KdTree

vtk-examples/Cxx/DataStructures/KdTree

Description¶

This example demonstrates how to use vtkKdTree to build a tree from a vtkPoints object. Note that since AddDataSet or SetDataSet were not called, you cannot use GetDataSet.

Question

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

Code¶

KdTree.cxx

#include <vtkDataSetCollection.h>
#include <vtkKdTree.h>
#include <vtkNew.h>
#include <vtkPoints.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};

  vtkNew<vtkPoints> points;
  points->InsertNextPoint(x);
  points->InsertNextPoint(y);
  points->InsertNextPoint(z);

  // Create the tree
  vtkNew<vtkKdTree> kDTree;
  kDTree->BuildLocatorFromPoints(points);

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

  auto pointCoordinates = [](double* pt) {
    std::cout << "Coordinates: " << pt[0] << " " << pt[1] << " " << pt[2]
              << std::endl;
  };

  // Find the closest point to TestPoint.
  double closestPointDist;
  vtkIdType id = kDTree->FindClosestPoint(
      testPoint, closestPointDist); // vtkKdTree::FindClosestPoint: must build
                                    // locator first
  std::cout << "Test Point ";
  pointCoordinates(testPoint);
  std::cout << "The closest point is point " << id << std::endl;
  // Get the closest point in the KD Tree from the point data.
  std::cout << "Closest point ";
  pointCoordinates(points->GetPoint(id));
  std::cout << "Distance: " << closestPointDist << std::endl;

  return EXIT_SUCCESS;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(KdTree)

find_package(VTK COMPONENTS 
)

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

Download and Build KdTree¶

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

cd KdTree/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:

./KdTree

WINDOWS USERS

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