#include <vpMomentGravityCenter.h>

Inheritance diagram for vpMomentGravityCenter:

Public Member Functions
	vpMomentGravityCenter ()

void	compute ()

std::vector< double > &	get ()

double	getXg () const

double	getYg () const

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, 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 $x_g$ and $y_g$ .

These coordinates are defined as follows: $x_g = \frac{m_{01}}{m_{00}}$ , $y_g = \frac{m_{10}}{m_{00}}$

#include <visp/vpMomentObject.h>
#include <visp/vpPoint.h>
#include <visp/vpMomentGravityCenter.h>
#include <iostream>
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

Definition at line 113 of file vpMomentGravityCenter.h.

Constructor & Destructor Documentation

vpMomentGravityCenter::vpMomentGravityCenter ( )

Default constructor.

Definition at line 55 of file vpMomentGravityCenter.cpp.

References vpMoment::values.

Member Function Documentation

void vpMomentGravityCenter::compute ( )

virtual

Computes the two gravity center coordinates commonly called $x_g$ and $y_g$ .

Implements vpMoment.

Reimplemented in vpMomentGravityCenterNormalized.

Definition at line 47 of file vpMomentGravityCenter.cpp.

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

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

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

Returns a vector of the two gravity center coordinates.

Returns: Coordinates in the following moment: .

Definition at line 63 of file vpMomentGravityCenter.cpp.

References vpMoment::values.

Referenced by vpMomentGravityCenterNormalized::compute(), and vpMomentCentered::compute().

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(), vpMomentCentered::compute(), vpMomentAreaNormalized::compute(), vpMomentCInvariant::compute(), and vpMomentAlpha::compute().

vpMomentObject& vpMoment::getObject ( ) const

inlineinherited

Definition at line 119 of file vpMoment.h.

double vpMomentGravityCenter::getXg ( ) const

inline

Shortcut function to retrieve $x_g$ .

Returns: The first gravity center coordinate.

Definition at line 123 of file vpMomentGravityCenter.h.

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

double vpMomentGravityCenter::getYg ( ) const

inline

Shortcut function to retrieve $y_g$ .

Returns: The second gravity center coordinate.

Definition at line 128 of file vpMomentGravityCenter.h.

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

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* vpMomentGravityCenter::name ( )

inlinevirtual

The class's string name.

Implements vpMoment.

Reimplemented in vpMomentGravityCenterNormalized.

Definition at line 132 of file vpMomentGravityCenter.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,
		const vpMomentGravityCenter &	v
	)

friend

Outputs the moment's values to a stream.

Definition at line 70 of file vpMomentGravityCenter.cpp.

Member Data Documentation

std::vector<double> vpMoment::values

protectedinherited

Definition at line 110 of file vpMoment.h.

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