KdTreePointLocatorClosestPoint

VTKExamples/Cxx/DataStructures/KdTreePointLocatorClosestPoint

Description

This example creates a set of three points, builds a KDTree from them, then demonstrates how to find the closest point to a query point.

Code

KdTreePointLocatorClosestPoint.cxx

#include <vtkSmartPointer.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkIdList.h>
#include <vtkKdTreePointLocator.h>

int main(int, char *[])
{
  // Setup point coordinates
  double x[3] = {1.0, 0.0, 0.0};
  double y[3] = {0.0, 1.0, 0.0};
  double z[3] = {0.0, 0.0, 1.0};

  vtkSmartPointer<vtkPoints> points = 
    vtkSmartPointer<vtkPoints>::New();
  points->InsertNextPoint(x);
  points->InsertNextPoint(y);
  points->InsertNextPoint(z);

  vtkSmartPointer<vtkPolyData> polydata = 
    vtkSmartPointer<vtkPolyData>::New();
  polydata->SetPoints(points);

  // Create the tree
  vtkSmartPointer<vtkKdTreePointLocator> kDTree = 
    vtkSmartPointer<vtkKdTreePointLocator>::New();
  kDTree->SetDataSet(polydata);
  kDTree->BuildLocator();

  double testPoint[3] = {2.0, 0.0, 0.0};

  // Find the closest points to TestPoint
  vtkIdType iD = kDTree->FindClosestPoint(testPoint);
  std::cout << "The closest point is point " << iD << std::endl;

  //Get the coordinates of the closest point
  double closestPoint[3];
  kDTree->GetDataSet()->GetPoint(iD, closestPoint);
  std::cout << "Coordinates: " << closestPoint[0] << " " << closestPoint[1] << " " << closestPoint[2] << std::endl;

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(KdTreePointLocatorClosestPoint)

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

add_executable(KdTreePointLocatorClosestPoint MACOSX_BUNDLE KdTreePointLocatorClosestPoint.cxx )

target_link_libraries(KdTreePointLocatorClosestPoint ${VTK_LIBRARIES})

Download and Build KdTreePointLocatorClosestPoint

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

cd KdTreePointLocatorClosestPoint/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:

./KdTreePointLocatorClosestPoint

WINDOWS USERS

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