Visual Servoing Platform  version 3.6.0 under development (2023-09-25)
vpMomentArea Class Reference

#include <visp3/core/vpMomentArea.h>

+ Inheritance diagram for vpMomentArea:

Public Member Functions

 vpMomentArea ()
virtual ~vpMomentArea ()
Inherited functionalities from vpMoment
const vpMomentObjectgetObject () const
const std::vector< double > & get () const
void linkTo (vpMomentDatabase &moments)
void update (vpMomentObject &object)

Protected Member Functions

vpMomentDatabasegetMoments () const

Protected Attributes

std::vector< double > values

Inherited functionalities from vpMomentArea

void compute ()
const char * name () const
void printDependencies (std::ostream &os) const
VISP_EXPORT std::ostream & operator<< (std::ostream &os, const vpMomentArea &m)

Detailed Description

Class handling the surface moment.

For a dense planar object, the area corresponds to the zero-order moment:

\[ a = m_{00} = \mu_{00} \]

When considering a discrete set of points, the moment $ m_{00} $ simply corresponds to the number of points. Since this is of no use in a servoing scheme, this class uses in this case $ a = \mu_{20} + \mu_{02} $, which is invariant to planar translation and rotation.

Definition at line 57 of file vpMomentArea.h.

Constructor & Destructor Documentation

◆ vpMomentArea()

vpMomentArea::vpMomentArea ( )

Default constructor.

Definition at line 73 of file vpMomentArea.cpp.

References vpMoment::values.

◆ ~vpMomentArea()

virtual vpMomentArea::~vpMomentArea ( )

Definition at line 61 of file vpMomentArea.h.

Member Function Documentation

◆ compute()

void vpMomentArea::compute ( )

Has the area $ a = m_{00} = \mu_{00} $ for dense objects, $ \mu_{20}+\mu_{02} $ for a discrete set of points. Gets the value of $ m_{00} $ from vpMomentCentered.

Implements vpMoment.

Definition at line 49 of file vpMomentArea.cpp.

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

Referenced by vpMomentCommon::updateAll().

◆ get()

◆ getMoments()

◆ getObject()

◆ linkTo()

void vpMoment::linkTo ( vpMomentDatabase data_base)

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.

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()
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)
obj.setType(vpMomentObject::DISCRETE); // Discrete mode.
obj.fromVector(vec_p); // Init the dense object with the polygon
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;
This class defines the double-indexed centered moment descriptor .
This class allows to register all vpMoments so they can access each other according to their dependen...
Class describing 2D gravity center moment.
Class for generic objects.
void linkTo(vpMomentDatabase &moments)
Definition: vpMoment.cpp:98
void update(vpMomentObject &object)
Definition: vpMoment.cpp:115
Class that defines a 3D point in the object frame and allows forward projection of a 3D point in the ...
Definition: vpPoint.h:77
void set_x(double x)
Set the point x coordinate in the image plane.
Definition: vpPoint.cpp:508
void set_y(double y)
Set the point y coordinate in the image plane.
Definition: vpPoint.cpp:510
data_base: database of moment primitives.
mbot-apriltag-ibvs.cpp, servoBebop2.cpp, servoPixhawkDroneIBVS.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* vpMomentArea::name ( ) const

Moment name.

Implements vpMoment.

Definition at line 67 of file vpMomentArea.h.

◆ printDependencies()

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

If the vpMomentObject type is

  1. DISCRETE(set of discrete points), uses mu20+mu02
  2. DENSE_FULL_OBJECT(from image) used mu00

Reimplemented from vpMoment.

Definition at line 90 of file vpMomentArea.cpp.

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

◆ update()

void vpMoment::update ( vpMomentObject moment_object)

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

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 vpMomentArea m 

Outputs the moment's values to a stream.

Definition at line 78 of file vpMomentArea.cpp.

Member Data Documentation

◆ values