#include <visp3/core/vpMomentCentered.h>

Inheritance diagram for vpMomentCentered:

Public Member Functions
	vpMomentCentered ()

void	compute ()

double	get (unsigned int i, unsigned int j) const

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

const std::string	name () const

void	printWithIndices (std::ostream &os) const

void	printDependencies (std::ostream &os) const

Inherited functionalities from vpMoment
const vpMomentObject &	getObject () const

void	linkTo (vpMomentDatabase &moments)

void	update (vpMomentObject &object)

Protected Member Functions
void	set (unsigned int i, unsigned int j, double value)

vpMomentDatabase &	getMoments () const

Protected Attributes
std::vector< double >	values

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

Detailed Description

This class defines the double-indexed centered moment descriptor $\mu_{ij}$ .

In the case of a dense object O, centered moments are defined by:

$\mu_{ij}= \int \int_{O} (x_k-x_g)^j (y_k-y_g)^j$

In the case of a discrete set of n points, centered moments are defined by:

$\mu_{ij}= \sum_{k=1}^{n} (x_k-x_g)^j (y_k-y_g)^j$

where $(x_g,y_g)$ are the coordinates of the center of gravity.

The centered moments are computed from the object at the highest possible order. For example if the vpMomentObject is defined up to order 5, vpMomentCentered will be too.

Values of vpMomentCentered may be accessed by one of the two vpMomentCentered::get methods. When using vpMomentCentered::get (), the format of the return vector is the following: $\mu_{ij}$ is stored at vpMomentCentered::get ()[j* (vpMomentObject::getOrder () +1)+i]

vpMomentCentered depends on vpMomentGravityCenter.

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

Definition at line 76 of file vpMomentCentered.h.

Constructor & Destructor Documentation

◆ vpMomentCentered()

vpMomentCentered::vpMomentCentered ( )

Default constructor.

Definition at line 96 of file vpMomentCentered.cpp.

Member Function Documentation

◆ compute()

void vpMomentCentered::compute ( )

virtual

Computes centered moments of all available orders. Depends on vpMomentGravityCenter.

Implements vpMoment.

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

Definition at line 66 of file vpMomentCentered.cpp.

References vpMath::comb(), vpMomentGravityCenter::get(), vpMomentObject::get(), vpMomentDatabase::get(), vpMoment::getMoments(), vpMoment::getObject(), vpMomentObject::getOrder(), vpException::notInitialized, and vpMoment::values.

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

◆ get() [1/2]

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

inline

Returns all centered moment values $\mu_{ij}$ with $i+j \leq order$ where order is the object's order.

Returns: Vector of moment values. To access $\mu_{ij}$ , you have to read vpMomentObject::get()[j*order+i].

For example, if the maximal order is 3, the following values are provided:

u00 u10 u20 u01 u11 u21 u02 u12 u12 u30 u03

To have a better reading of the moments you can picture them as a triangular matrix:

u00 u10 u20 u30 u01 u11 u21 x u02 u12 x x u30 x x x

The moments of the same order are on each of the matrix reverse diagonals. To access for example to the centered moment $\mu_{12}$ , you should use this kind of code:

vpMomentCentered mc;
//[...]
mc.compute();
double mu12;
mu12 = mc.get()[2*(obj.getOrder()+1)+1]; // i=1 and j=2
mu12 = mc.get(1,2); // the same

Definition at line 131 of file vpMomentCentered.h.

References vpMoment::get().

Referenced by printWithIndices().

◆ get() [2/2]

double vpMomentCentered::get	(	unsigned int	i,
		unsigned int	j
	)		const

Gets the desired moment using indexes.

Parameters

i	: first index of the centered moment.
j	: second index of the centered moment.

Returns: $\mu_{ij}$ moment.

Examples: testMomentAlpha.cpp.

Definition at line 104 of file vpMomentCentered.cpp.

References vpException::badValue, vpMoment::getObject(), vpMomentObject::getOrder(), and vpMoment::values.

Referenced by vpMomentAlpha::compute(), vpMomentArea::compute(), vpMomentAreaNormalized::compute(), vpMomentCInvariant::compute(), vpFeatureMomentAlpha::compute_interaction(), vpFeatureMomentAreaNormalized::compute_interaction(), vpFeatureMomentCentered::compute_interaction(), vpFeatureMomentCInvariant::compute_interaction(), vpFeatureMomentGravityCenter::compute_interaction(), vpFeatureMomentGravityCenterNormalized::compute_interaction(), vpMomentCommon::getMu3(), vpMomentCommon::getSurface(), vpMomentAlpha::printDependencies(), vpMomentArea::printDependencies(), and vpMomentAreaNormalized::printDependencies().

◆ 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(), compute(), vpMomentCInvariant::compute(), vpMomentGravityCenterNormalized::compute(), vpMomentAlpha::printDependencies(), vpMomentArea::printDependencies(), vpMomentAreaNormalized::printDependencies(), printDependencies(), and vpMomentGravityCenterNormalized::printDependencies().

◆ getObject()

const vpMomentObject& vpMoment::getObject ( ) const

inlineinherited

Definition at line 145 of file vpMoment.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;

}

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:116

vpMomentGravityCenter::compute
void compute()
Definition: vpMomentGravityCenter.cpp:47

vpMomentObject
Class for generic objects.
Definition: vpMomentObject.h:224

vpMomentObject::DISCRETE
@ DISCRETE
Definition: vpMomentObject.h:236

vpMoment::linkTo
void linkTo(vpMomentDatabase &moments)
Definition: vpMoment.cpp:114

vpMoment::update
void update(vpMomentObject &object)
Definition: vpMoment.cpp:127

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

vpPoint::set_x
void set_x(double x)
Set the point x coordinate in the image plane.
Definition: vpPoint.cpp:464

vpPoint::set_y
void set_y(double y)
Set the point y coordinate in the image plane.
Definition: vpPoint.cpp:466

VISP_NAMESPACE_NAME
Definition: vpEigenConversion.h:44

Parameters

data_base : database of moment primitives.

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

Definition at line 114 of file vpMoment.cpp.

References vpMoment::name().

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

◆ name()

const std::string vpMomentCentered::name ( ) const

inlinevirtual

Moment name.

Implements vpMoment.

Definition at line 88 of file vpMomentCentered.h.

◆ printDependencies()

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

virtual

Prints moments required for calculation of vpMomentCentered, which are

Raw geometric moments (vpMomentObject) and
Centre of gravity (vpMomentGravityCentered)

Reimplemented from vpMoment.

Definition at line 137 of file vpMomentCentered.cpp.

References vpMomentDatabase::get(), vpMoment::getMoments(), vpMoment::getObject(), vpMomentGravityCenter::getXg(), vpMomentGravityCenter::getYg(), vpException::notInitialized, and vpMomentObject::printWithIndices().

◆ printWithIndices()

void vpMomentCentered::printWithIndices ( std::ostream & os ) const

Print in a readable form which looks better than output from << operator

Definition at line 119 of file vpMomentCentered.cpp.

References get(), vpMoment::getObject(), and vpMomentObject::getOrder().

◆ set()

BEGIN_VISP_NAMESPACE void vpMomentCentered::set	(	unsigned int	i,
		unsigned int	j,
		double	value
	)

protected

To set the values of centred moments. Required when normalizing the moment values.

Parameters

i	: first index of the 2D moment.
j	: second index of the 2D moment.
value	: value of the moment.

Definition at line 53 of file vpMomentCentered.cpp.

References vpException::badValue, vpMoment::getObject(), vpMomentObject::getOrder(), and 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.

Friends And Related Function Documentation

◆ operator<<

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

friend

Outputs the centered moment's values $\mu_{ij}$ to a stream presented as a matrix. The first line corresponds to $\mu_{0[0:order]}$ , the second one to $\mu_{1[0:order]}$ Values in table corresponding to a higher order are marked with an "x" and not computed.

For example, if the maximal order is 3, the following values are provided:

u00 u10 u20 u30
u01 u11 u21 x
u02 u12  x  x
u30 x    x  x

This output will be followed by an output with indexes as produced by printWithIndices() function

Definition at line 176 of file vpMomentCentered.cpp.

Member Data Documentation

◆ values

std::vector<double> vpMoment::values

protectedinherited

Definition at line 113 of file vpMoment.h.

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

Public Member Functions

Protected Member Functions

Protected Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

◆ vpMomentCentered()

Member Function Documentation

◆ compute()

◆ get() [1/2]

◆ get() [2/2]

◆ getMoments()

◆ getObject()

◆ linkTo()

◆ name()

◆ printDependencies()

◆ printWithIndices()

◆ set()

◆ update()

Friends And Related Function Documentation

◆ operator<<

Member Data Documentation

◆ values