CGAL users discussion list

[Jack Lee <>]

Hello,

I am trying to generate a 3D mesh from multi-labelled images, with 
polylines to preserve the corners.

Currently I'm trying it with a synthetically generated image, which is a 
cylinder with a step increase in the diameter along its length. I've 
tried the code below, which builds and executes without problem, but it 
doesn't preserve the lines at all (see the screenshot). It's probably 
(hopefully) some simple mistake, but I can't seem to find it. Could 
somebody help please?

I will attach the image stack if someone is interested, but for now, the 
code looks like:

-----------------------------

// Domain
typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Labeled_image_mesh_domain_3<CGAL::Image_3,K> Mesh_domainImage;
typedef CGAL::Mesh_domain_with_polyline_features_3<Mesh_domainImage> 
Mesh_domain;

-----------------------------

  // sizing field
  Sizing_field   size(4.5);
  size.set_size((double) 2.0, 3, (double) 128.0);

  C3t3 c3t3;
  Mesh_criteria criteria(facet_angle=30, facet_size=4.5, facet_distance=5,
                         cell_radius_edge_ratio=2, cell_size=size);

  std::cout << "reading " << image_src << "..." << std::endl;
  CGAL::Image_3 image;
  image.read(image_src.c_str());
  Mesh_domain domain(image);

  // Create the edges to preserve
  Polylines polylines (1);
  Polyline_3& polyline = polylines.front();
  for(int i = 0; i < 360; ++i)
  {
    Point p (std::cos(i*CGAL_PI/180)*25+49, 
std::sin(i*CGAL_PI/180)*25+49, 49);
    polyline.push_back(p);
  }
  polyline.push_back(polyline.front()); // close the line
  // Insert edge in domain
  domain.add_features(polylines.begin(), polylines.end());

  std::cout << "generating mesh ..." << std::endl;
  c3t3 = CGAL::make_mesh_3<C3t3>(domain, criteria,
                                 odt(time_limit=g_time/2),
                                 lloyd(time_limit=g_time/2),
                                 perturb(sliver_bound=20, 
time_limit=l_time/2),
                                 exude(time_limit=l_time/2));

Attachment: md.png
Description: PNG image