#include <visp3/core/vpMomentCentered.h>

Inheritance diagram for vpMomentCentered:

Public Member Functions
	vpMomentCentered ()

virtual	~vpMomentCentered ()

void	compute ()

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

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

const char *	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 79 of file vpMomentCentered.h.

Constructor & Destructor Documentation

◆ vpMomentCentered()

vpMomentCentered::vpMomentCentered ( )

Default constructor.

Definition at line 95 of file vpMomentCentered.cpp.

◆ ~vpMomentCentered()

virtual vpMomentCentered::~vpMomentCentered ( )

inlinevirtual

Definition at line 83 of file vpMomentCentered.h.

References vpMoment::compute().

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 65 of file vpMomentCentered.cpp.

References vpMath::comb(), vpMomentGravityCenter::get(), vpMomentDatabase::get(), vpMomentObject::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]

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 103 of file vpMomentCentered.cpp.

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

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

◆ get() [2/2]

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 135 of file vpMomentCentered.h.

References vpMoment::get().

◆ getMoments()

vpMomentDatabase& vpMoment::getMoments ( ) const

inlineprotectedinherited

Returns the linked moment database.

Returns: the moment database

Definition at line 123 of file vpMoment.h.

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

◆ getObject()

const vpMomentObject& vpMoment::getObject ( ) const

inlineinherited

Definition at line 150 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>
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)
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;
}

Parameters

data_base : database of moment primitives.

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

Definition at line 98 of file vpMoment.cpp.

References vpException::memoryAllocationError, and vpMoment::name().

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

◆ name()

const char* vpMomentCentered::name ( ) const

inlinevirtual

Moment name.

Implements vpMoment.

Definition at line 92 of file vpMomentCentered.h.

References vpMoment::operator<<, and vpMoment::printDependencies().

◆ 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 172 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 154 of file vpMomentCentered.cpp.

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

◆ set()

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 52 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 115 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 133 of file vpMomentCentered.cpp.

Member Data Documentation

◆ values

std::vector<double> vpMoment::values

protectedinherited

Definition at line 118 of file vpMoment.h.

Referenced by vpMomentArea::compute(), vpMomentGravityCenterNormalized::compute(), compute(), vpMomentGravityCenter::compute(), vpMomentAreaNormalized::compute(), vpMomentCInvariant::compute(), vpMomentAlpha::compute(), get(), vpMomentGravityCenter::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()

◆ ~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