\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)

CGAL 4.8 - Point Set Processing

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Point_set_processing_3/edges_example.cpp
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/vcm_estimate_edges.h>
#include <CGAL/property_map.h>
#include <CGAL/IO/read_off_points.h>
#include <utility> // defines std::pair
#include <vector>
#include <fstream>
#include <boost/foreach.hpp>
// 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;
typedef std::vector<PointVectorPair> PointList;
typedef CGAL::cpp11::array<double,6> Covariance;
int main (int , char**) {
// Reads a .xyz point set file in points[].
std::list<PointVectorPair> points;
std::ifstream stream("data/fandisk.off");
if (!stream ||
!CGAL::read_off_points(stream,
std::back_inserter(points),
CGAL::First_of_pair_property_map<PointVectorPair>()))
{
std::cerr << "Error: cannot read file data/fandisk.off" << std::endl;
return EXIT_FAILURE;
}
// Estimates covariance matrices per points.
double R = 0.2,
r = 0.1;
std::vector<Covariance> cov;
CGAL::First_of_pair_property_map<PointVectorPair> point_pmap;
CGAL::compute_vcm(points.begin(), points.end(), point_pmap, cov, R, r, Kernel());
// Find the points on the edges.
// Note that this step is not expensive and can be done several time to get better results
double threshold = 0.16;
std::ofstream output("points_on_edges.xyz");
int i = 0;
BOOST_FOREACH(const PointVectorPair& p, points)
{
if (CGAL::vcm_is_on_feature_edge(cov[i], threshold))
output << p.first << "\n";
++i;
}
return 0;
}