#include <vpMomentCentered.h>

Inheritance diagram for vpMomentCentered:

Public Member Functions
	vpMomentCentered ()

void	compute ()

double	get (unsigned int i, unsigned int j)

std::vector< double > &	get ()

const char *	name ()

vpMomentObject &	getObject () const

void	linkTo (vpMomentDatabase &moments)

void	update (vpMomentObject &object)

Protected Member Functions
vpMomentDatabase &	getMoments ()

Protected Attributes
std::vector< double >	values

Friends
VISP_EXPORT std::ostream &	operator<< (std::ostream &os, 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.

Definition at line 79 of file vpMomentCentered.h.

Constructor & Destructor Documentation

vpMomentCentered::vpMomentCentered ( )

Default constructor.

Definition at line 80 of file vpMomentCentered.cpp.

Member Function Documentation

void vpMomentCentered::compute ( )

virtual

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

Implements vpMoment.

Definition at line 52 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().

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

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.

Definition at line 90 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(), vpFeatureMomentCInvariant::compute_interaction(), vpFeatureMomentGravityCenter::compute_interaction(), vpFeatureMomentGravityCenterNormalized::compute_interaction(), vpMomentCommon::getMu3(), and vpMomentCommon::getSurface().

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

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 123 of file vpMomentCentered.h.

References vpMoment::get().

vpMomentDatabase& vpMoment::getMoments ( )

inlineprotectedinherited

Returns the linked moment database.

Returns: the moment database

Definition at line 115 of file vpMoment.h.

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

vpMomentObject& vpMoment::getObject ( ) const

inlineinherited

Definition at line 119 of file vpMoment.h.

void vpMoment::linkTo ( vpMomentDatabase & moments )

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 <visp/vpMomentObject.h>

#include <visp/vpPoint.h>

#include <visp/vpMomentGravityCenter.h>

#include <visp/vpMomentDatabase.h>

#include <visp/vpMomentCentered.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 containts 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

moments : database of moment primitives.

Definition at line 104 of file vpMoment.cpp.

References vpMoment::name().

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

const char* vpMomentCentered::name ( )

inlinevirtual

Moment name.

Implements vpMoment.

Definition at line 91 of file vpMomentCentered.h.

void vpMoment::update ( vpMomentObject & object )

inherited

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

Parameters

object : object descriptor of the current camera vision.

Definition at line 117 of file vpMoment.cpp.

Friends And Related Function Documentation

VISP_EXPORT std::ostream& operator<<	(	std::ostream &	os,
		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

Definition at line 112 of file vpMomentCentered.cpp.

Member Data Documentation

std::vector<double> vpMoment::values

protectedinherited

Definition at line 110 of file vpMoment.h.

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

Member Function Documentation

Friends And Related Function Documentation

Member Data Documentation