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

Definition

Region type based on the quality of the least squares line fit applied to 2D points.

This class fits a line, using PCA, to chunks of points in a 2D point set 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	must be a model of `Kernel`.
InputRange	must be a model of `ConstRange` whose iterator type is `RandomAccessIterator`.
PointMap	must be an `LvaluePropertyMap` whose key type is the value type of the input range and value type is `Kernel::Point_2`.
NormalMap	must be an `LvaluePropertyMap` whose key type is the value type of the input range and value type is `Kernel::Vector_2`.

Is Model Of:: RegionType

Examples:: Shape_detection/region_growing_lines_on_point_set_2.cpp.

Types
typedef GeomTraits::FT	FT
	Number type.

Initialization
	Least_squares_line_fit_region (const InputRange &input_range, const FT distance_threshold=FT(1), const FT angle_threshold=FT(25), const std::size_t min_region_size=2, const PointMap point_map=PointMap(), const NormalMap normal_map=NormalMap(), const GeomTraits traits=GeomTraits())
	initializes all internal data structures. More...

Access
bool	is_part_of_region (const std::size_t, const std::size_t query_index, const std::vector< std::size_t > &) const
	implements `RegionType::is_part_of_region()`. More...

bool	is_valid_region (const std::vector< std::size_t > &region) const
	implements `RegionType::is_valid_region()`. More...

void	update (const std::vector< std::size_t > &region)
	implements `RegionType::update()`. More...

Constructor & Destructor Documentation

◆ Least_squares_line_fit_region()

template<typename GeomTraits , typename InputRange , typename PointMap , typename NormalMap >

CGAL::Shape_detection::Point_set::Least_squares_line_fit_region< GeomTraits, InputRange, PointMap, NormalMap >::Least_squares_line_fit_region	(	const InputRange &	input_range,
		const FT	distance_threshold = `FT(1)`,
		const FT	angle_threshold = `FT(25)`,
		const std::size_t	min_region_size = `2`,
		const PointMap	point_map = `PointMap()`,
		const NormalMap	normal_map = `NormalMap()`,
		const GeomTraits	traits = `GeomTraits()`
	)

initializes all internal data structures.

Parameters

input_range	an instance of `InputRange` with 2D points and corresponding 2D normal vectors
distance_threshold	the maximum distance from a point to a line. Default is 1.
angle_threshold	the maximum accepted angle in degrees between the normal of a point and the normal of a line. Default is 25 degrees.
min_region_size	the minimum number of 2D points a region must have. Default is 2.
point_map	an instance of `PointMap` that maps an item from `input_range` to `Kernel::Point_2`
normal_map	an instance of `NormalMap` that maps an item from `input_range` to `Kernel::Vector_2`
traits	an instance of `GeomTraits`

Precondition: input_range.size() > 0; distance_threshold >= 0; angle_threshold >= 0 && angle_threshold <= 90; min_region_size > 0

Member Function Documentation

◆ is_part_of_region()

template<typename GeomTraits , typename InputRange , typename PointMap , typename NormalMap >

bool CGAL::Shape_detection::Point_set::Least_squares_line_fit_region< GeomTraits, InputRange, PointMap, NormalMap >::is_part_of_region	(	const std::size_t	,
		const std::size_t	query_index,
		const std::vector< std::size_t > &
	)		const

implements RegionType::is_part_of_region().

This function controls if a point with the index query_index is within the distance_threshold from the corresponding line and if the angle between its normal and the line's normal is within the angle_threshold. If both conditions are satisfied, it returns true, otherwise false.

Parameters

query_index index of the query point

The first and third parameters are not used in this implementation.

Returns: Boolean true or false

Precondition: query_index >= 0 && query_index < input_range.size()

◆ is_valid_region()

template<typename GeomTraits , typename InputRange , typename PointMap , typename NormalMap >

bool CGAL::Shape_detection::Point_set::Least_squares_line_fit_region< GeomTraits, InputRange, PointMap, NormalMap >::is_valid_region ( const std::vector< std::size_t > & region ) const

implements RegionType::is_valid_region().

This function controls if the region contains at least min_region_size points.

Parameters

region indices of points included in the region

Returns: Boolean true or false

◆ update()

template<typename GeomTraits , typename InputRange , typename PointMap , typename NormalMap >

void CGAL::Shape_detection::Point_set::Least_squares_line_fit_region< GeomTraits, InputRange, PointMap, NormalMap >::update ( const std::vector< std::size_t > & region )

implements RegionType::update().

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

Parameters

region indices of points included in the region

Precondition: region.size() > 0

Definition

Types

Initialization

Access

Constructor & Destructor Documentation

◆ Least_squares_line_fit_region()

Member Function Documentation

◆ is_part_of_region()

◆ is_valid_region()

◆ update()