()->SetDiffuseColor(
          colors->GetColor3d("White").GetData());
      radiiActor->GetProperty()->SetOpacity(.1);
      radiiActor->SetBackfaceProperty(backProp);

      renderer->AddActor(radiiActor);
    }
  }

  // Display the original poly data
  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputData(polyData);
  mapper->SetLookupTable(lut);
  mapper->SetScalarRange(*radii.begin(), *radii.rbegin());

  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);
  actor->GetProperty()->SetDiffuseColor(
      colors->GetColor3d("Crimson").GetData());
  actor->GetProperty()->SetInterpolationToFlat();

  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->SetSize(640, 480);
  renderWindow->AddRenderer(renderer);

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("BurlyWood").GetData());
  renderer->UseHiddenLineRemovalOn();
  renderWindow->SetWindowName("PointLocatorFindPointsWithinRadiusDemo");

  renderWindow->Render();

  // Pick a good view
  renderer->GetActiveCamera()->Azimuth(-30);
  renderer->GetActiveCamera()->Elevation(30);
  renderer->GetActiveCamera()->Dolly(1.25);
  renderer->ResetCameraClippingRange();
  renderWindow->Render();

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

namespace {
vtkSmartPointer<vtkPolyData> ReadPolyData(std::string const& fileName)
{
  vtkSmartPointer<vtkPolyData> polyData;
  std::string extension = "";
  if (fileName.find_last_of(".") != std::string::npos)
  {
    extension = fileName.substr(fileName.find_last_of("."));
  }
  // Make the extension lowercase
  std::transform(extension.begin(), extension.end(), extension.begin(),
                 ::tolower);
  if (extension == ".ply")
  {
    auto reader = vtkSmartPointer<vtkPLYReader>::New();
    reader->SetFileName(fileName.c_str());
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".vtp")
  {
    auto reader = vtkSmartPointer<vtkXMLPolyDataReader>::New();
    reader->SetFileName(fileName.c_str());
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".obj")
  {
    auto reader = vtkSmartPointer<vtkOBJReader>::New();
    reader->SetFileName(fileName.c_str());
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".stl")
  {
    auto reader = vtkSmartPointer<vtkSTLReader>::New();
    reader->SetFileName(fileName.c_str());
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".vtk")
  {
    auto reader = vtkSmartPointer<vtkPolyDataReader>::New();
    reader->SetFileName(fileName.c_str());
    reader->Update();
    polyData = reader->GetOutput();
  }
  else if (extension == ".g")
  {
    auto reader = vtkSmartPointer<vtkBYUReader>::New();
    reader->SetGeometryFileName(fileName.c_str());
    reader->Update();
    polyData = reader->GetOutput();
  }
  else
  {
    // Return a polydata sphere if the extension is unknown.
    auto source = vtkSmartPointer<vtkSphereSource>::New();
    source->SetThetaResolution(20);
    source->SetPhiResolution(11);
    source->Update();
    polyData = source->GetOutput();
  }
  return polyData;
}
} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(PointLocatorFindPointsWithinRadiusDemo)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  CommonDataModel
  FiltersSources
  IOGeometry
  IOLegacy
  IOPLY
  IOXML
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "PointLocatorFindPointsWithinRadiusDemo: 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(PointLocatorFindPointsWithinRadiusDemo MACOSX_BUNDLE PointLocatorFindPointsWithinRadiusDemo.cxx )
  target_link_libraries(PointLocatorFindPointsWithinRadiusDemo PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS PointLocatorFindPointsWithinRadiusDemo
  MODULES ${VTK_LIBRARIES}
)

Download and Build PointLocatorFindPointsWithinRadiusDemo

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

cd PointLocatorFindPointsWithinRadiusDemo/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:

./PointLocatorFindPointsWithinRadiusDemo

WINDOWS USERS

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