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I try to use triangulated surface mesh simplification of cgal. I used Garland&Heckbert Simplification to simplify my mesh, but it tooks so long. My data has 50000 nv, 165883 ne and 109521 nf, which needs almost 30mins with 0.2 stop_ratio. Is the runtime cost reasonable? I also check whether the input mesh is valid by using CGAL::is_valid_polygon_mesh. It is valid. how can i solve this problem? Thank you so much...

the runtime cost of mesh with 165883 edges

the runtime cost of mesh with 8282 edges

enter code here

#include <fstream>
#include <iostream>
#include <iterator>
#include <vector>
#include "gltf-loader.h"
#define TINYGLTF_NO_STB_IMAGE_WRITE
#define TINYGLTF_IMPLEMENTATION
#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "tiny_gltf.h"

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Simple_cartesian.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/draw_surface_mesh.h>
#include <CGAL/draw_polygon_2.h>

#include <CGAL/Polygon_mesh_processing/repair.h>
#include <CGAL/Polygon_mesh_processing/IO/polygon_mesh_io.h>
#include <CGAL/boost/graph/iterator.h>
#include <CGAL/Polygon_2.h>

#include <CGAL/Surface_mesh_simplification/edge_collapse.h>
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Count_ratio_stop_predicate.h>
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Bounded_normal_change_placement.h>
#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/GarlandHeckbert_policies.h>
#include <CGAL/Polyhedron_3.h>
#include <CGAL/Polygon_mesh_processing/stitch_borders.h>
#include <chrono>
#include <vector>


using namespace example;

namespace PMP = CGAL::Polygon_mesh_processing;
namespace NP = CGAL::parameters;
//typedef CGAL::Exact_predicates_inexact_constructions_kernel     K;
typedef CGAL::Simple_cartesian<double>                          K;

typedef CGAL::Surface_mesh<K::Point_3>                               CGAL_Mesh;
typedef CGAL_Mesh::Vertex_index                                      vertex_descriptor;
typedef CGAL_Mesh::Face_index                                        face_descriptor;
namespace SMS = CGAL::Surface_mesh_simplification;
CGAL_Mesh inital_mesh;

    const char* filename = "C:\\Users\\Administrator\\source\\repos\\CMakeProject4\\CMakeProject4\\input.off";
 
   
    if (!PMP::IO::read_polygon_mesh(filename, inital_mesh) || CGAL::is_empty(inital_mesh))
    {
        std::cerr << "Invalid input." << std::endl;
        return 1;
    }

 std::chrono::steady_clock::time_point start_time = std::chrono::steady_clock::now();
   double stop_ratio = 0.2;

    std::cout << "start edge collages." << std::endl;
    SMS::Count_ratio_stop_predicate<CGAL_Mesh> stop(stop_ratio);

    typedef typename SMS::GarlandHeckbert_policies<CGAL_Mesh, K>          GH_policies;
    typedef typename GH_policies::Get_cost                                        GH_cost;
    typedef typename GH_policies::Get_placement                                   GH_placement;
    typedef SMS::Bounded_normal_change_placement<GH_placement>                    Bounded_GH_placement;
     

    bool check_mesh = CGAL::is_valid_polygon_mesh(inital_mesh);
    std::cout << "vaild or in valid" <<check_mesh<< std::endl;
    GH_policies gh_policies(inital_mesh);
    const GH_cost& gh_cost = gh_policies.get_cost();
    const GH_placement& gh_placement = gh_policies.get_placement();
    Bounded_GH_placement placement(gh_placement);

    std::cout << "Input mesh has " << num_vertices(inital_mesh) << " nv "<< num_edges(inital_mesh) << " ne "
        << num_faces(inital_mesh) << " nf" << std::endl;
    /*internal::cgal_enable_sms_trace = true;*/
    int r = SMS::edge_collapse(inital_mesh, stop,
        CGAL::parameters::get_cost(gh_cost)
        .get_placement(placement));
candice_chen
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  • Could you provide a minimal example showing your problem? The expected runtime should be a few seconds. Does it terminate? – sloriot Dec 06 '21 at 10:59
  • @sloriot , i update the my code and the runtime cost of two mesh. The project can teminate. I know the runtime should be few seconds,but i don't know why my project takes so long. – candice_chen Dec 07 '21 at 03:14
  • You did compile in release mode without assertions, right? Can you share the input that take a lot of time so that I can try to reproduce the issue? – sloriot Dec 07 '21 at 07:52
  • Thank you so much!! You remind me. I used the debug mode. The problem is solved. @sloriot – candice_chen Dec 08 '21 at 02:04

0 Answers0