CGAL::Shape_detection::Segment_set::Line_segment_region< GeomTraits, Item_, SegmentMap > Class Template Reference

#include <CGAL/Shape_detection/Region_growing/Segment_set/Line_segment_region.h>

Definition

template<typename GeomTraits, typename Item_, typename SegmentMap>
class CGAL::Shape_detection::Segment_set::Line_segment_region< GeomTraits, Item_, SegmentMap >

Region type based on the line of the first segment selected.

This class uses the supporting line of the first segment picked for the region and expands it for all segments with a direction close to that of the first segment (close being defined by the maximum_distance parameter) and such that endpoints are not far from that supporting line (far being defined by the maximum_angle or cosine_of_maximum_angle parameter).

Template Parameters

GeomTraits	a model of Kernel
Item_	a descriptor representing a given segment. Must be a model of Hashable.
SegmentMap	a model of ReadablePropertyMap whose key type is Item_ and value type is GeomTraits::Segment_2 or GeomTraits::Segment_3

Is model of

RegionType

Examples

Shape_detection/region_growing_lines_on_segment_set.cpp.

Types
using	Segment_map = SegmentMap
using	Segment_type = typename Segment_map::value_type
using	FT = typename GeomTraits::FT
	Number type.
using	Item = Item_
	Item type.
using	Region = std::vector< Item >
using	Primitive = typename GeomTraits::Line_2 or typename GeomTraits::Line_3
using	Region_unordered_map = std::unordered_map< Item, std::size_t, internal::hash_item< Item > >
using	Region_index_map = boost::associative_property_map< Region_unordered_map >

Initialization
template<typename NamedParameters = parameters::Default_named_parameters>
	Line_segment_region (const NamedParameters &np=parameters::default_values())
	initializes all internal data structures.

Access
Region_index_map	region_index_map ()
	implements RegionType::region_index_map().
Primitive	primitive () const
	implements RegionType::primitive().
bool	is_part_of_region (const Item query, const Region &) const
	implements RegionType::is_part_of_region().
bool	is_valid_region (const Region &region) const
	implements RegionType::is_valid_region().
bool	update (const Region &region)
	implements RegionType::update().

Constructor & Destructor Documentation

Line_segment_region()

template<typename GeomTraits , typename Item_ , typename SegmentMap >

template<typename NamedParameters = parameters::Default_named_parameters>

CGAL::Shape_detection::Segment_set::Line_segment_region< GeomTraits, Item_, SegmentMap >::Line_segment_region

(

const NamedParameters &

np = parameters::default_values()

)

initializes all internal data structures.

Template Parameters

NamedParameters

a sequence of Named Parameters

Parameters

np	a sequence of Named Parameters among the ones listed below

Optional Named Parameters

maximum_distance the maximum distance from the furthest vertex of a segment to a line Type: GeomTraits::FT Default: 1
maximum_angle the maximum angle in degrees between the direction of a segment and the direction of a line Type: GeomTraits::FT Default: 25 degrees
cosine_of_maximum_angle the cosine value cos(maximum_angle * PI / 180), to be used instead of the parameter maximum_angle() Type: GeomTraits::FT Default: cos(25 * PI / 180)
minimum_region_size the minimum number of segments a region must have Type: std::size_t Default: 1
segment_map an instance of SegmentMap that maps Item_ to GeomTraits::Segment_2 or GeomTraits::Segment_3 Default: SegmentMap()
geom_traits an instance of GeomTraits Default: GeomTraits()

Precondition

maximum_distance >= 0

maximum_angle >= 0 && maximum_angle <= 90

cosine_of_maximum_angle >= 0 && cosine_of_maximum_angle <= 1

minimum_region_size > 0

Member Function Documentation

is_part_of_region()

template<typename GeomTraits , typename Item_ , typename SegmentMap >

bool CGAL::Shape_detection::Segment_set::Line_segment_region< GeomTraits, Item_, SegmentMap >::is_part_of_region	(	const Item	query,
		const Region &
	)		const

implements RegionType::is_part_of_region().

This function determines if a segment with the index query is within the maximum_distance from the corresponding line and if the angle between the direction of this segment and the line's direction is within the maximum_angle. If both conditions are satisfied, it returns true, otherwise false.

Parameters

query

item of the query segment

is_valid_region()

template<typename GeomTraits , typename Item_ , typename SegmentMap >

bool CGAL::Shape_detection::Segment_set::Line_segment_region< GeomTraits, Item_, SegmentMap >::is_valid_region

(

const Region &

region

)

const

implements RegionType::is_valid_region().

This function controls if the region contains at least minimum_region_size segments.

Parameters

region

Segments of the region represented as Items.

primitive()

template<typename GeomTraits , typename Item_ , typename SegmentMap >

Primitive CGAL::Shape_detection::Segment_set::Line_segment_region< GeomTraits, Item_, SegmentMap >::primitive

(

)

const

implements RegionType::primitive().

This function provides the support line of the seed segment.

Returns

Primitive parameters that fits the region

Precondition

is_valid_region(region)

update(region)

region_index_map()

template<typename GeomTraits , typename Item_ , typename SegmentMap >

Region_index_map CGAL::Shape_detection::Segment_set::Line_segment_region< GeomTraits, Item_, SegmentMap >::region_index_map

(

)

implements RegionType::region_index_map().

This function creates an empty property map that maps iterators on the input range Item to std::size_t.

update()

template<typename GeomTraits , typename Item_ , typename SegmentMap >

bool CGAL::Shape_detection::Segment_set::Line_segment_region< GeomTraits, Item_, SegmentMap >::update

(

const Region &

region

)

implements RegionType::update().

This function uses the support line of the seed segment as primitive.

Parameters

region

Segments of the region represented as Items.

Returns

Boolean true if the line fitting succeeded and false otherwise

Precondition

region.size() > 0