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CGAL 4.13.1 - Classification
CGAL::Classification::Mesh_feature_generator< GeomTraits, FaceListGraph, PointMap, ConcurrencyTag, DiagonalizeTraits > Class Template Reference

#include <CGAL/Classification/Mesh_feature_generator.h>

Definition

template<typename GeomTraits, typename FaceListGraph, typename PointMap, typename ConcurrencyTag, typename DiagonalizeTraits = CGAL::Default_diagonalize_traits<float,3>>
class CGAL::Classification::Mesh_feature_generator< GeomTraits, FaceListGraph, PointMap, ConcurrencyTag, DiagonalizeTraits >

Generates a set of generic features for surface mesh classification.

This class takes care of computing all necessary data structures and of generating a set of generic features at multiple scales to increase the reliability of the classification.

A PointMap is required: this map should associate each face of the mesh to a representative point (for example, the center of mass of the face). It is used to generate point set features by considering the mesh as a point set.

Template Parameters
GeomTraitsmodel of CGAL Kernel.
FaceListGraphmodel of FaceListGraph.
PointMapmodel of ReadablePropertyMap whose key type is boost::graph_traits<FaceListGraph>::face_descriptor and value type is GeomTraits::Point_3.
ConcurrencyTagenables sequential versus parallel computation of CGAL::Classification::Local_eigen_analysis objects. Possible values are Parallel_tag (default value is CGAL is linked with TBB) or Sequential_tag (default value otherwise).
DiagonalizeTraitsmodel of DiagonalizeTraits used for matrix diagonalization. It can be omitted: if Eigen 3 (or greater) is available and CGAL_EIGEN3_ENABLED is defined then an overload using Eigen_diagonalize_traits is provided. Otherwise, the internal implementation Diagonalize_traits is used.

Public Types

typedef GeomTraits::Iso_cuboid_3 Iso_cuboid_3
 
typedef Classification::Planimetric_grid< GeomTraits, Face_range, PointMap > Planimetric_grid
 
typedef Classification::Mesh_neighborhood< FaceListGraphNeighborhood
 
typedef Classification::Local_eigen_analysis Local_eigen_analysis
 

Constructor

 Mesh_feature_generator (const FaceListGraph &input, PointMap point_map, std::size_t nb_scales, float voxel_size=-1.f)
 Initializes a feature generator from an input range. More...
 

Feature Generation

void generate_face_based_features (Feature_set &features)
 Generate geometric features based on face information. More...
 
void generate_point_based_features (Feature_set &features)
 Generate geometric features based on point position information. More...
 

Data Structures Access

const Iso_cuboid_3bbox () const
 Returns the bounding box of the input point set.
 
const Neighborhoodneighborhood (std::size_t scale=0) const
 Returns the neighborhood structure at scale scale.
 
const Planimetric_gridgrid (std::size_t scale=0) const
 Returns the planimetric grid structure at scale scale.
 
const Local_eigen_analysiseigen (std::size_t scale=0) const
 Returns the local eigen analysis structure at scale scale.
 

Parameters

std::size_t number_of_scales () const
 Returns the number of scales that were computed.
 
float grid_resolution (std::size_t scale=0) const
 Returns the grid resolution at scale scale. More...
 
float radius_neighbors (std::size_t scale=0) const
 Returns the radius used for neighborhood queries at scale scale. More...
 
float radius_dtm (std::size_t scale=0) const
 Returns the radius used for digital terrain modeling at scale scale. More...
 

Constructor & Destructor Documentation

◆ Mesh_feature_generator()

template<typename GeomTraits , typename FaceListGraph , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits = CGAL::Default_diagonalize_traits<float,3>>
CGAL::Classification::Mesh_feature_generator< GeomTraits, FaceListGraph, PointMap, ConcurrencyTag, DiagonalizeTraits >::Mesh_feature_generator ( const FaceListGraph input,
PointMap  point_map,
std::size_t  nb_scales,
float  voxel_size = -1.f 
)

Initializes a feature generator from an input range.

If not provided by the user, The size of the smallest scale is automatically estimated using a method equivalent to CGAL::compute_average_spacing() using 6 neighbors. The data structures needed (Neighborhood, Planimetric_grid and Local_eigen_analysis) are computed at nb_scales recursively larger scales.

Parameters
inputinput mesh.
point_mapproperty map to access a representative point of each face.
nb_scalesnumber of scales to compute.
voxel_sizesmallest scale used as a voxel size for the planimetric grid (if the default value -1 is used, its value is automatically estimated).

Member Function Documentation

◆ generate_face_based_features()

template<typename GeomTraits , typename FaceListGraph , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits = CGAL::Default_diagonalize_traits<float,3>>
void CGAL::Classification::Mesh_feature_generator< GeomTraits, FaceListGraph, PointMap, ConcurrencyTag, DiagonalizeTraits >::generate_face_based_features ( Feature_set features)

Generate geometric features based on face information.

At each scale, the following features are generated:

Parameters
featuresthe feature set where the features are instantiated.

◆ generate_point_based_features()

template<typename GeomTraits , typename FaceListGraph , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits = CGAL::Default_diagonalize_traits<float,3>>
void CGAL::Classification::Mesh_feature_generator< GeomTraits, FaceListGraph, PointMap, ConcurrencyTag, DiagonalizeTraits >::generate_point_based_features ( Feature_set features)

Generate geometric features based on point position information.

At each scale, the following features are generated by considering the mesh as a point cloud through PointMap:

Parameters
featuresthe feature set where the features are instantiated.

◆ grid_resolution()

template<typename GeomTraits , typename FaceListGraph , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits = CGAL::Default_diagonalize_traits<float,3>>
float CGAL::Classification::Mesh_feature_generator< GeomTraits, FaceListGraph, PointMap, ConcurrencyTag, DiagonalizeTraits >::grid_resolution ( std::size_t  scale = 0) const

Returns the grid resolution at scale scale.

This resolution is the length and width of a cell of the Planimetric_grid defined at this scale.

◆ radius_dtm()

template<typename GeomTraits , typename FaceListGraph , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits = CGAL::Default_diagonalize_traits<float,3>>
float CGAL::Classification::Mesh_feature_generator< GeomTraits, FaceListGraph, PointMap, ConcurrencyTag, DiagonalizeTraits >::radius_dtm ( std::size_t  scale = 0) const

Returns the radius used for digital terrain modeling at scale scale.

This radius represents the minimum size of a building at this scale.

◆ radius_neighbors()

template<typename GeomTraits , typename FaceListGraph , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits = CGAL::Default_diagonalize_traits<float,3>>
float CGAL::Classification::Mesh_feature_generator< GeomTraits, FaceListGraph, PointMap, ConcurrencyTag, DiagonalizeTraits >::radius_neighbors ( std::size_t  scale = 0) const

Returns the radius used for neighborhood queries at scale scale.

This radius is the smallest radius that is relevant from a geometric point of view at this scale (that is to say that encloses a few cells of Planimetric_grid).