#include <vpMomentAreaNormalized.h>

Inheritance diagram for vpMomentAreaNormalized:

Public Member Functions
	vpMomentAreaNormalized (double desiredSurface, double desiredDepth)

void	compute ()

double	getDesiredDepth () const

double	getDesiredSurface () const

const char *	name () const

const vpMomentObject &	getObject () const

const std::vector< double > &	get () 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 vpMomentAreaNormalized &v)

Detailed Description

Class handling the normalized surface moment that is invariant in scale and used to estimate depth.

This moment depends on vpMomentCentered.

The idea behind vpMomentAreaNormalized is described in [23].

During a visual servoing process, a vpMomentAreaNormalized will converge towards the desired depth when the current surface will converge to the destination surface. It is defined as follows: $a_n=Z^* \sqrt{\frac{a^*}{a}}$ where a is the current surface and a* the destination surface. Consequently, the vpMomentAreaNormalized needs to have information about the desired depth Z* and the desired surface a*.

Warning

About the order of the object. The surface (refered to as a in the above paragraph) depends of the nature of the object.

In case of a continuous object (when vpMomentObject::getType() is vpMomentObject::DENSE_FULL_OBJECT or vpMomentObject::DENSE_POLYGON) $a=m_{00}$ .
In case of a discrete object (when vpMomentObject::getType() is vpMomentObject::DISCRETE) $a=\mu_{20}+\mu_{02}$ .

Therefore, a vpMomentObject has to be of minimum order 2 in order to compute a vpMomentAreaNormalized moment in the discrete case and of minimum order 0 in continous cases.

This example shows a computation in the discrete case.

#include <visp/vpMomentObject.h>
#include <visp/vpPoint.h>
#include <visp/vpMomentGravityCenter.h>
#include <visp/vpMomentDatabase.h>
#include <visp/vpMomentCentered.h>
#include <visp/vpMomentAreaNormalized.h>
int main()
{
  vpPoint p;
  std::vector<vpPoint> vec_p; // vector that contains object points
  p.set_x(1); p.set_y(1); // coordinates in meters in the image plane of point 1
  vec_p.push_back(p);
  p.set_x(2); p.set_y(2); // coordinates in meters in the image plane of point 2
  vec_p.push_back(p);
  vpMomentObject obj(2); // Object where all the moment defined with
                         // i+j <= 2 will be computed below. Order is
                         // 2 because in discrete mode, the surface
                         // computation is a=mu02+mu02
  obj.setType(vpMomentObject::DISCRETE); // Discrete mode for object
  obj.fromVector(vec_p); // initialize the object with the points coordinates
  vpMomentDatabase db; //reference database
  vpMomentGravityCenter g; // declaration of gravity center
  vpMomentCentered mc; //  centered moments
  vpMomentAreaNormalized an(2,1); //declare normalized surface with
                                //destination depth of 1 meter and
                                //destination surface of 2 m2
  g.linkTo(db); //add gravity center to database
  mc.linkTo(db); //add centered moments
  an.linkTo(db); //add alpha depending on centered moments
  db.updateAll(obj); // All of the moments must be updated, not just an
  g.compute(); // compute the moment
  mc.compute(); //compute centered moments AFTER gravity center
  an.compute(); //compute alpha AFTER centered moments.
  std::cout << an << std::endl;
  return 0;
}

This code produces the following output:

An:1.41421

Definition at line 132 of file vpMomentAreaNormalized.h.

Constructor & Destructor Documentation

vpMomentAreaNormalized::vpMomentAreaNormalized	(	double	desired_surface,
		double	desired_depth
	)

Default constructor.

Parameters

desired_surface	: desired area a* when the visual servoing converges.
desired_depth	: desired depth Z* when the visual servoing converges.

Definition at line 77 of file vpMomentAreaNormalized.cpp.

References vpMoment::values.

Member Function Documentation

void vpMomentAreaNormalized::compute ( )

virtual

Computes the normalized area $a_n=Z^* \sqrt{\frac{a^*}{a}}$ . Depends on vpMomentCentered.

Implements vpMoment.

Definition at line 52 of file vpMomentAreaNormalized.cpp.

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

Referenced by vpMomentCommon::updateAll().

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

inlineinherited

Returns all values computed by the moment.

Returns: vector of values

Definition at line 129 of file vpMoment.h.

Referenced by vpMomentGravityCenterNormalized::compute(), vpFeatureMomentArea::compute_interaction(), vpFeatureMomentAreaNormalized::compute_interaction(), vpFeatureMomentGravityCenterNormalized::compute_interaction(), vpMomentCentered::get(), vpFeatureMoment::init(), and vpFeatureMoment::update().

double vpMomentAreaNormalized::getDesiredDepth ( ) const

inline

Retrieves the desired depth Z* as specified in the constructor.

Definition at line 142 of file vpMomentAreaNormalized.h.

double vpMomentAreaNormalized::getDesiredSurface ( ) const

inline

Retrieves the desired surface a* as specified in the constructor.

Definition at line 146 of file vpMomentAreaNormalized.h.

vpMomentDatabase& vpMoment::getMoments ( )

inlineprotectedinherited

Returns the linked moment database.

Returns: the moment database

Definition at line 119 of file vpMoment.h.

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

const vpMomentObject& vpMoment::getObject ( ) const

inlineinherited

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 <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

data_base : database of moment primitives.

Definition at line 103 of file vpMoment.cpp.

References vpException::memoryAllocationError, and vpMoment::name().

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

const char* vpMomentAreaNormalized::name ( ) const

inlinevirtual

Moment name.

Implements vpMoment.

Definition at line 151 of file vpMomentAreaNormalized.h.

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 120 of file vpMoment.cpp.

Friends And Related Function Documentation

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

friend

Outputs the moment's values to a stream.

Definition at line 86 of file vpMomentAreaNormalized.cpp.

Member Data Documentation

std::vector<double> vpMoment::values

protectedinherited

Definition at line 114 of file vpMoment.h.

Referenced by vpMomentArea::compute(), vpMomentGravityCenterNormalized::compute(), vpMomentCentered::compute(), vpMomentGravityCenter::compute(), compute(), vpMomentCInvariant::compute(), vpMomentAlpha::compute(), vpMomentCentered::get(), vpMomentGravityCenter::get(), vpMomentCInvariant::getMomentVector(), vpMomentCentered::set(), vpMomentAlpha::vpMomentAlpha(), vpMomentArea::vpMomentArea(), 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