CGAL 6.1.1 - Point Set Processing

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Point_set_processing_3/normals_example.cpp
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/compute_average_spacing.h>
#include <CGAL/pca_estimate_normals.h>
#include <CGAL/mst_orient_normals.h>
#include <CGAL/property_map.h>
#include <CGAL/IO/read_points.h>
#include <utility> // defines std::pair
#include <list>
#include <fstream>
// Types
typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef Kernel::Point_3 Point;
typedef Kernel::Vector_3 Vector;
// Point with normal vector stored in a std::pair.
typedef std::pair<Point, Vector> PointVectorPair;
// Concurrency
typedef CGAL::Parallel_if_available_tag Concurrency_tag;
int main(int argc, char*argv[])
{
const std::string fname = (argc>1) ? argv[1] : CGAL::data_file_path("points_3/sphere_1k.xyz");
// Reads a point set file in points[].
std::list<PointVectorPair> points;
if(!CGAL::IO::read_points(fname,
std::back_inserter(points),
CGAL::parameters::point_map(CGAL::First_of_pair_property_map<PointVectorPair>())))
{
std::cerr << "Error: cannot read file " << fname<< std::endl;
return EXIT_FAILURE;
}
// Estimates normals direction.
// Note: pca_estimate_normals() requiresa range of points
// as well as property maps to access each point's position and normal.
const int nb_neighbors = 18; // K-nearest neighbors = 3 rings
if (argc > 2 && std::strcmp(argv[2], "-r") == 0) // Use a fixed neighborhood radius
{
// First compute a spacing using the K parameter
double spacing
= CGAL::compute_average_spacing<Concurrency_tag>
(points, nb_neighbors,
CGAL::parameters::point_map(CGAL::First_of_pair_property_map<PointVectorPair>()));
// Then, estimate normals with a fixed radius
CGAL::pca_estimate_normals<Concurrency_tag>
(points,
0, // when using a neighborhood radius, K=0 means no limit on the number of neighbors returns
CGAL::parameters::point_map(CGAL::First_of_pair_property_map<PointVectorPair>())
.normal_map(CGAL::Second_of_pair_property_map<PointVectorPair>())
.neighbor_radius(2. * spacing)); // use 2*spacing as neighborhood radius
}
else // Use a fixed number of neighbors
{
CGAL::pca_estimate_normals<Concurrency_tag>
(points, nb_neighbors,
CGAL::parameters::point_map(CGAL::First_of_pair_property_map<PointVectorPair>())
.normal_map(CGAL::Second_of_pair_property_map<PointVectorPair>()));
}
// Orients normals.
// Note: mst_orient_normals() requires a range of points
// as well as property maps to access each point's position and normal.
std::list<PointVectorPair>::iterator unoriented_points_begin =
CGAL::mst_orient_normals(points, nb_neighbors,
CGAL::parameters::point_map(CGAL::First_of_pair_property_map<PointVectorPair>())
.normal_map(CGAL::Second_of_pair_property_map<PointVectorPair>()));
// Optional: delete points with an unoriented normal
// if you plan to call a reconstruction algorithm that expects oriented normals.
points.erase(unoriented_points_begin, points.end());
return EXIT_SUCCESS;
}
CGAL::Exact_predicates_inexact_constructions_kernel
Kernel::Point_3
Kernel::Vector_3
CGAL::mst_orient_normals
PointRange::iterator mst_orient_normals(PointRange &points, unsigned int k, const NamedParameters &np=parameters::default_values())
Orients the normals of the range of points using the propagation of a seed orientation through a mini...
Definition: mst_orient_normals.h:610
CGAL::IO::read_points
bool read_points(const std::string &fname, PointOutputIterator output, const NamedParameters &np=parameters::default_values())
reads the point set from an input file.
Definition: read_points.h:89
Kernel
CGAL::First_of_pair_property_map
CGAL::Parallel_if_available_tag
CGAL::Second_of_pair_property_map