Aim: On-line recognition of a digital straight segment (DSS) defined as a sequence of connected grid edges such that there is at least one straight line that separates the centers of the two incident pixels of each grid edge. More...

#include <DGtal/geometry/curves/StabbingLineComputer.h>

Public Types
typedef TConstIterator	ConstIterator

typedef StabbingLineComputer< ConstIterator >	Self

typedef StabbingLineComputer< ReverseIterator< ConstIterator > >	Reverse

typedef IteratorCirculatorTraits< ConstIterator >::Value	Pair

typedef Pair::first_type	Point

typedef StraightLineFrom2Points< Point >	StraightLine

typedef Preimage2D< StraightLine >	Preimage

typedef CowPtr< Preimage >	PreimagePtr

Public Member Functions
	BOOST_STATIC_ASSERT ((concepts::ConceptUtils::SameType< typename Pair::first_type, typename Pair::second_type > ::value))

	StabbingLineComputer ()

	StabbingLineComputer (const Self &other)

Self &	operator= (const Self &other)

	~StabbingLineComputer ()

bool	operator== (const Self &other) const

bool	operator!= (const Self &other) const

Self	getSelf () const

Reverse	getReverse () const

bool	isValid () const

ConstIterator	begin () const

ConstIterator	end () const

Point	Uf () const

Point	Ul () const

Point	Lf () const

Point	Ll () const

PreimagePtr	getPreimage () const

bool	isClockwiseOriented () const

void	getParameters (double &alpha, double &beta, double &gamma) const

void	projects (double &x, double &y, const double &alpha, const double &beta, const double &gamma) const

void	init (const ConstIterator &anIt)

bool	extendFront ()

bool	isExtendableFront ()

bool	isConcave ()

bool	isConvex ()

bool	extendBack ()

bool	isExtendableBack ()

bool	isOppositeEndConcave ()

bool	isOppositeEndConvex ()

void	selfDisplay (std::ostream &out) const

std::string	className () const

Private Attributes
ConstIterator	myBegin

ConstIterator	myEnd

PreimagePtr	myPreimagePtr

bool	myFlagIsInit

bool	myFlagIsCW

Detailed Description

template<typename TConstIterator>
class DGtal::StabbingLineComputer< TConstIterator >

Aim: On-line recognition of a digital straight segment (DSS) defined as a sequence of connected grid edges such that there is at least one straight line that separates the centers of the two incident pixels of each grid edge.

Note: On either side, the pixels centers are included. The class of segments considered here is thus larger than the one considered in ArithmeticalDSSComputer (the equivalence would be true if the pixels centers were included on one side but excluded on the other side)

The algorithm computes and maintains the preimage of the whole set of separating straight lines in linear time using Preimage2D and the algorithm of O'Rourke (1981).

Note: Joseph O'Rourke, An on-line algorithm for fitting straight lines between data ranges, Communications of the ACM, Volume 24, Issue 9, September 1981, 574–578.

This class is a model of the concept CBidirectionalSegmentComputer.

It should be used with the Curve object (defined in StdDefs.h) and its IncidentPointsRange as follows:

  Curve::IncidentPointsRange r = c.getIncidentPointsRange(); 
  Curve::IncidentPointsRange::ConstIterator itEnd (r.end()); 
 
  StabbingLineComputer<Curve::IncidentPointsRange::ConstIterator> s; 
  //extension
  s.init( r.begin() );
  while ( ( s.end() != itEnd )
        &&( s.extendFront() ) ) {}

Template Parameters

TConstIterator ConstIterator type on STL pairs of 2D points

See also: testStabbingLineComputer.cpp exampleStabbingLineComputer.cpp Preimage2D ArithmeticalDSSComputer

Definition at line 92 of file StabbingLineComputer.h.

Member Typedef Documentation

◆ ConstIterator

template<typename TConstIterator >

typedef TConstIterator DGtal::StabbingLineComputer< TConstIterator >::ConstIterator

Definition at line 98 of file StabbingLineComputer.h.

◆ Pair

template<typename TConstIterator >

typedef IteratorCirculatorTraits<ConstIterator>::Value DGtal::StabbingLineComputer< TConstIterator >::Pair

Definition at line 103 of file StabbingLineComputer.h.

◆ Point

template<typename TConstIterator >

typedef Pair::first_type DGtal::StabbingLineComputer< TConstIterator >::Point

Definition at line 104 of file StabbingLineComputer.h.

◆ Preimage

template<typename TConstIterator >

typedef Preimage2D<StraightLine> DGtal::StabbingLineComputer< TConstIterator >::Preimage

Definition at line 113 of file StabbingLineComputer.h.

◆ PreimagePtr

template<typename TConstIterator >

typedef CowPtr<Preimage> DGtal::StabbingLineComputer< TConstIterator >::PreimagePtr

Definition at line 114 of file StabbingLineComputer.h.

◆ Reverse

template<typename TConstIterator >

typedef StabbingLineComputer<ReverseIterator<ConstIterator> > DGtal::StabbingLineComputer< TConstIterator >::Reverse

Definition at line 100 of file StabbingLineComputer.h.

◆ Self

template<typename TConstIterator >

typedef StabbingLineComputer<ConstIterator> DGtal::StabbingLineComputer< TConstIterator >::Self

Definition at line 99 of file StabbingLineComputer.h.

◆ StraightLine

template<typename TConstIterator >

typedef StraightLineFrom2Points<Point> DGtal::StabbingLineComputer< TConstIterator >::StraightLine

Definition at line 112 of file StabbingLineComputer.h.

Constructor & Destructor Documentation

◆ StabbingLineComputer() [1/2]

template<typename TConstIterator >

DGtal::StabbingLineComputer< TConstIterator >::StabbingLineComputer ( )

Constructor.

◆ StabbingLineComputer() [2/2]

template<typename TConstIterator >

DGtal::StabbingLineComputer< TConstIterator >::StabbingLineComputer ( const Self & other )

Copy constructor.

Parameters

other the object to clone.

◆ ~StabbingLineComputer()

template<typename TConstIterator >

DGtal::StabbingLineComputer< TConstIterator >::~StabbingLineComputer ( )

Destructor.

Member Function Documentation

◆ begin()

template<typename TConstIterator >

ConstIterator DGtal::StabbingLineComputer< TConstIterator >::begin ( ) const

Returns: segment begin iterator.

Referenced by testStabbingLineComputer().

◆ BOOST_STATIC_ASSERT()

template<typename TConstIterator >

DGtal::StabbingLineComputer< TConstIterator >::BOOST_STATIC_ASSERT ( (concepts::ConceptUtils::SameType< typename Pair::first_type, typename Pair::second_type > ::value) )

◆ className()

template<typename TConstIterator >

std::string DGtal::StabbingLineComputer< TConstIterator >::className ( ) const

Default drawing style object.

Returns: the dyn. alloc. default style for this object.; the style name used for drawing this object.

◆ end()

template<typename TConstIterator >

ConstIterator DGtal::StabbingLineComputer< TConstIterator >::end ( ) const

Returns: segment end iterator.

Referenced by testStabbingLineComputer().

◆ extendBack()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::extendBack ( )

Backward extension of the segment.

Returns: 'true' if the segment is extended and 'false' otherwise.

Referenced by testStabbingLineComputer().

◆ extendFront()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::extendFront ( )

Forward extension of the segment.

Returns: 'true' if the segment is extended and 'false' otherwise.

Referenced by testStabbingLineComputer().

◆ getParameters()

template<typename TConstIterator >

void DGtal::StabbingLineComputer< TConstIterator >::getParameters	(	double &	alpha,
		double &	beta,
		double &	gamma
	)		const

Get the parameters of one separating straight line

Parameters

alpha	(returned) x-component of the normal
beta	(returned) y-component of the normal
gamma	(returned) intercept

Referenced by testStabbingLineComputer().

◆ getPreimage()

template<typename TConstIterator >

PreimagePtr DGtal::StabbingLineComputer< TConstIterator >::getPreimage ( ) const

Returns: the preimage

◆ getReverse()

template<typename TConstIterator >

Reverse DGtal::StabbingLineComputer< TConstIterator >::getReverse ( ) const

Returns: a default-constructed instance of Reverse.

Referenced by testStabbingLineComputer().

◆ getSelf()

template<typename TConstIterator >

Self DGtal::StabbingLineComputer< TConstIterator >::getSelf ( ) const

Returns: a default-constructed instance of Self

◆ init()

template<typename TConstIterator >

void DGtal::StabbingLineComputer< TConstIterator >::init ( const ConstIterator & anIt )

Segment initialization

Parameters

anIt	any iterator

Referenced by main(), and testStabbingLineComputer().

◆ isClockwiseOriented()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::isClockwiseOriented ( ) const

Returns: 'true' if CW, 'false' if CCW

◆ isConcave()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::isConcave ( )

Decide whether the extension of the segment would result in a concave part or not.

Returns: 'true' if the extension of the segment results in a concave part and 'false' otherwise.

NB: a true returned value implies that isExtendableFront() returns 'false'

◆ isConvex()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::isConvex ( )

Decide whether the extension of the segment would result in a convex part or not.

Returns: 'true' if the extension of the segment results in a convex part and 'false' otherwise.

NB: a true returned value implies that isExtendableFront() returns 'false'

◆ isExtendableBack()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::isExtendableBack ( )

Backward extension test.

Returns: 'true' if the segment can be extended and 'false' otherwise.

◆ isExtendableFront()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::isExtendableFront ( )

Forward extension test.

Returns: 'true' if the segment can be extended and 'false' otherwise.

Referenced by testStabbingLineComputer().

◆ isOppositeEndConcave()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::isOppositeEndConcave ( )

Decide whether the extension of the segment would result in a concave part or not.

Returns: 'true' if the extension of the segment results in a concave part and 'false' otherwise.

NB: a true returned value implies that isExtendableBack() returns 'false'

◆ isOppositeEndConvex()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::isOppositeEndConvex ( )

Decide whether the extension of the segment would result in a convex part or not.

Returns: 'true' if the extension of the segment results in a convex part and 'false' otherwise.

NB: a true returned value implies that isExtendableBack() returns 'false'

◆ isValid()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::isValid ( ) const

Checks the validity/consistency of the object.

Returns: 'true' if the object is valid, 'false' otherwise.

Referenced by testStabbingLineComputer().

◆ Lf()

template<typename TConstIterator >

Point DGtal::StabbingLineComputer< TConstIterator >::Lf ( ) const

Returns: first lower leaning point.

Referenced by testStabbingLineComputer().

◆ Ll()

template<typename TConstIterator >

Point DGtal::StabbingLineComputer< TConstIterator >::Ll ( ) const

Returns: last lower leaning point.

Referenced by testStabbingLineComputer().

◆ operator!=()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::operator!= ( const Self & other ) const

Difference operator

Parameters

other the object to compare with.

Returns: 'true' if not equal, 'false' otherwise.

◆ operator=()

template<typename TConstIterator >

Self & DGtal::StabbingLineComputer< TConstIterator >::operator= ( const Self & other )

Assignment.

Parameters

other the object to copy.

Returns: a reference on 'this'.

◆ operator==()

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::operator== ( const Self & other ) const

Equality operator

Parameters

other the object to compare with.

Returns: 'true' if equal, 'false' otherwise

◆ projects()

template<typename TConstIterator >

void DGtal::StabbingLineComputer< TConstIterator >::projects	(	double &	x,
		double &	y,
		const double &	alpha,
		const double &	beta,
		const double &	gamma
	)		const

Projects the point ( x , y ) onto the straight line of parameters ( alpha , beta , gamma )

Parameters

x	(returned) x-coordinate of the point
y	(returned) y-coordinate of the point
alpha	x-component of the direction vector
beta	y-component of the direction vector
gamma	intercept

◆ selfDisplay()

template<typename TConstIterator >

void DGtal::StabbingLineComputer< TConstIterator >::selfDisplay ( std::ostream & out ) const

Writes/Displays the object on an output stream.

Parameters

out	the output stream where the object is written.

◆ Uf()

template<typename TConstIterator >

Point DGtal::StabbingLineComputer< TConstIterator >::Uf ( ) const

Returns: first upper leaning point.

Referenced by testStabbingLineComputer().

◆ Ul()

template<typename TConstIterator >

Point DGtal::StabbingLineComputer< TConstIterator >::Ul ( ) const

Returns: last upper leaning point.

Referenced by testStabbingLineComputer().

Field Documentation

◆ myBegin

template<typename TConstIterator >

ConstIterator DGtal::StabbingLineComputer< TConstIterator >::myBegin

private

segment begin iterator.

Definition at line 348 of file StabbingLineComputer.h.

◆ myEnd

template<typename TConstIterator >

ConstIterator DGtal::StabbingLineComputer< TConstIterator >::myEnd

private

segment end iterator.

Definition at line 352 of file StabbingLineComputer.h.

◆ myFlagIsCW

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::myFlagIsCW

private

Flag equal to 'true' if the pairs of points are clockwise oriented, 'false' otherwise.

Definition at line 366 of file StabbingLineComputer.h.

◆ myFlagIsInit

template<typename TConstIterator >

bool DGtal::StabbingLineComputer< TConstIterator >::myFlagIsInit

private

Flag equal to 'true' if the segment contains at least two pairs (the orientation is known) and 'false' otherwise.

Definition at line 361 of file StabbingLineComputer.h.

◆ myPreimagePtr

template<typename TConstIterator >

PreimagePtr DGtal::StabbingLineComputer< TConstIterator >::myPreimagePtr

private

Pointer to the preimage.

Definition at line 356 of file StabbingLineComputer.h.

The documentation for this class was generated from the following file:

StabbingLineComputer.h

Public Types

Public Member Functions

Private Attributes

Detailed Description

Member Typedef Documentation

◆ ConstIterator

◆ Pair

◆ Point

◆ Preimage

◆ PreimagePtr

◆ Reverse

◆ Self

◆ StraightLine

Constructor & Destructor Documentation

◆ StabbingLineComputer() [1/2]

◆ StabbingLineComputer() [2/2]

◆ ~StabbingLineComputer()

Member Function Documentation

◆ begin()

◆ BOOST_STATIC_ASSERT()

◆ className()

◆ end()

◆ extendBack()

◆ extendFront()

◆ getParameters()

◆ getPreimage()

◆ getReverse()

◆ getSelf()

◆ init()

◆ isClockwiseOriented()

◆ isConcave()

◆ isConvex()

◆ isExtendableBack()

◆ isExtendableFront()

◆ isOppositeEndConcave()

◆ isOppositeEndConvex()

◆ isValid()

◆ Lf()

◆ Ll()

◆ operator!=()

◆ operator=()

◆ operator==()

◆ projects()

◆ selfDisplay()

◆ Uf()

◆ Ul()

Field Documentation

◆ myBegin

◆ myEnd

◆ myFlagIsCW

◆ myFlagIsInit

◆ myPreimagePtr