CGAL users discussion list

[williamlai3a <>]

Hi All,

I am a newbie to CGAL, I am trying code from CGAL github master build
(v4.12) to do 3D point set processing.
I am using the following:
typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef Kernel::FT FT;
typedef Kernel::Point_3 Point;
typedef Kernel::Vector_3 Vector;
typedef CGAL::Point_set_3<Point> Point_set;

However, in my original .xyz point cloud, I am having high precision like:
841293.765978 818818.600281 90.933151
841293.765000 818818.599880 90.906294
841293.764292 818818.599046 90.960005
841284.839693 818813.763807 90.725665
841284.822854 818813.767425 90.684145
841284.822320 818813.766970 90.696840
841284.821787 818813.766515 90.709534
841284.825319 818813.768227 90.721745

After processing normal, and I write back the points to a .xyz, the point
precision becomes:
841294 818819 90.9332 0 0 0
841294 818819 90.9063 0 0 0
841294 818819 90.96 0 0 0
841285 818814 90.7257 0 0 0
841285 818814 90.6841 0 0 0
841285 818814 90.6968 0 0 0
841285 818814 90.7095 0 0 0
841285 818814 90.7217 0 0 0

Problem 1:
Seems to me that the output is being trimmed to 6 significant figure.
Are there any ways to output much higher significant figure, say 12?

Problem 2:
In my normal reconstruction processing, I am trying to use the following:
// Computes average spacing.
    const unsigned int nb_neighbors = 6; // 1 ring
    FT average_spacing = CGAL::compute_average_spacing<Concurrency_tag>(
                            point_sets,  // CGAL::Point_set_3<Point>
                            nb_neighbors,
                           
CGAL::parameters::point_map(point_sets.point_map())
                        );

        point_sets.add_normal_map();
        CGAL::vcm_estimate_normals(
            point_sets,
            CGAL::to_double(average_spacing)*20,
            CGAL::to_double(average_spacing),
            CGAL::parameters::point_map(point_sets.point_map()).
                              normal_map(point_sets.normal_map())
        );

        Point_set::iterator unoriented_points_begin =
        CGAL::mst_orient_normals(point_sets,
                                 nb_neighbors,
                                
CGAL::parameters::point_map(point_sets.point_map()).
                                                  
normal_map(point_sets.normal_map())
        );
        // Optional: delete points with an unoriented normal
        // if you plan to call a reconstruction algorithm that expects
oriented normals.
        point_sets.remove(unoriented_points_begin, point_sets.end());
        point_sets.collect_garbage();

As you can see from the above output, all normals are <0 0 0>
However, my point cloud contains a lot of planar surfaces with different
orientation.
Are there any things wrong with my code? Parameter problem? or I am doing in
a wrong concept way.

Thank you very much in advance for any suggestions and recommendation.

Best regards,
William 



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