vpFeatureSegment.cpp

/*
 * ViSP, open source Visual Servoing Platform software.
 * Copyright (C) 2005 - 2025 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:
 * Segment visual feature.
 */

 
#include <cmath>
#include <visp3/core/vpDisplay.h>
#include <visp3/core/vpImagePoint.h>
#include <visp3/core/vpMath.h>
#include <visp3/core/vpMeterPixelConversion.h>
#include <visp3/visual_features/vpBasicFeature.h>
#include <visp3/visual_features/vpFeatureSegment.h>
 
// Exception
#include <visp3/core/vpException.h>
 
// Debug trace
#include <visp3/core/vpDebug.h>
 
BEGIN_VISP_NAMESPACE

  void vpFeatureSegment::init()
{
  // feature dimension
  dim_s = 4;
  nbParameters = 6;
 
  // memory allocation
  s.resize(dim_s);
  if (flags == nullptr)
    flags = new bool[nbParameters];
  for (unsigned int i = 0; i < nbParameters; i++)
    flags[i] = false;
}

vpFeatureSegment::vpFeatureSegment(bool normalized)
  : xc_(0), yc_(0), l_(0), alpha_(0), Z1_(0), Z2_(0), cos_a_(0), sin_a_(0), normalized_(normalized)
{
  init();
}

vpMatrix vpFeatureSegment::interaction(unsigned int select)
{
  vpMatrix L;
  L.resize(0, 6);
 
  if (deallocate == vpBasicFeature::user) {
    for (unsigned int i = 0; i < nbParameters; i++) {
      if (flags[i] == false) {
        switch (i) {
        case 0:
          vpTRACE("Warning !!!  The interaction matrix is computed but xc "
                  "was not set yet");
          break;
        case 1:
          vpTRACE("Warning !!!  The interaction matrix is computed but Yc "
                  "was not set yet");
          break;
        case 2:
          vpTRACE("Warning !!!  The interaction matrix is computed but l was "
                  "not set yet");
          break;
        case 3:
          vpTRACE("Warning !!!  The interaction matrix is computed but alpha "
                  "was not set yet");
          break;
        case 4:
          vpTRACE("Warning !!!  The interaction matrix is computed but Z1 "
                  "was not set yet");
          break;
        case 5:
          vpTRACE("Warning !!!  The interaction matrix is computed but Z2 "
                  "was not set yet");
          break;
        default:
          vpTRACE("Problem during the reading of the variable flags");
        }
      }
    }
  }
 
  // This version is a simplification
  double lambda1 = (Z1_ - Z2_) / (Z1_ * Z2_);     // -l * lambda
  double lambda2 = (Z1_ + Z2_) / (2 * Z1_ * Z2_); // 1/Zm
 
  if (normalized_) {
    // here var xc_ contains xc/l, yc_ contains yc/l and l_ contains 1/l
    double xn = xc_;
    double yn = yc_;
    double ln = l_;
    double lambda = -lambda1 * ln;
    double Zn_inv = lambda2 * ln;
    double lc = cos_a_ / ln;
    double ls = sin_a_ / ln;
    double xnalpha = xn * cos_a_ + yn * sin_a_;
    double lnc = cos_a_ * ln;
    double lns = sin_a_ * ln;
 
    if (vpFeatureSegment::selectXc() & select) {
      vpMatrix Lxn(1, 6);
      Lxn[0][0] = -Zn_inv + lambda * xn * cos_a_;
      Lxn[0][1] = lambda * xn * sin_a_;
      Lxn[0][2] = lambda1 * (xn * xnalpha - cos_a_ / 4.);
      Lxn[0][3] = sin_a_ * cos_a_ / 4 / ln - xn * xnalpha * sin_a_ / ln;
      Lxn[0][4] = -ln * (1. + lc * lc / 4.) + xn * xnalpha * cos_a_ / ln;
      Lxn[0][5] = yn;
      L = vpMatrix::stack(L, Lxn);
    }
 
    if (vpFeatureSegment::selectYc() & select) {
      vpMatrix Lyn(1, 6);
      Lyn[0][0] = lambda * yn * cos_a_;
      Lyn[0][1] = -Zn_inv + lambda * yn * sin_a_;
      Lyn[0][2] = lambda1 * (yn * xnalpha - sin_a_ / 4.);
      Lyn[0][3] = ln * (1 + ls * ls / 4.) - yn * xnalpha * sin_a_ / ln;
      Lyn[0][4] = -sin_a_ * cos_a_ / 4 / ln + yn * xnalpha * cos_a_ / ln;
      Lyn[0][5] = -xn;
      L = vpMatrix::stack(L, Lyn);
    }
 
    if (vpFeatureSegment::selectL() & select) {
      vpMatrix Lln(1, 6);
      Lln[0][0] = lambda * lnc;
      Lln[0][1] = lambda * lns;
      Lln[0][2] = -(Zn_inv + lambda * xnalpha);
      Lln[0][3] = -yn - xnalpha * sin_a_;
      Lln[0][4] = xn + xnalpha * cos_a_;
      Lln[0][5] = 0;
      L = vpMatrix::stack(L, Lln);
    }
    if (vpFeatureSegment::selectAlpha() & select) {
      // We recall that xc_ contains xc/l, yc_ contains yc/l and l_ contains
      // 1/l
      vpMatrix Lalpha(1, 6);
      Lalpha[0][0] = -lambda1 * sin_a_ * l_;
      Lalpha[0][1] = lambda1 * cos_a_ * l_;
      Lalpha[0][2] = lambda1 * (xc_ * sin_a_ - yc_ * cos_a_);
      Lalpha[0][3] = (-xc_ * sin_a_ * sin_a_ + yc_ * cos_a_ * sin_a_) / l_;
      Lalpha[0][4] = (xc_ * cos_a_ * sin_a_ - yc_ * cos_a_ * cos_a_) / l_;
      Lalpha[0][5] = -1;
      L = vpMatrix::stack(L, Lalpha);
    }
  }
  else {
    if (vpFeatureSegment::selectXc() & select) {
      vpMatrix Lxc(1, 6);
      Lxc[0][0] = -lambda2;
      Lxc[0][1] = 0.;
      Lxc[0][2] = lambda2 * xc_ - lambda1 * l_ * cos_a_ / 4.;
      Lxc[0][3] = xc_ * yc_ + l_ * l_ * cos_a_ * sin_a_ / 4.;
      Lxc[0][4] = -(1 + xc_ * xc_ + l_ * l_ * cos_a_ * cos_a_ / 4.);
      Lxc[0][5] = yc_;
      L = vpMatrix::stack(L, Lxc);
    }
 
    if (vpFeatureSegment::selectYc() & select) {
      vpMatrix Lyc(1, 6);
      Lyc[0][0] = 0.;
      Lyc[0][1] = -lambda2;
      Lyc[0][2] = lambda2 * yc_ - lambda1 * l_ * sin_a_ / 4.;
      Lyc[0][3] = 1 + yc_ * yc_ + l_ * l_ * sin_a_ * sin_a_ / 4.;
      Lyc[0][4] = -xc_ * yc_ - l_ * l_ * cos_a_ * sin_a_ / 4.;
      Lyc[0][5] = -xc_;
      L = vpMatrix::stack(L, Lyc);
    }
 
    if (vpFeatureSegment::selectL() & select) {
      vpMatrix Ll(1, 6);
      Ll[0][0] = lambda1 * cos_a_;
      Ll[0][1] = lambda1 * sin_a_;
      Ll[0][2] = lambda2 * l_ - lambda1 * (xc_ * cos_a_ + yc_ * sin_a_);
      Ll[0][3] = l_ * (xc_ * cos_a_ * sin_a_ + yc_ * (1 + sin_a_ * sin_a_));
      Ll[0][4] = -l_ * (xc_ * (1 + cos_a_ * cos_a_) + yc_ * cos_a_ * sin_a_);
      Ll[0][5] = 0;
      L = vpMatrix::stack(L, Ll);
    }
    if (vpFeatureSegment::selectAlpha() & select) {
      vpMatrix Lalpha(1, 6);
      Lalpha[0][0] = -lambda1 * sin_a_ / l_;
      Lalpha[0][1] = lambda1 * cos_a_ / l_;
      Lalpha[0][2] = lambda1 * (xc_ * sin_a_ - yc_ * cos_a_) / l_;
      Lalpha[0][3] = -xc_ * sin_a_ * sin_a_ + yc_ * cos_a_ * sin_a_;
      Lalpha[0][4] = xc_ * cos_a_ * sin_a_ - yc_ * cos_a_ * cos_a_;
      Lalpha[0][5] = -1;
      L = vpMatrix::stack(L, Lalpha);
    }
  }
 
  return L;
}

vpColVector vpFeatureSegment::error(const vpBasicFeature &s_star, unsigned int select)
{
  vpColVector e(0);
 
  if (vpFeatureSegment::selectXc() & select) {
    vpColVector exc(1);
    exc[0] = xc_ - s_star[0];
    e = vpColVector::stack(e, exc);
  }
 
  if (vpFeatureSegment::selectYc() & select) {
    vpColVector eyc(1);
    eyc[0] = yc_ - s_star[1];
    e = vpColVector::stack(e, eyc);
  }
 
  if (vpFeatureSegment::selectL() & select) {
    vpColVector eL(1);
    eL[0] = l_ - s_star[2];
    e = vpColVector::stack(e, eL);
  }
 
  if (vpFeatureSegment::selectAlpha() & select) {
    vpColVector eAlpha(1);
    eAlpha[0] = alpha_ - s_star[3];
    while (eAlpha[0] < -M_PI)
      eAlpha[0] += 2 * M_PI;
    while (eAlpha[0] > M_PI)
      eAlpha[0] -= 2 * M_PI;
    e = vpColVector::stack(e, eAlpha);
  }
  return e;
}

void vpFeatureSegment::print(unsigned int select) const
{
  std::cout << "vpFeatureSegment: (";
  if (vpFeatureSegment::selectXc() & select) {
    if (normalized_)
      std::cout << "xn = ";
    else
      std::cout << "xc = ";
    std::cout << s[0] << "; ";
  }
  if (vpFeatureSegment::selectYc() & select) {
    if (normalized_)
      std::cout << "yn = ";
    else
      std::cout << "yc = ";
    std::cout << s[1] << "; ";
  }
  if (vpFeatureSegment::selectL() & select) {
    if (normalized_)
      std::cout << "ln = ";
    else
      std::cout << "l = ";
    std::cout << s[2] << "; ";
  }
  if (vpFeatureSegment::selectAlpha() & select) {
    std::cout << "alpha = " << vpMath::deg(s[3]) << " deg";
  }
  std::cout << ")" << std::endl;
}

vpFeatureSegment *vpFeatureSegment::duplicate() const
{
  vpFeatureSegment *feature;
 
  feature = new vpFeatureSegment(*this);
  return feature;
}

void vpFeatureSegment::display(const vpCameraParameters &cam, const vpImage<unsigned char> &I, const vpColor &color,
                               unsigned int thickness) const
{
  double l, x, y;
  if (normalized_) {
    l = 1. / l_;
    x = xc_ * l;
    y = yc_ * l;
  }
  else {
    l = l_;
    x = xc_;
    y = yc_;
  }
 
  double x1 = x - (l / 2.) * cos_a_;
  double x2 = x + (l / 2.) * cos_a_;
 
  double y1 = y - (l / 2.) * sin_a_;
  double y2 = y + (l / 2.) * sin_a_;
  vpImagePoint ip1, ip2;
 
  vpMeterPixelConversion::convertPoint(cam, x1, y1, ip1);
  vpMeterPixelConversion::convertPoint(cam, x2, y2, ip2);
  vpDisplay::displayLine(I, ip1, ip2, color, thickness);
  vpDisplay::displayCircle(I, ip1, 5, color, true);
  vpDisplay::displayCircle(I, ip2, 5, vpColor::yellow, true);
}

void vpFeatureSegment::display(const vpCameraParameters &cam, const vpImage<vpRGBa> &I, const vpColor &color,
                               unsigned int thickness) const
{
  double l, x, y;
  if (normalized_) {
    l = 1. / l_;
    x = xc_ * l;
    y = yc_ * l;
  }
  else {
    l = l_;
    x = xc_;
    y = yc_;
  }
 
  double x1 = x - (l / 2.) * cos_a_;
  double x2 = x + (l / 2.) * cos_a_;
 
  double y1 = y - (l / 2.) * sin_a_;
  double y2 = y + (l / 2.) * sin_a_;
  vpImagePoint ip1, ip2;
 
  vpMeterPixelConversion::convertPoint(cam, x1, y1, ip1);
  vpMeterPixelConversion::convertPoint(cam, x2, y2, ip2);
  vpDisplay::displayLine(I, ip1, ip2, color, thickness);
  vpDisplay::displayCircle(I, ip1, 5, vpColor::cyan, true);
  vpDisplay::displayCircle(I, ip2, 5, vpColor::yellow, true);
}

vpFeatureSegment &vpFeatureSegment::buildFrom(const double &x1, const double &y1, const double &Z1, const double &x2, const double &y2, const double &Z2)
{
  double l = sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
  double x_c = (x1 + x2) / 2.;
  double y_c = (y1 + y2) / 2.;
  double alpha = atan2(y1 - y2, x1 - x2);
 
  if (normalized_) {
    setXc(x_c / l);
    setYc(y_c / l);
    setL(1 / l);
    setAlpha(alpha);
 
    setZ1(Z1);
    setZ2(Z2);
  }
  else {
    setXc(x_c);
    setYc(y_c);
    setL(l);
    setAlpha(alpha);
 
    setZ1(Z1);
    setZ2(Z2);
  }
  return *this;
}

unsigned int vpFeatureSegment::selectXc()
{
  return FEATURE_LINE[0];
}

unsigned int vpFeatureSegment::selectYc()
{
  return FEATURE_LINE[1];
}

unsigned int vpFeatureSegment::selectL()
{
  return FEATURE_LINE[2];
}

unsigned int vpFeatureSegment::selectAlpha()
{
  return FEATURE_LINE[3];
}
 
END_VISP_NAMESPACE