CGAL 6.2 - Shape Detection

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Shape_detection/efficient_RANSAC_with_point_access.cpp
#include <fstream>
#include <iostream>
#include <CGAL/Timer.h>
#include <CGAL/number_utils.h>
#include <CGAL/property_map.h>
#include <CGAL/IO/read_points.h>
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Shape_detection/Efficient_RANSAC.h>
// Type declarations.
typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef Kernel::FT FT;
typedef std::pair<Kernel::Point_3, Kernel::Vector_3> Point_with_normal;
typedef std::vector<Point_with_normal> Pwn_vector;
typedef CGAL::First_of_pair_property_map<Point_with_normal> Point_map;
typedef CGAL::Second_of_pair_property_map<Point_with_normal> Normal_map;
typedef CGAL::Shape_detection::Efficient_RANSAC_traits
<Kernel, Pwn_vector, Point_map, Normal_map> Traits;
typedef CGAL::Shape_detection::Efficient_RANSAC<Traits> Efficient_ransac;
typedef CGAL::Shape_detection::Plane<Traits> Plane;
int main(int argc, char** argv) {
// Points with normals.
Pwn_vector points;
// Load point set from a file.
if (!CGAL::IO::read_points(
((argc > 1) ? argv[1] : CGAL::data_file_path("points_3/cube.pwn")),
std::back_inserter(points),
CGAL::parameters::point_map(Point_map()).
normal_map(Normal_map()))) {
std::cerr << "Error: cannot read file cube.pwn!" << std::endl;
return EXIT_FAILURE;
}
// Instantiate shape detection engine.
Efficient_ransac ransac;
// Provide input data.
ransac.set_input(points);
// Register detection of planes.
ransac.add_shape_factory<Plane>();
// Measure time before setting up the shape detection.
CGAL::Timer time;
time.start();
// Build internal data structures.
ransac.preprocess();
// Measure time after preprocessing.
time.stop();
std::cout << "preprocessing took: " << time.time() * 1000 << "ms" << std::endl;
// Perform detection several times and choose result with the highest coverage.
Efficient_ransac::Shape_range shapes = ransac.shapes();
FT best_coverage = 0;
for (std::size_t i = 0; i < 3; ++i) {
// Reset timer.
time.reset();
time.start();
// Detect shapes.
ransac.detect();
// Measure time after detection.
time.stop();
// Compute coverage, i.e. ratio of the points assigned to a shape.
FT coverage =
FT(points.size() - ransac.number_of_unassigned_points()) / FT(points.size());
// Print number of assigned shapes and unassigned points.
std::cout << "time: " << time.time() * 1000 << "ms" << std::endl;
std::cout << ransac.shapes().end() - ransac.shapes().begin()
<< " primitives, " << coverage << " coverage" << std::endl;
// Choose result with the highest coverage.
if (coverage > best_coverage) {
best_coverage = coverage;
// Efficient_ransac::shapes() provides
// an iterator range to the detected shapes.
shapes = ransac.shapes();
}
}
Efficient_ransac::Shape_range::iterator it = shapes.begin();
while (it != shapes.end()) {
std::shared_ptr<Efficient_ransac::Shape> shape = *it;
// Use Shape_base::info() to print the parameters of the detected shape.
std::cout << (*it)->info();
// Sums distances of points to the detected shapes.
FT sum_distances = 0;
// Iterate through point indices assigned to each detected shape.
std::vector<std::size_t>::const_iterator
index_it = (*it)->indices_of_assigned_points().begin();
while (index_it != (*it)->indices_of_assigned_points().end()) {
// Retrieve point.
const Point_with_normal& p = *(points.begin() + (*index_it));
// Adds Euclidean distance between point and shape.
sum_distances += CGAL::sqrt((*it)->squared_distance(p.first));
// Proceed with the next point.
index_it++;
}
// Compute and print the average distance.
FT average_distance = sum_distances / shape->indices_of_assigned_points().size();
std::cout << " average distance: " << average_distance << std::endl;
// Proceed with the next detected shape.
it++;
}
return EXIT_SUCCESS;
}
Efficient_RANSAC.h
A convenience header that includes all classes related to the efficient RANSAC algorithm.
CGAL::Exact_predicates_inexact_constructions_kernel
CGAL::Shape_detection::Efficient_RANSAC
Shape detection algorithm based on the RANSAC method.
Definition: Efficient_RANSAC.h:60
CGAL::Shape_detection::Plane
Plane implements Shape_base.
Definition: Plane.h:33
CGAL::IO::read_points
bool read_points(const std::string &fname, PointOutputIterator output, const NamedParameters &np=parameters::default_values())
CGAL::sqrt
NT sqrt(const NT &x)
Kernel
CGAL::First_of_pair_property_map
CGAL::Second_of_pair_property_map
CGAL::Shape_detection::Efficient_RANSAC_traits
Default traits class for the CGAL::Shape_detection::Efficient_RANSAC.
Definition: Efficient_RANSAC_traits.h:41