CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, PointMap, ConcurrencyTag, DiagonalizeTraits > Class Template Reference

#include <CGAL/Classification/Point_set_feature_generator.h>

Definition

template<typename GeomTraits, typename PointRange, typename PointMap, typename ConcurrencyTag, typename DiagonalizeTraits>
class CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, PointMap, ConcurrencyTag, DiagonalizeTraits >

generates a set of generic features for point set classification.

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

Warning

The generated features use data structures that are stored inside the generator. For this reason, the generator should be instantiated within the same scope as the feature set and should not be deleted before the feature set.

Template Parameters

GeomTraits	model of CGAL Kernel.
PointRange	model of ConstRange. Its iterator type is RandomAccessIterator and its value type is the key type of PointMap.
PointMap	model of ReadablePropertyMap whose key type is the value type of the iterator of PointRange and value type is GeomTraits::Point_3.
ConcurrencyTag	enables 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).
DiagonalizeTraits	model of DiagonalizeTraits used for matrix diagonalization. It can be omitted: if Eigen 3 (or greater) is available and CGAL_EIGEN3_ENABLED is defined: in that case, an overload using Eigen_diagonalize_traits is provided.

Public Types
using	Iso_cuboid_3 = typename GeomTraits::Iso_cuboid_3
using	Planimetric_grid = Classification::Planimetric_grid< GeomTraits, PointRange, PointMap >
using	Neighborhood = Classification::Point_set_neighborhood< GeomTraits, PointRange, PointMap >
using	Local_eigen_analysis = Classification::Local_eigen_analysis

Constructor
	Point_set_feature_generator (const PointRange &input, PointMap point_map, std::size_t nb_scales, float voxel_size=-1.f)
	initializes a feature generator from an input range.

Feature Generation
void	generate_point_based_features (Feature_set &features)
	generates geometric features based on point position information.
void	generate_eigen_features (Feature_set &features)
	generates geometric eigen features.
void	generate_dispersion_features (Feature_set &features)
	generates geometric features based on local dispersion information.
void	generate_elevation_features (Feature_set &features)
	generates geometric features based on elevation information.
void	generate_normal_based_features (Feature_set &features)
	generates geometric features based on normal analysis information.
template<typename VectorMap >
void	generate_normal_based_features (Feature_set &features, const VectorMap &normal_map)
	generates geometric features based on normal vector information.
template<typename ColorMap >
void	generate_color_based_features (Feature_set &features, const ColorMap &color_map)
	generates geometric features based on point color information.
template<typename EchoMap >
void	generate_echo_based_features (Feature_set &features, const EchoMap &echo_map)
	generates geometric features based on echo information.

Data Structures Access
const Iso_cuboid_3 &	bbox () const
	returns the bounding box of the input point set.
const Neighborhood &	neighborhood (std::size_t scale=0) const
	returns the neighborhood structure at scale scale.
const Planimetric_grid &	grid (std::size_t scale=0) const
	returns the planimetric grid structure at scale scale.
const Local_eigen_analysis &	eigen (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.
float	radius_neighbors (std::size_t scale=0) const
	returns the radius used for neighborhood queries at scale scale.
float	radius_dtm (std::size_t scale=0) const
	returns the radius used for digital terrain modeling at scale scale.

Constructor & Destructor Documentation

Point_set_feature_generator()

template<typename GeomTraits , typename PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, PointMap, ConcurrencyTag, DiagonalizeTraits >::Point_set_feature_generator	(	const PointRange &	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

input	point range.
point_map	property map to access the input points.
nb_scales	number of scales to compute.
voxel_size	smallest 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_color_based_features()

template<typename GeomTraits , typename PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

template<typename ColorMap >

void CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, PointMap, ConcurrencyTag, DiagonalizeTraits >::generate_color_based_features	(	Feature_set &	features,
		const ColorMap &	color_map
	)

generates geometric features based on point color information.

Generates CGAL::Classification::Feature::Color_channel with channels HUE, SATURATION and VALUE.

Template Parameters

ColorMap

model of ReadablePropertyMap whose key type is the value type of the iterator of PointRange and value type is CGAL::IO::Color.

Parameters

features	the feature set where the features are instantiated.
color_map	property map to access the colors of the input points (if any).

generate_dispersion_features()

template<typename GeomTraits , typename PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

void CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, PointMap, ConcurrencyTag, DiagonalizeTraits >::generate_dispersion_features

(

Feature_set &

features

)

generates geometric features based on local dispersion information.

At each scale, the following features are generated:

• CGAL::Classification::Feature::Distance_to_plane
• CGAL::Classification::Feature::Vertical_dispersion

Parameters

features

the feature set where the features are instantiated.

generate_echo_based_features()

template<typename GeomTraits , typename PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

template<typename EchoMap >

void CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, PointMap, ConcurrencyTag, DiagonalizeTraits >::generate_echo_based_features	(	Feature_set &	features,
		const EchoMap &	echo_map
	)

generates geometric features based on echo information.

At each scale, generates CGAL::Classification::Feature::Echo_scatter.

Template Parameters

EchoMap

model of ReadablePropertyMap whose key type is the value type of the iterator of PointRange and value type is std::size_t.

Parameters

features	the feature set where the features are instantiated.
echo_map	property map to access the echo values of the input points (if any).

generate_eigen_features()

template<typename GeomTraits , typename PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

void CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, PointMap, ConcurrencyTag, DiagonalizeTraits >::generate_eigen_features

(

Feature_set &

features

)

generates geometric eigen features.

At each scale, features CGAL::Classification::Feature::Eigenvalue with indices 0, 1 and 2 are generated.

Parameters

features

the feature set where the features are instantiated.

generate_elevation_features()

template<typename GeomTraits , typename PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

void CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, PointMap, ConcurrencyTag, DiagonalizeTraits >::generate_elevation_features

(

Feature_set &

features

)

generates geometric features based on elevation information.

At each scale, the following features are generated:

• CGAL::Classification::Feature::Elevation
• CGAL::Classification::Feature::Height_above
• CGAL::Classification::Feature::Height_below
• CGAL::Classification::Feature::Vertical_range

Parameters

features

the feature set where the features are instantiated.

generate_normal_based_features() [1/2]

template<typename GeomTraits , typename PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

void CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, PointMap, ConcurrencyTag, DiagonalizeTraits >::generate_normal_based_features

(

Feature_set &

features

)

generates geometric features based on normal analysis information.

At each scale, the version of CGAL::Classification::Feature::Verticality based on eigenvalue is generated.

Parameters

features

the feature set where the features are instantiated.

generate_normal_based_features() [2/2]

template<typename GeomTraits , typename PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

template<typename VectorMap >

void CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, PointMap, ConcurrencyTag, DiagonalizeTraits >::generate_normal_based_features	(	Feature_set &	features,
		const VectorMap &	normal_map
	)

generates geometric features based on normal vector information.

Generates the version of CGAL::Classification::Feature::Verticality based on normal vectors.

Template Parameters

VectorMap

model of ReadablePropertyMap whose key type is the value type of the iterator of PointRange and value type is GeomTraits::Vector_3.

Parameters

features	the feature set where the features are instantiated.
normal_map	property map to access the normal vectors of the input points (if any).

generate_point_based_features()

template<typename GeomTraits , typename PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

void CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, PointMap, ConcurrencyTag, DiagonalizeTraits >::generate_point_based_features

(

Feature_set &

features

)

generates geometric features based on point position information.

This is a meta-function that calls the following functions:

• generate_eigen_features()
• generate_dispersion_features()
• generate_elevation_features()
• The version of generate_normal_based_features() without a normal map

Parameters

features

the feature set where the features are instantiated.

grid_resolution()

template<typename GeomTraits , typename PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

float CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, 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 PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

float CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, 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 PointRange , typename PointMap , typename ConcurrencyTag , typename DiagonalizeTraits >

float CGAL::Classification::Point_set_feature_generator< GeomTraits, PointRange, 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).