vpMomentAlpha.h

/*
 * ViSP, open source Visual Servoing Platform software.
 * Copyright (C) 2005 - 2023 by Inria. All rights reserved.
 *
 * This software is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * See the file LICENSE.txt at the root directory of this source
 * distribution for additional information about the GNU GPL.
 *
 * For using ViSP with software that can not be combined with the GNU
 * GPL, please contact Inria about acquiring a ViSP Professional
 * Edition License.
 *
 * See https://visp.inria.fr for more information.
 *
 * This software was developed at:
 * Inria Rennes - Bretagne Atlantique
 * Campus Universitaire de Beaulieu
 * 35042 Rennes Cedex
 * France
 *
 * If you have questions regarding the use of this file, please contact
 * Inria at visp@inria.fr
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Description:
 * Alpha moment descriptor for in-plane orientation.
 */

 
#ifndef _vpMomentAlpha_h_
#define _vpMomentAlpha_h_
 
#include <visp3/core/vpMoment.h>

  vpMomentObject objRef(3);                      // Reference object. Must be of order 3 because we will
                                                 // need the 3rd order centered moments
 
  objRef.setType(vpMomentObject::DENSE_POLYGON); // Object is the inner part of a polygon
  objRef.fromVector(vec_p);                      // Init the dense object with the polygon
 
  vpMomentDatabase dbRef;                        // Reference database
  vpMomentGravityCenter gRef;                    // Declaration of gravity center
  vpMomentCentered mcRef;                        // Centered moments
  vpMomentAlpha alphaRef;                        // Declare alpha as reference
 
  gRef.linkTo(dbRef);                            // Add gravity center to database
  mcRef.linkTo(dbRef);                           // Add centered moments
  alphaRef.linkTo(dbRef);                        // Add alpha depending on centered moments
 
  dbRef.updateAll(objRef);                       // All of the moments must be updated, not just alpha
 
  gRef.compute();                                // Compute the moment
  mcRef.compute();                               // Compute centered moments AFTER gravity center
  alphaRef.compute();                            // Compute alpha AFTER centered moments.
 
  // The order of values in the vector must be as follows: mu30 mu21 mu12 mu03
  std::vector<double> mu3ref = {mcRef.get(3,0), mcRef.get(2,1), mcRef.get(1,2), mcRef.get(0,3)};
 
  std::cout << "--- Reference object ---" << std::endl;
  std::cout << "alphaRef=" << vpMath::deg(alphaRef.get()) << " deg" << std::endl << "mu3="; // print reference alpha
  std::for_each (mu3ref.begin(), mu3ref.end(), print);
  std::cout << std::endl;

  vec_p.clear();
 
  p.set_x(-3); p.set_y(1);                       // Coordinates in meters in the image plane (vertex 4)
  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(2); p.set_y(-2);                       // Coordinates in meters in the image plane (vertex 2)
  vec_p.push_back(p);
  p.set_x(1); p.set_y(-1);                       // Coordinates in meters in the image plane (vertex 1)
  vec_p.push_back(p);
 
  vpMomentObject obj(3);                         // Second object. Order 3 is also required because of the Alpha
                                                 // will compare third-order centered moments to given reference.
 
  obj.setType(vpMomentObject::DENSE_POLYGON);    // Object is the inner part of a polygon
  obj.fromVector(vec_p);                         // Init the dense object with the polygon
 
  vpMomentDatabase db;                           // Database
  vpMomentGravityCenter g;                       // Declaration of gravity center
  vpMomentCentered mc;                           // mc contains centered moments
  vpMomentAlpha alpha(mu3ref, alphaRef.get());   // Declare alpha as relative to a reference
 
  g.linkTo(db);                                  // Add gravity center to database
  mc.linkTo(db);                                 // Add centered moments
  alpha.linkTo(db);                              // Add alpha depending on centered moments
 
  db.updateAll(obj);                             // All of the moments must be updated
 
  g.compute();                                   // Compute the moment
  mc.compute();                                  // Compute centered moments AFTER gravity center
  alpha.compute();                               // Compute alpha AFTER centered moments.
 
  std::cout << "--- current object ---" << std::endl;
  std::cout << "alpha=" << vpMath::deg(alpha.get()) << " deg" << std::endl;
 
  return 0;
}
  \endcode
This program outputs:
\code
--- Reference object ---
alphaRef=25.3019 deg
mu3=1.80552  0.921882  0.385828  0.122449
--- current object ---
alpha=-25.3019 deg
\endcode
 
  There is also testMomentAlpha.cpp example that shows how to compute alpha in the range \f$ [-\pi ; \pi] \f$
  using arrow images as input. The code is given below:
  \include testMomentAlpha.cpp
 
  From the first image we compute the 3rd order centered moments and the value of the reference alpha
  that is than used to compute the alpha moment in the range \f$ [-\pi ; \pi] \f$. Running this example you will get:
  \code
alpha expected 0 computed -0.128108 deg
alpha expected 45 computed 44.8881 deg
alpha expected 90 computed 89.8719 deg
alpha expected 135 computed 134.888 deg
alpha expected 180 computed 179.872 deg
alpha expected -135 computed -135.112 deg
alpha expected -90 computed -90.1281 deg
alpha expected -45 computed -45.1119 deg
  \endcode
 
  Shortcuts for quickly getting those references exist in vpMomentCommon.
 
  This moment depends on vpMomentCentered.
*/
class VISP_EXPORT vpMomentAlpha : public vpMoment
{
private:
  bool m_isRef;
  bool m_symmetric;
  std::vector<double> m_mu3Ref;
  double m_alphaRef;
  double m_symmetricThreshold;
 
public:
  vpMomentAlpha();
  vpMomentAlpha(const std::vector<double> &mu3_ref, double alpha_ref, double threshold = 1e-6);
  virtual ~vpMomentAlpha(){};
 
  void compute();
  double get() const { return values[0]; }
  const char *name() const { return "vpMomentAlpha"; }

  inline bool is_ref() const
  {
    if (m_isRef)
      return true;
    else
      return false;
  }

  inline bool is_symmetric() const
  {
    if (m_symmetric)
      return true;
    else
      return false;
  }
 
  friend VISP_EXPORT std::ostream &operator<<(std::ostream &os, const vpMomentAlpha &v);
  void printDependencies(std::ostream &os) const;
};
 
#endif