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.

Question

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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 3.3 FATAL_ERROR)

project(KdTreePointLocatorClosestPoint)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel QUIET)
if (NOT VTK_FOUND)
  message("Skipping KdTreePointLocatorClosestPoint: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(KdTreePointLocatorClosestPoint MACOSX_BUNDLE KdTreePointLocatorClosestPoint.cxx )
  target_link_libraries(KdTreePointLocatorClosestPoint PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(KdTreePointLocatorClosestPoint MACOSX_BUNDLE KdTreePointLocatorClosestPoint.cxx )
  target_link_libraries(KdTreePointLocatorClosestPoint PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS KdTreePointLocatorClosestPoint
    MODULES ${VTK_LIBRARIES}
    )
endif () 

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.