Visual Servoing Platform version 3.7.0
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vpMomentCInvariant Class Reference
core: Core module » Tools » Image moments

#include <vpMomentCInvariant.h>

Inheritance diagram for vpMomentCInvariant:

Public Member Functions

VP_EXPLICIT 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 () VP_OVERRIDE
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 VP_OVERRIDE
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], [54].

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 [54].

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>
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
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::vpMomentCInvariant
VP_EXPLICIT vpMomentCInvariant(bool flg_sxsynormalization=false)
Definition vpMomentCInvariant.cpp:44
vpMomentCInvariant::get
double get(unsigned int i) const
Definition vpMomentCInvariant.h:199
vpMomentCommon
This class initializes and allows access to commonly used moments.
Definition vpMomentCommon.h:102
vpMomentCommon::getMu3
static std::vector< double > getMu3(vpMomentObject &object)
Definition vpMomentCommon.cpp:201
vpMomentCommon::getAlpha
static double getAlpha(vpMomentObject &object)
Definition vpMomentCommon.cpp:178
vpMomentCommon::getSurface
static double getSurface(vpMomentObject &object)
Definition vpMomentCommon.cpp:151
vpMomentObject
Class for generic objects.
Definition vpMomentObject.h:225
vpPoint
Class that defines a 3D point in the object frame and allows forward projection of a 3D point in the ...
Definition vpPoint.h:79
VISP_NAMESPACE_NAME
Definition vpEigenConversion.h:44

vpMomentCInvariant depends on vpMomentCentered (see vpMomentDatabase and vpMomentCommon).

Definition at line 128 of file vpMomentCInvariant.h.

Constructor & Destructor Documentation

◆ vpMomentCInvariant()

BEGIN_VISP_NAMESPACE vpMomentCInvariant::vpMomentCInvariant ( bool flg_sxsynormalization = false)

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

Definition at line 44 of file vpMomentCInvariant.cpp.

References vpMoment::values.

Referenced by operator<<.

Member Function Documentation

◆ C1()

double vpMomentCInvariant::C1 ( ) const
inline

Shorcut for getting the value of $C_1$.

Definition at line 153 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ C10()

double vpMomentCInvariant::C10 ( ) const
inline

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

Definition at line 189 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ C2()

double vpMomentCInvariant::C2 ( ) const
inline

Shorcut for getting the value of $C_2$.

Definition at line 157 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ C3()

double vpMomentCInvariant::C3 ( ) const
inline

Shorcut for getting the value of $C_3$.

Definition at line 161 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ C4()

double vpMomentCInvariant::C4 ( ) const
inline

Shorcut for getting the value of $C_4$.

Definition at line 165 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ C5()

double vpMomentCInvariant::C5 ( ) const
inline

Shorcut for getting the value of $C_5$.

Definition at line 169 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ C6()

double vpMomentCInvariant::C6 ( ) const
inline

Shorcut for getting the value of $C_6$.

Definition at line 173 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ C7()

double vpMomentCInvariant::C7 ( ) const
inline

Shorcut for getting the value of $C_7$.

Definition at line 177 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ C8()

double vpMomentCInvariant::C8 ( ) const
inline

Shorcut for getting the value of $C_8$.

Definition at line 181 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ C9()

double vpMomentCInvariant::C9 ( ) const
inline

Shorcut for getting the value of $C_9$.

Definition at line 185 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ 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 192 of file vpMomentCInvariant.cpp.

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

◆ 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 155 of file vpMoment.h.

References values.

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

◆ get() [2/2]

double vpMomentCInvariant::get ( unsigned int i) const
inline

Gets the desired invariant.

Parameters
igiven index. For invariants from C1 to C10 the corresponding index is from 0 to 9. For $S_x$, $S_y$ the indexes are 10,11 and for $P_x$, $P_y$ they are 12,13.

Definition at line 199 of file vpMomentCInvariant.h.

References get(), and vpMoment::values.

Referenced by get().

◆ getC()

double vpMomentCInvariant::getC ( unsigned int i) const
inline

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

Definition at line 204 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 267 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 208 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 218 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 261 of file vpMomentCInvariant.h.

◆ getK()

double vpMomentCInvariant::getK ( ) const
inline

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

Definition at line 222 of file vpMomentCInvariant.h.

◆ getMoments()

vpMomentDatabase & vpMoment::getMoments ( ) const
inlineprotectedinherited

Returns the linked moment database.

Returns
the moment database

Definition at line 118 of file vpMoment.h.

Referenced by vpMomentAlpha::compute(), vpMomentArea::compute(), vpMomentAreaNormalized::compute(), vpMomentCentered::compute(), vpMomentCInvariant::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 283 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ getObject()

const vpMomentObject & vpMoment::getObject ( ) const
inlineinherited

Definition at line 150 of file vpMoment.h.

Referenced by vpMomentArea::compute(), vpMomentAreaNormalized::compute(), vpMomentCentered::compute(), vpMomentCInvariant::compute(), vpMomentGravityCenter::compute(), vpMomentBasic::get(), vpMomentBasic::get(), vpMomentCentered::get(), vpMomentBasic::operator<<, vpMomentCentered::operator<<, vpMomentArea::printDependencies(), vpMomentAreaNormalized::printDependencies(), vpMomentBasic::printDependencies(), vpMomentCentered::printDependencies(), vpMomentGravityCenter::printDependencies(), vpMomentCentered::printWithIndices(), and vpMomentCentered::set().

◆ getS()

double vpMomentCInvariant::getS ( unsigned int i) const
inline

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

Definition at line 227 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 273 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 278 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>
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
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:77
vpMomentCentered::compute
void compute() VP_OVERRIDE
Definition vpMomentCentered.cpp:61
vpMomentDatabase
This class allows to register all vpMoments so they can access each other according to their dependen...
Definition vpMomentDatabase.h:133
vpMomentGravityCenter
Class describing 2D gravity center moment.
Definition vpMomentGravityCenter.h:117
vpMoment::linkTo
void linkTo(vpMomentDatabase &moments)
Definition vpMoment.cpp:114
vpMoment::update
void update(vpMomentObject &object)
Definition vpMoment.cpp:127
Parameters
data_base: database of moment primitives.
Examples
mbot-apriltag-ibvs.cpp, servoBebop2.cpp, servoPixhawkDroneIBVS.cpp, and testMomentAlpha.cpp.

Definition at line 114 of file vpMoment.cpp.

References name().

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

◆ name()

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

Moment name.

Implements vpMoment.

Definition at line 232 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 vpMomentAlpha, vpMomentArea, vpMomentAreaNormalized, vpMomentBasic, vpMomentCentered, vpMomentGravityCenter, and vpMomentGravityCenterNormalized.

Definition at line 134 of file vpMoment.cpp.

Referenced by name().

◆ 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 266 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] [54]

Definition at line 273 of file vpMomentCInvariant.cpp.

◆ Px()

double vpMomentCInvariant::Px ( )
inline

Shorcut for getting the value of $P_x$.

Definition at line 242 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ Py()

double vpMomentCInvariant::Py ( )
inline

Shorcut for getting the value of $P_y$.

Definition at line 246 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ Sx()

double vpMomentCInvariant::Sx ( ) const
inline

Shorcut for getting the value of $S_x$.

Definition at line 251 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ Sy()

double vpMomentCInvariant::Sy ( ) const
inline

Shorcut for getting the value of $S_y$.

Definition at line 255 of file vpMomentCInvariant.h.

References vpMoment::values.

◆ 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 127 of file vpMoment.cpp.

Referenced by name().

◆ operator<<

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

Outputs the moment's values to a stream.

Definition at line 285 of file vpMomentCInvariant.cpp.

References vpMomentCInvariant().

Member Data Documentation

◆ values

std::vector<double> vpMoment::values
protectedinherited

Definition at line 113 of file vpMoment.h.

Referenced by vpMomentCInvariant::C1(), vpMomentCInvariant::C10(), vpMomentCInvariant::C2(), vpMomentCInvariant::C3(), vpMomentCInvariant::C4(), vpMomentCInvariant::C5(), vpMomentCInvariant::C6(), vpMomentCInvariant::C7(), vpMomentCInvariant::C8(), vpMomentCInvariant::C9(), vpMomentAlpha::compute(), vpMomentArea::compute(), vpMomentAreaNormalized::compute(), vpMomentCentered::compute(), vpMomentCInvariant::compute(), vpMomentGravityCenter::compute(), vpMomentGravityCenterNormalized::compute(), get(), vpMomentAlpha::get(), vpMomentCentered::get(), vpMomentCInvariant::get(), vpMomentGravityCenter::get(), vpMomentCInvariant::getMomentVector(), vpMomentGravityCenter::getXg(), vpMomentGravityCenter::getYg(), operator<<, vpMomentAlpha::operator<<, vpMomentArea::operator<<, vpMomentAreaNormalized::operator<<, vpMomentCentered::operator<<, vpMomentGravityCenter::operator<<, vpMomentGravityCenterNormalized::operator<<, vpMomentCInvariant::Px(), vpMomentCInvariant::Py(), vpMomentCentered::set(), vpMomentCInvariant::Sx(), vpMomentCInvariant::Sy(), vpMoment(), vpMomentAlpha::vpMomentAlpha(), vpMomentArea::vpMomentArea(), vpMomentAreaNormalized::vpMomentAreaNormalized(), vpMomentCInvariant::vpMomentCInvariant(), and vpMomentGravityCenter::vpMomentGravityCenter().