CGAL 5.3.1 - Classification
Classification/example_classification.cpp
#if defined (_MSC_VER) && !defined (_WIN64)
#pragma warning(disable:4244) // boost::number_distance::distance()
// converts 64 to 32 bits integers
#endif
#include <CGAL/Simple_cartesian.h>
#include <CGAL/Classification.h>
#include <CGAL/bounding_box.h>
#include <CGAL/tags.h>
#include <CGAL/IO/read_points.h>
#include <CGAL/IO/write_ply_points.h>
#include <CGAL/Real_timer.h>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <string>
typedef CGAL::Parallel_if_available_tag Concurrency_tag;
typedef Kernel::Point_3 Point;
typedef Kernel::Iso_cuboid_3 Iso_cuboid_3;
typedef std::vector<Point> Point_range;
typedef CGAL::Identity_property_map<Point> Pmap;
namespace Classification = CGAL::Classification;
typedef Classification::Sum_of_weighted_features_classifier Classifier;
typedef Classification::Planimetric_grid<Kernel, Point_range, Pmap> Planimetric_grid;
typedef Classification::Point_set_neighborhood<Kernel, Point_range, Pmap> Neighborhood;
typedef Classification::Local_eigen_analysis Local_eigen_analysis;
typedef Classification::Label_handle Label_handle;
typedef Classification::Feature_handle Feature_handle;
typedef Classification::Label_set Label_set;
typedef Classification::Feature_set Feature_set;
typedef Classification::Feature::Distance_to_plane<Point_range, Pmap> Distance_to_plane;
typedef Classification::Feature::Elevation<Kernel, Point_range, Pmap> Elevation;
typedef Classification::Feature::Vertical_dispersion<Kernel, Point_range, Pmap> Dispersion;
int main (int argc, char** argv)
{
const char* filename = (argc > 1) ? argv[1] : "data/b9.ply";
std::cerr << "Reading input" << std::endl;
std::vector<Point> pts;
if (!(CGAL::IO::read_points(filename, std::back_inserter(pts),
// the PLY reader expects a binary file by default
CGAL::parameters::use_binary_mode(false))))
{
std::cerr << "Error: cannot read " << filename << std::endl;
return EXIT_FAILURE;
}
float grid_resolution = 0.34f;
unsigned int number_of_neighbors = 6;
std::cerr << "Computing useful structures" << std::endl;
Iso_cuboid_3 bbox = CGAL::bounding_box (pts.begin(), pts.end());
Planimetric_grid grid (pts, Pmap(), bbox, grid_resolution);
Neighborhood neighborhood (pts, Pmap());
Local_eigen_analysis eigen
= Local_eigen_analysis::create_from_point_set
(pts, Pmap(), neighborhood.k_neighbor_query(number_of_neighbors));
float radius_neighbors = 1.7f;
float radius_dtm = 15.0f;
std::cerr << "Computing features" << std::endl;
Feature_set features;
features.begin_parallel_additions(); // No effect in sequential mode
Feature_handle distance_to_plane = features.add<Distance_to_plane> (pts, Pmap(), eigen);
Feature_handle dispersion = features.add<Dispersion> (pts, Pmap(), grid,
radius_neighbors);
Feature_handle elevation = features.add<Elevation> (pts, Pmap(), grid,
radius_dtm);
features.end_parallel_additions(); // No effect in sequential mode
Label_set labels;
// Init name only
Label_handle ground = labels.add ("ground");
// Init name and color
Label_handle vegetation = labels.add ("vegetation", CGAL::IO::Color(0,255,0));
// Init name, Color and standard index (here, ASPRS building index)
Label_handle roof = labels.add ("roof", CGAL::IO::Color (255, 0, 0), 6);
std::cerr << "Setting weights" << std::endl;
Classifier classifier (labels, features);
classifier.set_weight (distance_to_plane, 6.75e-2f);
classifier.set_weight (dispersion, 5.45e-1f);
classifier.set_weight (elevation, 1.47e1f);
std::cerr << "Setting effects" << std::endl;
classifier.set_effect (ground, distance_to_plane, Classifier::NEUTRAL);
classifier.set_effect (ground, dispersion, Classifier::NEUTRAL);
classifier.set_effect (ground, elevation, Classifier::PENALIZING);
classifier.set_effect (vegetation, distance_to_plane, Classifier::FAVORING);
classifier.set_effect (vegetation, dispersion, Classifier::FAVORING);
classifier.set_effect (vegetation, elevation, Classifier::NEUTRAL);
classifier.set_effect (roof, distance_to_plane, Classifier::NEUTRAL);
classifier.set_effect (roof, dispersion, Classifier::NEUTRAL);
classifier.set_effect (roof, elevation, Classifier::FAVORING);
// Run classification
std::cerr << "Classifying" << std::endl;
std::vector<int> label_indices (pts.size(), -1);
CGAL::Real_timer t;
t.start();
Classification::classify<CGAL::Parallel_if_available_tag> (pts, labels, classifier, label_indices);
t.stop();
std::cerr << "Raw classification performed in " << t.time() << " second(s)" << std::endl;
t.reset();
t.start();
Classification::classify_with_local_smoothing<CGAL::Parallel_if_available_tag>
(pts, Pmap(), labels, classifier,
neighborhood.sphere_neighbor_query(radius_neighbors),
label_indices);
t.stop();
std::cerr << "Classification with local smoothing performed in " << t.time() << " second(s)" << std::endl;
t.reset();
t.start();
Classification::classify_with_graphcut<CGAL::Parallel_if_available_tag>
(pts, Pmap(), labels, classifier,
neighborhood.k_neighbor_query(12),
0.2f, 4, label_indices);
t.stop();
std::cerr << "Classification with graphcut performed in " << t.time() << " second(s)" << std::endl;
// Save the output in a colored PLY format
std::vector<unsigned char> red, green, blue;
red.reserve(pts.size());
green.reserve(pts.size());
blue.reserve(pts.size());
for (std::size_t i = 0; i < pts.size(); ++ i)
{
Label_handle label = labels[std::size_t(label_indices[i])];
unsigned r = 0, g = 0, b = 0;
if (label == ground)
{
r = 245; g = 180; b = 0;
}
else if (label == vegetation)
{
r = 0; g = 255; b = 27;
}
else if (label == roof)
{
r = 255; g = 0; b = 170;
}
red.push_back(r);
green.push_back(g);
blue.push_back(b);
}
std::ofstream f ("classification.ply");
(f, CGAL::make_range (boost::counting_iterator<std::size_t>(0),
boost::counting_iterator<std::size_t>(pts.size())),
CGAL::make_ply_point_writer (CGAL::make_property_map(pts)),
std::make_pair(CGAL::make_property_map(red), CGAL::PLY_property<unsigned char>("red")),
std::make_pair(CGAL::make_property_map(green), CGAL::PLY_property<unsigned char>("green")),
std::make_pair(CGAL::make_property_map(blue), CGAL::PLY_property<unsigned char>("blue")));
std::cerr << "All done" << std::endl;
return EXIT_SUCCESS;
}