Visual Servoing Platform  version 3.3.0
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vpMomentBasic Class Reference
core: Core module » Tools » Image moments

#include <vpMomentBasic.h>

+ Inheritance diagram for vpMomentBasic:

Public Member Functions

 vpMomentBasic ()
 
virtual ~vpMomentBasic ()
 
void compute ()
 
const std::vector< double > & get () const
 
double get (unsigned int i, unsigned int j) const
 
const char * name () 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

vpMomentDatabase & getMoments () const
 

Protected Attributes

std::vector< double > values
 

Friends

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

Detailed Description

This class defines the 2D basic moment $m_{ij}$. This class is a wrapper for vpMomentObject wich allows to use it as a moment. This enables all common operations such as adding to a vpMomentDatabase.

In the case of a dense object O, 2D basic moments are defined by:

\[m_{ij} = \int \int_{O} x^j y^j dx dy\]

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

\[m_{ij} = \sum_{k=1}^{n} x_k^j y_k^j \]

The selection of a dense or discrete object is done in vpMomentObject. The maximum order of vpMomentBasic is the same as that of vpMomentObject (ie: $i+j \leq $ vpMomentObject::getOrder).

Note that in the continuous case, the basic moment $m_{00}$ corresponds to the surface $a$ of the object. In the discrete case, it is the number of discrete points $n$.

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

Definition at line 73 of file vpMomentBasic.h.

Constructor & Destructor Documentation

◆ vpMomentBasic()

vpMomentBasic::vpMomentBasic ( )

Default constructor.

Definition at line 43 of file vpMomentBasic.cpp.

◆ ~vpMomentBasic()

virtual vpMomentBasic::~vpMomentBasic ( )
inlinevirtual

Definition at line 77 of file vpMomentBasic.h.

Member Function Documentation

◆ compute()

void vpMomentBasic::compute ( )
virtual

Dummy function. Everything is already done in object.

Implements vpMoment.

Definition at line 66 of file vpMomentBasic.cpp.

◆ get() [1/2]

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

Retrieve all moments of all orders computed. vpMomentBasic::get()[j*order+i] refers to moment $m_{ij}$.

Returns
all computed moments.

Same behaviour as vpMomentObject.

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

Definition at line 51 of file vpMomentBasic.cpp.

◆ get() [2/2]

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

Gets the desired moment using indexes.

Parameters
i: first index of the 2D moment.
j: second index of the 2D moment.
Returns
$m_{ij}$ moment.

Same behaviour as vpMomentObject.

Definition at line 61 of file vpMomentBasic.cpp.

◆ getMoments()

vpMomentDatabase& vpMoment::getMoments ( ) const
inlineprotectedinherited

Returns the linked moment database.

Returns
the moment database

Definition at line 122 of file vpMoment.h.

◆ getObject()

const vpMomentObject& vpMoment::getObject ( ) const
inlineinherited

Definition at line 149 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 97 of file vpMoment.cpp.

◆ name()

const char* vpMomentBasic::name ( ) const
inlinevirtual

Moment name.

Implements vpMoment.

Definition at line 85 of file vpMomentBasic.h.

◆ printDependencies()

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

No dependencies on other vpMoments, since basic moments are computed in vpMomentObject Just prints the basic moments in vpMomentObject with indices

Reimplemented from vpMoment.

Definition at line 83 of file vpMomentBasic.cpp.

◆ 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 114 of file vpMoment.cpp.

Friends And Related Function Documentation

◆ operator<<

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

Outputs the moment's values to a stream. Same output as in vpMomentObject.

Definition at line 72 of file vpMomentBasic.cpp.

Member Data Documentation

◆ values

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

Definition at line 117 of file vpMoment.h.

vpMoment::linkTo
void linkTo(vpMomentDatabase &moments)
Definition: vpMoment.cpp:97
vpMomentCentered
This class defines the double-indexed centered moment descriptor .
Definition: vpMomentCentered.h:78
vpMomentGravityCenter::compute
void compute()
Definition: vpMomentGravityCenter.cpp:44
vpMomentDatabase
This class allows to register all vpMoments so they can access each other according to their dependen...
Definition: vpMomentDatabase.h:130
vpMomentObject::DISCRETE
Definition: vpMomentObject.h:230
vpMoment::update
void update(vpMomentObject &object)
Definition: vpMoment.cpp:114
vpPoint::set_y
void set_y(double y)
Set the point y coordinate in the image plane.
Definition: vpPoint.cpp:473
vpMomentObject
Class for generic objects.
Definition: vpMomentObject.h:218
vpMomentCentered::compute
void compute()
Definition: vpMomentCentered.cpp:64
vpPoint
Class that defines what is a point.
Definition: vpPoint.h:57
vpPoint::set_x
void set_x(double x)
Set the point x coordinate in the image plane.
Definition: vpPoint.cpp:471
vpMomentGravityCenter
Class describing 2D gravity center moment.
Definition: vpMomentGravityCenter.h:112