#include <visp3/core/vpMomentCInvariant.h>

Inheritance diagram for vpMomentCInvariant:

Public Member Functions
	vpMomentCInvariant (bool flg_sxsynormalization=false)

double	C1 () const

double	C2 () const

double	C3 () const

double	C4 () const

double	C5 () const

double	C6 () const

double	C7 () const

double	C8 () const

double	C9 () const

double	C10 () const

void	compute ()

double	get (unsigned int i) const

double	getC (unsigned int i) const

double	getI (unsigned int index) const

void	printInvariants (std::ostream &os) const

double	getII (unsigned int i) const

double	getK () const

double	getS (unsigned int i) const

const std::string	name () const

void	printI (unsigned int index)

double	Px ()

double	Py ()

double	Sx () const

double	Sy () const

double	getIn1 () const

double	getCN (unsigned int i) const

double	getSN (unsigned int i) const

bool	isSxSyfromNormalizedMoments () const

const std::vector< double > &	getMomentVector () const

Inherited functionalities from vpMoment
const vpMomentObject &	getObject () const

const std::vector< double > &	get () const

void	linkTo (vpMomentDatabase &moments)

virtual void	printDependencies (std::ostream &os) const

void	update (vpMomentObject &object)

Protected Member Functions
vpMomentDatabase &	getMoments () const

Protected Attributes
std::vector< double >	values

Friends
VISP_EXPORT std::ostream &	operator<< (std::ostream &os, const vpMomentCInvariant &v)

Detailed Description

This class defines several 2D (translation+rotation+scale) invariants for both symmetric and non-symmetric objects. These moment-based invariants are described in the following papers [6], [46].

The descriptions for the invariants $C_1$ to $C_{10}$ can be found in [6] and for invariants $P_x$ , $P_y$ , $S_x$ , $S_y$ in [46].

These invariants are classicaly used in visual servoing to control the out-of-plane rotations. The C-type or P-type invariants are used for non-symmetric objects whereas the S-type invariants are used for symmetric objects.

For most cases of non-symmetric objects, ( $C_4$ , $C_6$ ) or ( $P_x$ , $P_y$ ) couples are widely used to control x and y rotations. For symmetric objects $S_x$ and $S_y$ are the only choice.

There are 14 translation+rotation+scale invariants (10 C-type, 2 P-type and 2 S-type) that can be accessed from by vpMomentCInvariant::get or any of the get shortcuts.

The example below shows how to retrieve the $C_2$ invariant:

#include <iostream>
#include <visp3/core/vpMomentCInvariant.h>
#include <visp3/core/vpMomentCommon.h>
#include <visp3/core/vpMomentObject.h>
#include <visp3/core/vpPoint.h>
 
int main()
{
  vpPoint p;
  std::vector<vpPoint> vec_p;
 
  p.set_x(6); p.set_y(-1); // coordinates in meters in the image plane (vertex 1)
  vec_p.push_back(p);
  p.set_x(2); p.set_y(3); // coordinates in meters in the image plane (vertex 2)
  vec_p.push_back(p);
  p.set_x(0); p.set_y(1.2); // coordinates in meters in the image plane (vertex 1)
  vec_p.push_back(p);
  p.set_x(-7); p.set_y(-4); // coordinates in meters in the image plane (vertex 2)
  vec_p.push_back(p);
 
  vpMomentObject obj(5); // Create an image moment object with 5 as maximum order
  obj.setType(vpMomentObject::DISCRETE); // Discrete mode for object
  obj.fromVector(vec_p);
 
  //initialisation with default values
  vpMomentCommon db(vpMomentCommon::getSurface(obj),vpMomentCommon::getMu3(obj),
                    vpMomentCommon::getAlpha(obj),1.);
  bool success;
 
  db.updateAll(obj); // Update AND compute all moments
 
  //get C-invariant
  const vpMomentCInvariant& C
    = static_cast<const vpMomentCInvariant&>(db.get("vpMomentCInvariant",success));
  if(success)
      std::cout << C.get(1) << std:: endl; // print C2 invariant
  else
      std::cout << "vpMomentCInvariant not found." << std::endl;
 
  return 0;
}

vpMomentCInvariant depends on vpMomentCentered (see vpMomentDatabase and vpMomentCommon).

Definition at line 122 of file vpMomentCInvariant.h.

Constructor & Destructor Documentation

◆ vpMomentCInvariant()

vpMomentCInvariant::vpMomentCInvariant ( bool flg_sxsynormalization = false )

explicit

Default constructor. (option to use a different calculation mode for sx and sy)

Definition at line 48 of file vpMomentCInvariant.cpp.

References vpMoment::values.

Member Function Documentation

◆ C1()

double vpMomentCInvariant::C1 ( ) const

inline

Shorcut for getting the value of $C_1$ .

Definition at line 147 of file vpMomentCInvariant.h.

◆ C10()

double vpMomentCInvariant::C10 ( ) const

inline

Shorcut for getting the value of $C_{10}$ .

Definition at line 183 of file vpMomentCInvariant.h.

◆ C2()

double vpMomentCInvariant::C2 ( ) const

inline

Shorcut for getting the value of $C_2$ .

Definition at line 151 of file vpMomentCInvariant.h.

◆ C3()

double vpMomentCInvariant::C3 ( ) const

inline

Shorcut for getting the value of $C_3$ .

Definition at line 155 of file vpMomentCInvariant.h.

◆ C4()

double vpMomentCInvariant::C4 ( ) const

inline

Shorcut for getting the value of $C_4$ .

Definition at line 159 of file vpMomentCInvariant.h.

◆ C5()

double vpMomentCInvariant::C5 ( ) const

inline

Shorcut for getting the value of $C_5$ .

Definition at line 163 of file vpMomentCInvariant.h.

◆ C6()

double vpMomentCInvariant::C6 ( ) const

inline

Shorcut for getting the value of $C_6$ .

Definition at line 167 of file vpMomentCInvariant.h.

◆ C7()

double vpMomentCInvariant::C7 ( ) const

inline

Shorcut for getting the value of $C_7$ .

Definition at line 171 of file vpMomentCInvariant.h.

◆ C8()

double vpMomentCInvariant::C8 ( ) const

inline

Shorcut for getting the value of $C_8$ .

Definition at line 175 of file vpMomentCInvariant.h.

◆ C9()

double vpMomentCInvariant::C9 ( ) const

inline

Shorcut for getting the value of $C_9$ .

Definition at line 179 of file vpMomentCInvariant.h.

◆ compute()

void vpMomentCInvariant::compute ( )

virtual

Computes translation-plane-rotation-scale invariants. Depends on vpMomentCentered. All possible invariants are computed here. The selection of the invariant is done afterwards.

Implements vpMoment.

Definition at line 195 of file vpMomentCInvariant.cpp.

References vpMomentObject::DISCRETE, vpMomentObject::get(), vpMomentDatabase::get(), vpMomentCentered::get(), vpMoment::getMoments(), vpMoment::getObject(), vpException::notInitialized, and vpMoment::values.

Referenced by vpMomentCommon::updateAll().

◆ get() [1/2]

const std::vector<double>& vpMoment::get ( ) const

inlineinherited

Returns all values computed by the moment.

Returns: vector of values

Definition at line 149 of file vpMoment.h.

Referenced by vpMomentGravityCenterNormalized::compute(), vpFeatureMomentArea::compute_interaction(), vpFeatureMomentAreaNormalized::compute_interaction(), vpFeatureMomentGravityCenterNormalized::compute_interaction(), vpMomentCentered::get(), vpFeatureMoment::init(), vpMomentGravityCenterNormalized::printDependencies(), and vpFeatureMoment::update().

◆ get() [2/2]

double vpMomentCInvariant::get ( unsigned int i ) const

inline

Gets the desired invariant.

Parameters

i	given index. For invariants from C1 to C10 the corresponding index is from 0 to 9. For , the indexes are 10,11 and for , they are 12,13.

Definition at line 193 of file vpMomentCInvariant.h.

◆ getC()

double vpMomentCInvariant::getC ( unsigned int i ) const

inline

Access to partial invariant c (see [2]).

Definition at line 198 of file vpMomentCInvariant.h.

Referenced by vpFeatureMomentCInvariant::compute_interaction().

◆ getCN()

double vpMomentCInvariant::getCN ( unsigned int i ) const

inline

Getter for c (calculated from normalized 2nd and 3ord order moments)

Definition at line 261 of file vpMomentCInvariant.h.

◆ getI()

double vpMomentCInvariant::getI ( unsigned int index ) const

inline

Access to partial invariants. The index convention is the same as in [1].

Definition at line 202 of file vpMomentCInvariant.h.

Referenced by vpFeatureMomentCInvariant::compute_interaction().

◆ getII()

double vpMomentCInvariant::getII ( unsigned int i ) const

inline

Access to partial invariant I (see [2]).

Definition at line 212 of file vpMomentCInvariant.h.

Referenced by vpFeatureMomentCInvariant::compute_interaction().

◆ getIn1()

double vpMomentCInvariant::getIn1 ( ) const

inline

Getters for I (calculated from normalized 2nd and 3ord order moments)

Definition at line 255 of file vpMomentCInvariant.h.

◆ getK()

double vpMomentCInvariant::getK ( ) const

inline

Access to partial invariant K (see [2]).

Definition at line 216 of file vpMomentCInvariant.h.

◆ getMoments()

vpMomentDatabase& vpMoment::getMoments ( ) const

inlineprotectedinherited

Returns the linked moment database.

Returns: the moment database

Definition at line 117 of file vpMoment.h.

Referenced by vpMomentAlpha::compute(), vpMomentArea::compute(), vpMomentAreaNormalized::compute(), vpMomentCentered::compute(), compute(), vpMomentGravityCenterNormalized::compute(), vpMomentAlpha::printDependencies(), vpMomentArea::printDependencies(), vpMomentAreaNormalized::printDependencies(), vpMomentCentered::printDependencies(), and vpMomentGravityCenterNormalized::printDependencies().

◆ getMomentVector()

const std::vector<double>& vpMomentCInvariant::getMomentVector ( ) const

inline

To get all the invariant values as a whole.

Definition at line 277 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ getObject()

const vpMomentObject& vpMoment::getObject ( ) const

inlineinherited

Definition at line 144 of file vpMoment.h.

◆ getS()

double vpMomentCInvariant::getS ( unsigned int i ) const

inline

Access to partial invariant S (see [2]).

Definition at line 221 of file vpMomentCInvariant.h.

Referenced by vpFeatureMomentCInvariant::compute_interaction().

◆ getSN()

double vpMomentCInvariant::getSN ( unsigned int i ) const

inline

Getter for s (calculated from normalized 2nd and 3ord order moments)

Definition at line 267 of file vpMomentCInvariant.h.

◆ isSxSyfromNormalizedMoments()

bool vpMomentCInvariant::isSxSyfromNormalizedMoments ( ) const

inline

To know if Sx and Sy were calculated from normalized moments or not

Definition at line 272 of file vpMomentCInvariant.h.

◆ linkTo()

void vpMoment::linkTo ( vpMomentDatabase & data_base )

inherited

Links the moment to a database of moment primitives. If the moment depends on other moments, these moments must be linked to the same database.

Attention: Two moments of the same class cannot be stored in the same database
#include <visp3/core/vpMomentCentered.h>

#include <visp3/core/vpMomentDatabase.h>

#include <visp3/core/vpMomentGravityCenter.h>

#include <visp3/core/vpMomentObject.h>

#include <visp3/core/vpPoint.h>

int main()

{

vpPoint p;

std::vector<vpPoint> vec_p;

p.set_x(1); p.set_y(1); // coordinates in meters in the image plane (vertex 1)

vec_p.push_back(p);

p.set_x(2); p.set_y(2); // coordinates in meters in the image plane (vertex 2)

vec_p.push_back(p);

vpMomentObject obj(2);

obj.setType(vpMomentObject::DISCRETE); // Discrete mode.

obj.fromVector(vec_p); // Init the dense object with the polygon

vpMomentDatabase db;

vpMomentGravityCenter G; // declaration of gravity center

vpMomentCentered mc; // mc contains centered moments

G.linkTo(db); // add gravity center to database

mc.linkTo(db); // centered moments depend on gravity, add them to the

// database to grant access

G.update(obj); // specify the object for gravity center

mc.update(obj); // and for centered moments

G.compute(); // compute the moment

mc.compute(); // compute centered moments AFTER gravity center

return 0;

}

vpMomentCentered
This class defines the double-indexed centered moment descriptor .
Definition: vpMomentCentered.h:75

vpMomentCentered::compute
void compute()
Definition: vpMomentCentered.cpp:65

vpMomentDatabase
This class allows to register all vpMoments so they can access each other according to their dependen...
Definition: vpMomentDatabase.h:128

vpMomentGravityCenter
Class describing 2D gravity center moment.
Definition: vpMomentGravityCenter.h:109

vpMomentGravityCenter::compute
void compute()
Definition: vpMomentGravityCenter.cpp:45

vpMoment::linkTo
void linkTo(vpMomentDatabase &moments)
Definition: vpMoment.cpp:95

vpMoment::update
void update(vpMomentObject &object)
Definition: vpMoment.cpp:108

Parameters

data_base : database of moment primitives.

Examples: mbot-apriltag-ibvs.cpp, servoBebop2.cpp, and testMomentAlpha.cpp.

Definition at line 95 of file vpMoment.cpp.

References vpMoment::name().

Referenced by vpMomentCommon::getAlpha(), vpMomentCommon::getMu3(), vpMomentCommon::getSurface(), and vpMomentCommon::vpMomentCommon().

◆ name()

const std::string vpMomentCInvariant::name ( ) const

inlinevirtual

Moment name.

Implements vpMoment.

Definition at line 226 of file vpMomentCInvariant.h.

◆ printDependencies()

void vpMoment::printDependencies ( std::ostream & os ) const

virtualinherited

Prints values of all dependent moments required to calculate a specific vpMoment. Not made pure to maintain compatibility Recommended : Types inheriting from vpMoment should implement this function

Reimplemented in vpMomentGravityCenterNormalized, vpMomentGravityCenter, vpMomentCentered, vpMomentBasic, vpMomentAreaNormalized, vpMomentArea, and vpMomentAlpha.

Definition at line 128 of file vpMoment.cpp.

◆ printI()

void vpMomentCInvariant::printI ( unsigned int index )

Print partial invariant.

Prints the temporary invariants. Used for debug purposes only

Parameters

index : index of the temporary invariant

Definition at line 269 of file vpMomentCInvariant.cpp.

◆ printInvariants()

void vpMomentCInvariant::printInvariants ( std::ostream & os ) const

Print the moment invariants used to obtain the actual visual features

Print out all invariants that were computed There are 15 of them, as in [Point-based and region based.ITRO05] [46]

Definition at line 276 of file vpMomentCInvariant.cpp.

◆ Px()

double vpMomentCInvariant::Px ( )

inline

Shorcut for getting the value of $P_x$ .

Definition at line 236 of file vpMomentCInvariant.h.

◆ Py()

double vpMomentCInvariant::Py ( )

inline

Shorcut for getting the value of $P_y$ .

Definition at line 240 of file vpMomentCInvariant.h.

◆ Sx()

double vpMomentCInvariant::Sx ( ) const

inline

Shorcut for getting the value of $S_x$ .

Definition at line 245 of file vpMomentCInvariant.h.

◆ Sy()

double vpMomentCInvariant::Sy ( ) const

inline

Shorcut for getting the value of $S_y$ .

Definition at line 249 of file vpMomentCInvariant.h.

◆ update()

void vpMoment::update ( vpMomentObject & moment_object )

inherited

Updates the moment with the current object. This does not compute any values.

Parameters

moment_object : object descriptor of the current camera vision.

Definition at line 108 of file vpMoment.cpp.

Friends And Related Function Documentation

◆ operator<<

VISP_EXPORT std::ostream& operator<<	(	std::ostream &	os,
		const vpMomentCInvariant &	v
	)

friend

Outputs the moment's values to a stream.

Definition at line 288 of file vpMomentCInvariant.cpp.

Member Data Documentation

◆ values

std::vector<double> vpMoment::values

protectedinherited

Definition at line 112 of file vpMoment.h.

Referenced by vpMomentAlpha::compute(), vpMomentArea::compute(), vpMomentAreaNormalized::compute(), vpMomentCentered::compute(), compute(), vpMomentGravityCenter::compute(), vpMomentGravityCenterNormalized::compute(), vpMomentGravityCenter::get(), vpMomentCentered::get(), getMomentVector(), vpMomentCentered::set(), vpMomentAlpha::vpMomentAlpha(), vpMomentArea::vpMomentArea(), vpMomentAreaNormalized::vpMomentAreaNormalized(), vpMomentCInvariant(), and vpMomentGravityCenter::vpMomentGravityCenter().

Public Member Functions

Protected Member Functions

Protected Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

◆ vpMomentCInvariant()

Member Function Documentation

◆ C1()

◆ C10()

◆ C2()

◆ C3()

◆ C4()

◆ C5()

◆ C6()

◆ C7()

◆ C8()

◆ C9()

◆ compute()

◆ get() [1/2]

◆ get() [2/2]

◆ getC()

◆ getCN()

◆ getI()

◆ getII()

◆ getIn1()

◆ getK()

◆ getMoments()

◆ getMomentVector()

◆ getObject()

◆ getS()

◆ getSN()

◆ isSxSyfromNormalizedMoments()

◆ linkTo()

◆ name()

◆ printDependencies()

◆ printI()

◆ printInvariants()

◆ Px()

◆ Py()

◆ Sx()

◆ Sy()

◆ update()

Friends And Related Function Documentation

◆ operator<<

Member Data Documentation

◆ values