#include <vpMomentCommon.h>

Inheritance diagram for vpMomentCommon:

Public Member Functions
	vpMomentCommon (double dstSurface, std::vector< double > ref, double refAlpha, double dstZ=1.0)

void	updateAll (vpMomentObject &object)

vpMoment &	get (const char *type, bool &found)

vpMoment &	get_first ()

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

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 [12].

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 96 of file vpMomentCommon.h.

Constructor & Destructor Documentation

vpMomentCommon::vpMomentCommon	(	double	dstSurface,
		std::vector< double >	ref,
		double	refAlpha,
		double	dstZ = `1.0`
	)

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.

Definition at line 53 of file vpMomentCommon.cpp.

References vpMoment::linkTo().

Member Function Documentation

vpMoment & vpMomentDatabase::get	(	const char *	type,
		bool &	found
	)

inherited

Retrieves a moment from the database.

Parameters

type	: 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 65 of file vpMomentDatabase.cpp.

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

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 147 of file vpMomentDatabase.h.

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

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 194 of file vpMomentCommon.cpp.

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

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 150 of file vpMomentCommon.cpp.

References vpMomentCentered::compute(), vpMomentGravityCenter::compute(), vpMomentObject::DISCRETE, vpMomentCentered::get(), vpMoment::linkTo(), and vpMomentDatabase::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 <visp/vpMomentObject.h>
#include <visp/vpPoint.h>
#include <visp/vpMomentCInvariant.h>
#include <visp/vpMomentCommon.h>
#include <iostream>
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.

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

Definition at line 126 of file vpMomentCommon.cpp.

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

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation