CGAL 6.2 - Quadtrees, Octrees, and Orthtrees

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Orthtree/octree_find_nearest_neighbor.cpp
#include <fstream>
#include <iostream>
#include <CGAL/Simple_cartesian.h>
#include <CGAL/Octree.h>
#include <CGAL/Point_set_3.h>
#include <CGAL/Point_set_3/IO.h>
#include <boost/iterator/function_output_iterator.hpp>
// Type Declarations
using Kernel = CGAL::Simple_cartesian<double>;
using Point = Kernel::Point_3;
using Point_set = CGAL::Point_set_3<Point>;
using Point_map = Point_set::Point_map;
using Octree = CGAL::Octree<Kernel, Point_set, Point_map>;
int main(int argc, char** argv) {
// Point set will be used to hold our points
Point_set points;
// Load points from a file.
std::ifstream stream((argc > 1) ? argv[1] : CGAL::data_file_path("points_3/cube.pwn"));
stream >> points;
if (0 == points.number_of_points()) {
std::cerr << "Error: cannot read file" << std::endl;
return EXIT_FAILURE;
}
std::cout << "loaded " << points.number_of_points() << " points" << std::endl;
// Create an octree from the points
Octree octree(points, points.point_map());
// Build the octree
octree.refine(10, 20);
// Find the nearest points to a few locations
std::vector<Point> points_to_find = {
{0, 0, 0},
{1, 1, 1},
{-1, -1, -1},
{-0.46026, -0.25353, 0.32051},
{-0.460261, -0.253533, 0.320513}
};
for (const Point& p : points_to_find)
octree.nearest_k_neighbors
(p, 1, // k=1 to find the single closest point
boost::make_function_output_iterator
([&](const Point_set::Index& nearest)
{
std::cout << "the nearest point to (" << p <<
") is (" << points.point(nearest) << ")" << std::endl;
}));
typename Octree::Sphere s(points_to_find[0], 0.0375);
std::cout << std::endl << "Closest points within the sphere around " << s.center() << " with squared radius of " << s.squared_radius() << ":" << std::endl;
octree.neighbors_within_radius
(s,
boost::make_function_output_iterator
([&](const Point_set::Index& nearest)
{
std::cout << points.point(nearest) << " dist: " << (Point(0, 0, 0) - points.point(nearest)).squared_length() << std::endl;
}));
std::size_t k = 3;
std::cout << std::endl << "The up to " << k << " closest points to(" << s.center() << ") within a squared radius of " << s.squared_radius() << " are:" << std::endl;
octree.nearest_k_neighbors_within_radius
(s, k,
boost::make_function_output_iterator
([&](const Point_set::Index& nearest)
{
std::cout << "(" << points.point(nearest) << " dist: " << (Point(0, 0, 0) - points.point(nearest)).squared_length() << std::endl;
}));
return EXIT_SUCCESS;
}
CGAL::Orthtree
A data structure using an axis-aligned hyperrectangle decomposition of dD space for efficient access ...
Definition: Orthtree.h:118
CGAL::Point_set_3
Kernel::Point_3
Kernel
CGAL::Simple_cartesian