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

CGAL 4.8 - 3D Alpha Shapes

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Alpha_shapes_3/ex_alpha_shapes_with_fast_location_3.cpp
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Delaunay_triangulation_3.h>
#include <CGAL/Alpha_shape_3.h>
#include <fstream>
#include <list>
#include <cassert>
typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Alpha_shape_vertex_base_3<K> Vb;
typedef CGAL::Alpha_shape_cell_base_3<K> Fb;
typedef CGAL::Triangulation_data_structure_3<Vb,Fb> Tds;
typedef CGAL::Delaunay_triangulation_3<K,Tds,CGAL::Fast_location> Delaunay;
typedef CGAL::Alpha_shape_3<Delaunay> Alpha_shape_3;
typedef K::Point_3 Point;
typedef Alpha_shape_3::Alpha_iterator Alpha_iterator;
typedef Alpha_shape_3::NT NT;
int main()
{
Delaunay dt;
std::ifstream is("./data/bunny_1000");
int n;
is >> n;
Point p;
std::cout << n << " points read" << std::endl;
for( ; n>0 ; n--) {
is >> p;
dt.insert(p);
}
std::cout << "Delaunay computed." << std::endl;
// compute alpha shape
Alpha_shape_3 as(dt);
std::cout << "Alpha shape computed in REGULARIZED mode by defaut."
<< std::endl;
// find optimal alpha values
Alpha_shape_3::NT alpha_solid = as.find_alpha_solid();
Alpha_iterator opt = as.find_optimal_alpha(1);
std::cout << "Smallest alpha value to get a solid through data points is "
<< alpha_solid << std::endl;
std::cout << "Optimal alpha value to get one connected component is "
<< *opt << std::endl;
as.set_alpha(*opt);
assert(as.number_of_solid_components() == 1);
return 0;
}