# KdTreePointLocatorClosestPoint

vtk-examples/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

### Code¶

KdTreePointLocatorClosestPoint.cxx

#include <vtkIdList.h>
#include <vtkKdTreePointLocator.h>
#include <vtkNew.h>
#include <vtkPoints.h>
#include <vtkPolyData.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);

vtkNew<vtkPolyData> polydata;
polydata->SetPoints(points);

// Create the tree
vtkNew<vtkKdTreePointLocator> kDTree;
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 3.12 FATAL_ERROR)

project(KdTreePointLocatorClosestPoint)

find_package(VTK COMPONENTS
CommonCore
CommonDataModel
)

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


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.