#include <visp3/core/vpMomentCommon.h>

Inheritance diagram for vpMomentCommon:

Public Member Functions
	vpMomentCommon (double dstSurface, const std::vector< double > &ref, double refAlpha, double dstZ=1.0, bool flg_sxsyfromnormalized=false)

virtual	~vpMomentCommon () vp_override

void	updateAll (vpMomentObject &object) vp_override

Inherited functionalities from vpMomentDatabase
const vpMoment &	get (const std::string &moment_name, bool &found) const

vpMoment &	get_first ()

Static Public Member Functions
static double	getAlpha (vpMomentObject &object)

static std::vector< double >	getMu3 (vpMomentObject &object)

static double	getSurface (vpMomentObject &object)

Detailed Description

This class initializes and allows access to commonly used moments.

It is a vpMomentDatabase filled with the following moments:

There is no need to do the linkTo operations manually nor is it necessary to care about the order of moment computation.

This class carries an vpMomentCommon::updateAll() method capable of updating AND computing moments from an object (see 4-step process in vpMoment). The moments computed by this class are classical moments used in moment-based visual servoing. For more information see [46].

To initialize this moment set the user needs to compute the following things:

the Mu3 value set: set of third-order centered moments computed for a reference object. ( $\mu_{ij}$ with $i+j = 3$ ). These values allow the system to save the reference angular position and to perform planar rotations of more than 180 degrees if needed.
the destination depth.
the surface of the destination object in the end of the visual servoing process.
the reference alpha: angular position of the object used to obtain the Mu3 set.

Shortcuts for each of these prerequisites are provided by this class except depth (methods vpMomentCommon::getMu3(), vpMomentCommon::getSurface(), vpMomentCommon::getAlpha()).

Attention: Make sure your object is at least of order 5 when using this pre-filled database.

Examples: manServoMomentsSimple.cpp, servoMomentImage.cpp, servoMomentPoints.cpp, and servoMomentPolygon.cpp.

Definition at line 99 of file vpMomentCommon.h.

Constructor & Destructor Documentation

◆ vpMomentCommon()

vpMomentCommon::vpMomentCommon	(	double	dstSurface,
		const std::vector< double > &	ref,
		double	refAlpha,
		double	dstZ = `1.0`,
		bool	flg_sxsyfromnormalized = `false`
	)

Default constructor. Initializes the common database with the following moments: basic, gravity,centered,centered+normalized,normalized gravity,normalized surface, scale-plane-rotation-translation invariant, alpha, symmetric invariant.

Parameters

dstSurface	: destination surface. You may use vpMomentCommon::getSurface().
ref	: reference 3rd order moments (see vpMomentAlpha). You may use vpMomentCommon::getMu3().
refAlpha	: reference alpha (see vpMomentAlpha). You may use vpMomentCommon::getAlpha().
dstZ	: destination depth.
flg_sxsyfromnormalized	: flag to enable calculation of sx,sy from normalized moments.

Definition at line 54 of file vpMomentCommon.cpp.

References vpMoment::linkTo().

◆ ~vpMomentCommon()

vpMomentCommon::~vpMomentCommon ( )

virtual

Definition at line 225 of file vpMomentCommon.cpp.

Member Function Documentation

◆ get()

const vpMoment & vpMomentDatabase::get	(	const std::string &	moment_name,
		bool &	found
	)		const

inherited

Retrieves a moment from the database.

Parameters

moment_name	: Name of the moment's class.
found	: true if the moment's type exists in the database, false otherwise.

Returns: Moment corresponding to type.

Definition at line 64 of file vpMomentDatabase.cpp.

Referenced by vpMomentAlpha::compute(), vpMomentArea::compute(), vpMomentAreaNormalized::compute(), vpMomentCentered::compute(), vpMomentCInvariant::compute(), vpMomentGravityCenterNormalized::compute(), vpFeatureMomentAlpha::compute_interaction(), vpFeatureMomentArea::compute_interaction(), vpFeatureMomentAreaNormalized::compute_interaction(), vpFeatureMomentCentered::compute_interaction(), vpFeatureMomentCInvariant::compute_interaction(), vpFeatureMomentGravityCenter::compute_interaction(), vpFeatureMomentGravityCenterNormalized::compute_interaction(), vpMomentAlpha::printDependencies(), vpMomentArea::printDependencies(), vpMomentAreaNormalized::printDependencies(), vpMomentCentered::printDependencies(), vpMomentGravityCenterNormalized::printDependencies(), and vpFeatureMoment::update().

◆ get_first()

vpMoment& vpMomentDatabase::get_first ( )

inlineinherited

Get the first element in the database. May be useful in case an unnamed object is present but is the only element in the database.

Returns: the first element in the database.

Definition at line 153 of file vpMomentDatabase.h.

◆ getAlpha()

double vpMomentCommon::getAlpha ( vpMomentObject & object )

static

Gets a reference alpha of an object.

Parameters

object : Moment object.

Examples: manServoMomentsSimple.cpp, servoMomentImage.cpp, servoMomentPoints.cpp, and servoMomentPolygon.cpp.

Definition at line 175 of file vpMomentCommon.cpp.

References vpMomentAlpha::compute(), vpMomentCentered::compute(), vpMomentGravityCenter::compute(), vpMomentAlpha::get(), vpMoment::linkTo(), and vpMomentDatabase::updateAll().

◆ getMu3()

std::vector< double > vpMomentCommon::getMu3 ( vpMomentObject & object )

static

Gets the reference 3rd order moments of an object.

Parameters

object : Moment object.

Examples: manServoMomentsSimple.cpp, servoMomentImage.cpp, servoMomentPoints.cpp, and servoMomentPolygon.cpp.

Definition at line 198 of file vpMomentCommon.cpp.

References vpMomentCentered::compute(), vpMomentGravityCenter::compute(), vpMomentCentered::get(), vpMoment::linkTo(), and vpMomentDatabase::updateAll().

◆ getSurface()

double vpMomentCommon::getSurface ( vpMomentObject & object )

static

Gets the surface of an object

Parameters

object : moment object

Examples: manServoMomentsSimple.cpp, servoMomentImage.cpp, servoMomentPoints.cpp, and servoMomentPolygon.cpp.

Definition at line 148 of file vpMomentCommon.cpp.

References vpMomentCentered::compute(), vpMomentGravityCenter::compute(), vpMomentObject::DISCRETE, vpMomentCentered::get(), vpMoment::linkTo(), and vpMomentDatabase::updateAll().

◆ updateAll()

void vpMomentCommon::updateAll ( vpMomentObject & object )

virtual

Updates all moments in the database with the object and computes all their values. This is possible because this particular database knows the link between the moments it contains. The order of computation is as follows: vpMomentGravityCenter,vpMomentCentered,vpMomentAlpha,vpMomentCInvariant,vpMomentSInvariant,vpMomentAreaNormalized,vpMomentGravityCenterNormalized

Parameters

object : Moment object.

Example of using a preconfigured database to compute one of the C-invariants:

#include <iostream>
#include <visp3/core/vpMomentCInvariant.h>
#include <visp3/core/vpMomentCommon.h>
#include <visp3/core/vpMomentObject.h>
#include <visp3/core/vpPoint.h>
 
int main()
{
  // Define two discrete points
  vpPoint p;
  std::vector<vpPoint> vec_p; // std::vector that contains the vertices of the contour polygon
 
  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)
  vec_p.push_back(p);
  p.set_x(-3);
  p.set_y(0); // coordinates in meters in the image plane (vertex 3)
  vec_p.push_back(p);
  p.set_x(-3);
  p.set_y(1); // coordinates in meters in the image plane (vertex 4)
  vec_p.push_back(p);
 
  vpMomentObject obj(5); // Object initialized up to order 5 to handle
                        // all computations required by vpMomentCInvariant
  obj.setType(vpMomentObject::DENSE_POLYGON); // object is the inner part of a polygon
  obj.fromstd::vector(vec_p); // Init the discrete object with two points
 
  //initialisation with default values
  vpMomentCommon db(vpMomentCommon::getSurface(obj),vpMomentCommon::getMu3(obj),vpMomentCommon::getAlpha(obj),1.);
  bool success;
 
  db.updateAll(obj); // Update AND compute all moments
 
  //get C-invariant
  vpMomentCInvariant& C = static_cast<vpMomentCInvariant&>(db.get("vpMomentCInvariant",success));
  if(success) {
    std::cout << C.get(0) << std:: std::endl;
  } else
    std::cout << "vpMomentCInvariant not found." << std::endl;
 
  return 0;
}

Reimplemented from vpMomentDatabase.

Definition at line 125 of file vpMomentCommon.cpp.

References vpMomentAlpha::compute(), vpMomentArea::compute(), vpMomentAreaNormalized::compute(), vpMomentCentered::compute(), vpMomentCInvariant::compute(), vpMomentGravityCenter::compute(), vpMomentGravityCenterNormalized::compute(), vpException::getStringMessage(), and vpMomentDatabase::updateAll().

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ vpMomentCommon()

◆ ~vpMomentCommon()

Member Function Documentation

◆ get()

◆ get_first()

◆ getAlpha()

◆ getMu3()

◆ getSurface()

◆ updateAll()