vpMomentGravityCenter Class Reference

#include <vpMomentGravityCenter.h>

Inheritance diagram for vpMomentGravityCenter:

Public Member Functions
	vpMomentGravityCenter ()
virtual	~vpMomentGravityCenter ()
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

Inherited functionalities from vpMomentGravityCenter
void	compute ()
const std::vector< double > &	get () const
double	getXg () const
double	getYg () const
const char *	name () const
void	printDependencies (std::ostream &os) const
VISP_EXPORT std::ostream &	operator<< (std::ostream &os, const vpMomentGravityCenter &v)

Detailed Description

Class describing 2D gravity center moment.

This moment can be computed from scratch (no need to compute any different moments before computing this). It gives access to both coordinates of the gravity center and .

These coordinates are defined as follows: ,

#include <iostream>
#include <visp3/core/vpMomentGravityCenter.h>
#include <visp3/core/vpMomentObject.h>
#include <visp3/core/vpPoint.h>
 
int main()
{
  // Define the contour of an object by a 5 clockwise vertices on a plane
  vpPoint p;
  std::vector<vpPoint> vec_p; // vector that contains the vertices of the contour polygon
 
  p.set_x(-0.2); p.set_y(0.1); // coordinates in meters in the image plane (vertex 1)
  vec_p.push_back(p);
  p.set_x(+0.3); p.set_y(0.1); // coordinates in meters in the image plane (vertex 2)
  vec_p.push_back(p);
  p.set_x(+0.2); p.set_y(-0.1); // coordinates in meters in the image plane (vertex 3)
  vec_p.push_back(p);
  p.set_x(-0.2); p.set_y(-0.15); // coordinates in meters in the image plane (vertex 4)
  vec_p.push_back(p);
  p.set_x(-0.2); p.set_y(0.1); // close the contour (vertex 5 = vertex 1)
  vec_p.push_back(p);
 
  vpMomentObject obj(1); // Create an image moment object with 1 as
                         // maximum order (because only m00,m01,m10
                         // are needed to compute the gravity center primitive.
  obj.setType(vpMomentObject::DENSE_POLYGON); // The object is defined by a countour polygon
  obj.fromVector(vec_p); // Init the dense object with the polygon
 
  vpMomentGravityCenter g; // declaration of gravity center
  g.update(obj); // specify the object
  g.compute(); // compute the moment
 
  std::cout << "Xg=" << g.getXg() << std::endl; // access to Xg
  std::cout << "Yg=" << g.getYg() << std::endl; // access to Yg
 
  std::cout << g << std:: endl; // print gravity center
 
  return 0;
}

This example produces the following results:

Xg=0.0166667
Yg=-0.00833333
Xg=0.0166667, Yg=-0.00833333

Examples

mbot-apriltag-ibvs.cpp, servoBebop2.cpp, servoPixhawkDroneIBVS.cpp, and testMomentAlpha.cpp.

Definition at line 108 of file vpMomentGravityCenter.h.

Constructor & Destructor Documentation

vpMomentGravityCenter()

vpMomentGravityCenter::vpMomentGravityCenter

(

)

Default constructor.

Definition at line 54 of file vpMomentGravityCenter.cpp.

References vpMoment::values, and vpMoment::vpMoment().

Referenced by vpMomentGravityCenterNormalized::compute(), operator<<, vpMomentGravityCenterNormalized::printDependencies(), and vpMomentGravityCenterNormalized::vpMomentGravityCenterNormalized().

~vpMomentGravityCenter()

virtual vpMomentGravityCenter::~vpMomentGravityCenter ( )

inlinevirtual

Definition at line 112 of file vpMomentGravityCenter.h.

Member Function Documentation

compute()

void vpMomentGravityCenter::compute ( )

virtual

Computes the two gravity center coordinates commonly called and .

Implements vpMoment.

Reimplemented in vpMomentGravityCenterNormalized.

Examples

mbot-apriltag-ibvs.cpp, servoBebop2.cpp, servoPixhawkDroneIBVS.cpp, and testMomentAlpha.cpp.

Definition at line 45 of file vpMomentGravityCenter.cpp.

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

get()

const std::vector< double > & vpMomentGravityCenter::get

(

)

const

Returns a vector of the two gravity center coordinates.

Returns

Coordinates in the following moment: .

Definition at line 60 of file vpMomentGravityCenter.cpp.

References vpMoment::values.

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

getObject()

const vpMomentObject & vpMoment::getObject ( ) const

inlineinherited

Definition at line 145 of file vpMoment.h.

Referenced by vpMomentArea::compute(), vpMomentAreaNormalized::compute(), vpMomentCentered::compute(), vpMomentCInvariant::compute(), vpMomentGravityCenter::compute(), vpMomentBasic::get(), vpMomentBasic::get(), vpMomentCentered::get(), vpMomentBasic::operator<<, vpMomentCentered::operator<<, vpMomentArea::printDependencies(), vpMomentAreaNormalized::printDependencies(), vpMomentBasic::printDependencies(), vpMomentCentered::printDependencies(), vpMomentGravityCenter::printDependencies(), vpMomentCentered::printWithIndices(), and vpMomentCentered::set().

getXg()

double vpMomentGravityCenter::getXg ( ) const

inline

Shortcut function to retrieve .

Returns

The first gravity center coordinate.

Definition at line 122 of file vpMomentGravityCenter.h.

References vpMoment::values.

Referenced by vpFeatureMomentAlpha::compute_interaction(), vpFeatureMomentArea::compute_interaction(), vpFeatureMomentAreaNormalized::compute_interaction(), vpFeatureMomentCentered::compute_interaction(), vpFeatureMomentGravityCenter::compute_interaction(), vpFeatureMomentGravityCenterNormalized::compute_interaction(), and vpMomentCentered::printDependencies().

getYg()

double vpMomentGravityCenter::getYg ( ) const

inline

Shortcut function to retrieve .

Returns

The second gravity center coordinate.

Definition at line 127 of file vpMomentGravityCenter.h.

References vpMoment::values.

Referenced by vpFeatureMomentAlpha::compute_interaction(), vpFeatureMomentArea::compute_interaction(), vpFeatureMomentAreaNormalized::compute_interaction(), vpFeatureMomentCentered::compute_interaction(), vpFeatureMomentGravityCenter::compute_interaction(), vpFeatureMomentGravityCenterNormalized::compute_interaction(), and vpMomentCentered::printDependencies().

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, servoPixhawkDroneIBVS.cpp, and testMomentAlpha.cpp.

Definition at line 98 of file vpMoment.cpp.

References vpException::memoryAllocationError, and name().

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

name()

const char * vpMomentGravityCenter::name ( ) const

inlinevirtual

The class's string name.

Implements vpMoment.

Reimplemented in vpMomentGravityCenterNormalized.

Definition at line 131 of file vpMomentGravityCenter.h.

printDependencies()

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

virtual

Prints its dependencies Basic moments m10, m01 and m00 from vpMomentObject

Reimplemented from vpMoment.

Reimplemented in vpMomentGravityCenterNormalized.

Definition at line 76 of file vpMomentGravityCenter.cpp.

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

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.

Referenced by name().

Friends And Related Symbol Documentation

operator<<

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

friend

Outputs the moment's values to a stream.

Definition at line 65 of file vpMomentGravityCenter.cpp.

References operator<<, vpMoment::values, and vpMomentGravityCenter().

Referenced by operator<<.

Member Data Documentation

values

std::vector<double> vpMoment::values

protectedinherited

Definition at line 113 of file vpMoment.h.

Referenced by vpMomentCInvariant::C1(), vpMomentCInvariant::C10(), vpMomentCInvariant::C2(), vpMomentCInvariant::C3(), vpMomentCInvariant::C4(), vpMomentCInvariant::C5(), vpMomentCInvariant::C6(), vpMomentCInvariant::C7(), vpMomentCInvariant::C8(), vpMomentCInvariant::C9(), vpMomentAlpha::compute(), vpMomentArea::compute(), vpMomentAreaNormalized::compute(), vpMomentCentered::compute(), vpMomentCInvariant::compute(), vpMomentGravityCenter::compute(), vpMomentGravityCenterNormalized::compute(), get(), vpMomentAlpha::get(), vpMomentCentered::get(), vpMomentCInvariant::get(), vpMomentGravityCenter::get(), vpMomentCInvariant::getMomentVector(), vpMomentGravityCenter::getXg(), vpMomentGravityCenter::getYg(), operator<<, vpMomentAlpha::operator<<, vpMomentArea::operator<<, vpMomentAreaNormalized::operator<<, vpMomentCentered::operator<<, vpMomentGravityCenter::operator<<, vpMomentGravityCenterNormalized::operator<<, vpMomentCInvariant::Px(), vpMomentCInvariant::Py(), vpMomentCentered::set(), vpMomentCInvariant::Sx(), vpMomentCInvariant::Sy(), vpMoment(), vpMomentAlpha::vpMomentAlpha(), vpMomentArea::vpMomentArea(), vpMomentAreaNormalized::vpMomentAreaNormalized(), vpMomentCInvariant::vpMomentCInvariant(), and vpMomentGravityCenter::vpMomentGravityCenter().