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

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

Definition

Region type based on the quality of the least squares line fit applied to a segment set.

This class fits a line, using PCA, to chunks of 2D or 3D segments and controls the quality of this fit. If all quality conditions are satisfied, the chunk is accepted as a valid region, otherwise rejected.

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 Kernel::Segment_2 or Kernel::Segment_3

Is Model Of:

RegionType

Examples:

Shape_detection/region_growing_lines_on_segment_set.cpp.

Types
typedef GeomTraits::FT	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 > >
	Primitive type depends on the dimension of the input data.
using	Region_index_map = boost::associative_property_map< Region_unordered_map >

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

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

Constructor & Destructor Documentation

Least_squares_line_fit_region()

template<typename GeomTraits , typename Item_ , typename SegmentMap >

template<typename NamedParameters = parameters::Default_named_parameters>

CGAL::Shape_detection::Segment_set::Least_squares_line_fit_region< GeomTraits, Item_, SegmentMap >::Least_squares_line_fit_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

Template Parameters

InputRange

a model of ConstRange whose iterator type is RandomAccessIterator

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 an item from input_range to Kernel::Segment_2 or Kernel::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::Least_squares_line_fit_region< GeomTraits, Item_, SegmentMap >::is_part_of_region	(	const Item	query,
		const Region &
	)		const

implements RegionType::is_part_of_region().

This function controls 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

The last parameter is not used in this implementation.

Returns

Boolean true or false

is_valid_region()

template<typename GeomTraits , typename Item_ , typename SegmentMap >

bool CGAL::Shape_detection::Segment_set::Least_squares_line_fit_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.

Returns

Boolean true or false

primitive()

template<typename GeomTraits , typename Item_ , typename SegmentMap >

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

(

)

const

implements RegionType::primitive().

This function provides the last primitive that has been fitted with the region.

Returns

Primitive parameters that fits the region

Precondition

successful fitted primitive via successful call of update(region) with a sufficient large region

region_index_map()

template<typename GeomTraits , typename Item_ , typename SegmentMap >

Region_index_map CGAL::Shape_detection::Segment_set::Least_squares_line_fit_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::Least_squares_line_fit_region< GeomTraits, Item_, SegmentMap >::update

(

const Region &

region

)

implements RegionType::update().

This function fits the least squares line to all segments from the region.

Parameters

region

Segments of the region represented as Items.

Returns

Boolean true if the line fitting succeeded and false otherwise

Precondition

region.size() > 0