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[cgal-discuss] Why does number of segments==number of faces ?


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  • From: Iasonm <>
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  • Subject: [cgal-discuss] Why does number of segments==number of faces ?
  • Date: Thu, 27 Apr 2017 08:39:43 -0700 (PDT)
  • Authentication-results: mail2-smtp-roc.national.inria.fr; spf=None ; spf=SoftFail ; spf=None
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Hello ,

I am trying to segment a mesh using the following code:

void segmentMesh(){
typedef boost::graph_traits<CGALSurfaceMesh>::face_descriptor
face_descriptor;
typedef CGALSurfaceMesh::Property_map<face_descriptor,double>
Facet_double_map;
Facet_double_map sdf_property_map;


sdf_property_map=M.add_property_map<face_descriptor,double>("f:sdf").first;

// compute SDF values
// We can't use default parameters for number of rays, and cone
angle
// and the postprocessing
CGAL::sdf_values(M, sdf_property_map, 2.0 / 3.0 * CGAL_PI, 25,
true);
// create a property-map for segment-ids
typedef CGALSurfaceMesh::Property_map<face_descriptor, std::size_t>
Facet_int_map;
Facet_int_map segment_property_map
=M.add_property_map<face_descriptor,std::size_t>("f:sid").first;;

// segment the mesh using default parameters for number of levels,
and smoothing lambda
// Any other scalar values can be used instead of using SDF values
computed using the CGAL function
std::size_t number_of_segments =
CGAL::segmentation_from_sdf_values(M, sdf_property_map,
segment_property_map);

std::cout << "Number of segments: " << number_of_segments <<
std::endl;
}
Everytime number_of_segments equals number of faces. This does not change
when I load another .obj ,
The sdf values seem ok:
sdf_property_map
[0] 0.8370299962032144 double
[1] 0.8302092195108647 double
[2] 0 double
[3] 0 double
[4] 0.8409042568287671 double
[5] 0.8408585619378204 double
[6] 0 double
[7] 0 double
[8] 0.7682886461557734 double
[9] 1 double
[10] 0 double
[11] 0 double
[12] 0.6922190247566234 double
[13] 0.6946973322833983 double
[14] 0.7329067924334197 double
[15] 0.7766550861844591 double
[16] 0.6946973322833983 double
[17] 0.6922190247566236 double
[18] 0.7766550861844591 double
[19] 0.7329067924334197 double
[20] 0.7223775647174728 double
[21] 0.7132597505108464 double
[22] 0 double
[23] 0.7544947132430431 double
[24] 0.7187772404286814 double
[25] 0.7518370088577582 double
[26] 0.651523966538904 double
[27] 0.6388096368864299 double
[28] 0.7320518183718274 double
[29] 0.7274001899698522 double
[30] 0.642578387110068 double
[31] 0.6491369547477115 double
[32] 0 double
[33] 0 double
[34] 0.4715324806384383 double
[35] 0.4709893975524506 double
[36] 0.7046211151331574 double
[37] 0.6863547051607206 double
[38] 0.503769122276115 double
[39] 0.5220265562441847 double
[40] 0.6863547051607206 double
[41] 0.7046211151331574 double
[42] 0 double
[43] 0 double
[44] 0.439175491328876 double
[45] 0.4547852145305106 double
[46] 0.4674809609375916 double
[47] 0.4319148395824393 double
[48] 0.7816054032559208 double
[49] 0.7481725761853011 double
[50] 5.466811527473978e-17 double
[51] 5.564433161893157e-17 double
[52] 0.7481725761853011 double
[53] 0.7816054032559208 double
[54] 0.531941346270403 double
[55] 0.5176809398969037 double
[56] 0.5631417370150187 double
[57] 0.3711396563719775 double
[58] 0.5792711145774221 double
[59] 0.393846048669109 double
[60] 0.280795207809901 double
[61] 0.2755911468606309 double
[62] 0.2808547577076206 double
[63] 0.2756548453890119 double
[64] 0.275591146860631 double
[65] 0.280795207809901 double
[66] 0.2756548453890119 double
[67] 0.2808547577076206 double
[68] 0 double
[69] 0 double
[70] 0 double
[71] 0 double
[72] 0.6744300542068228 double
[73] 0.6580958382600026 double
[74] 0.3423945508066144 double
[75] 0.4668586784283277 double
[76] 0.7919433486621358 double
[77] 0.7733719654580617 double
[78] 0.4563102973815411 double
[79] 0.2796173080630547 double
[80] 0 double
[81] 0 double
[82] 0 double
[83] 0 double
[84] 0.7720729114423587 double
[85] 0.7964883503765292 double
[86] 0.6479947042483273 double
[87] 0.6553937510618364 double
[88] 0.7904543847051128 double
[89] 0.7919075146603214 double
[90] 0.6570894870135487 double
[91] 0.6506725916476378 double
[92] 0 double
[93] 0 double
[94] 0.4937888701326119 double
[95] 0.486533941862835 double

Since I successfully ran the cactus example,
I suspect there is something wrong with how I build M (the surface mesh).
I build the surface mesh using the following code:

void buildPolygonMesh() {
M.clear();
std::cout << "Building CGALPolygonMesh.." << std::endl;
std::vector<Kernel::Point_3> points;
std::vector<std::vector&lt;std::size_t>> polygons;

for (auto const &vert : vertices) {
points.push_back(
Kernel::Point_3((vert.Position.x - centerOfMass.x) /
maxDim,
(vert.Position.y - centerOfMass.y) /
maxDim,
(vert.Position.z - centerOfMass.z) /
maxDim));
}
for (size_t i = 0; i < indices.size(); i += 3) {
std::vector<std::size_t> tri{indices[i], indices[i + 1],
indices[i + 2]};
polygons.push_back(tri);
}
std::cout << "is polygon soup polygon mesh:"
<<
CGAL::Polygon_mesh_processing::is_polygon_soup_a_polygon_mesh(
polygons)
<< std::endl;
CGAL::Polygon_mesh_processing::polygon_soup_to_polygon_mesh(points,

polygons, M);
std::cout << "Finished building Polygon Mesh." << std::endl;
}

Any ideas?



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