Point_set_processing_3/scale_estimation_example.cpp

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/IO/read_xyz_points.h>

#include <CGAL/estimate_scale.h>
#include <CGAL/jet_smooth_point_set.h>
#include <CGAL/grid_simplify_point_set.h>

#include <CGAL/Timer.h>
#include <CGAL/Memory_sizer.h>

#include <vector>
#include <fstream>

// Concurrency
#ifdef CGAL_LINKED_WITH_TBB
typedef CGAL::Parallel_tag Concurrency_tag;
#else
typedef CGAL::Sequential_tag Concurrency_tag;
#endif

// Types
typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef Kernel::FT FT;
typedef Kernel::Point_3 Point_3;

int main (int argc, char** argv)
{

  const char* fname = (argc>1)?argv[1]:"data/sphere_20k.xyz";
  
  CGAL::Timer task_timer;
  
  std::vector<Point_3> points;  
  std::ifstream stream(fname);

  // read input
  if (!(stream
        && CGAL::read_xyz_points(stream, std::back_inserter(points))))
    {
      std::cerr << "Error: can't read input file" << std::endl;
      return EXIT_FAILURE;
    }
          
  // estimate k scale
  task_timer.start();
  std::size_t k_scale = CGAL::estimate_global_k_neighbor_scale (points);
  task_timer.stop();
  
  // Example: use estimated k as scale for jet smoothing
  CGAL::jet_smooth_point_set<Concurrency_tag>
    (points, static_cast<unsigned int>(k_scale));

  // estimate range scale
  task_timer.start();
  FT range_scale = CGAL::estimate_global_range_scale (points);
  task_timer.stop();

  // Example: use estimated range for grid simplification
  points.erase (CGAL::grid_simplify_point_set (points, range_scale),
                points.end());

  
  // print some informations on runtime
  std::size_t memory = CGAL::Memory_sizer().virtual_size();
  double time = task_timer.time();

  std::cout << "Scales computed in " << time << " second(s) using "
            << (memory>>20) << " MiB of memory:" << std::endl;
  std::cout << " * Global K scale: " << k_scale << std::endl;
  std::cout << " * Global range scale: " << range_scale << std::endl;


  return EXIT_SUCCESS;
}