homographyRansac2DObject.cpp

Example of the Ransac homography estimation algorithm using vpHomography class.

/****************************************************************************
 *
 * This file is part of the ViSP software.
 * Copyright (C) 2005 - 2017 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
 * ("GPL") version 2 as published by the Free Software Foundation.
 * 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 http://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:
 * Example of the Ransac homography estimation algorithm.
 *
 * Authors:
 * Eric Marchand
 *
 *****************************************************************************/

#include <visp3/core/vpMath.h>
#include <visp3/core/vpRotationMatrix.h>
#include <visp3/vision/vpHomography.h>
#include <visp3/core/vpDebug.h>
#include <visp3/core/vpThetaUVector.h>

#include <visp3/core/vpPoint.h>
#include <visp3/core/vpMath.h>
#include <visp3/core/vpHomogeneousMatrix.h>
#include <visp3/core/vpDebug.h>

#include <visp3/core/vpRansac.h>
#include <visp3/io/vpParseArgv.h>
#include <stdlib.h>
// List of allowed command line options
#define GETOPTARGS  "h"

void usage(const char *name, const char *badparam);
bool getOptions(int argc, const char **argv);

void usage(const char *name, const char *badparam)
{
  fprintf(stdout, "\n\
Test the Ransac homography estimation algorithm.\n\
\n\
SYNOPSIS\n\
  %s [-h]\n", name);

  fprintf(stdout, "\n\
OPTIONS:                                               Default\n\
  -h\n\
     Print the help.\n");

  if (badparam) {
    fprintf(stderr, "ERROR: \n" );
    fprintf(stderr, "\nBad parameter [%s]\n", badparam);
  }
}
bool getOptions(int argc, const char **argv)
{
  const char *optarg_;
  int   c;
  while ((c = vpParseArgv::parse(argc, argv, GETOPTARGS, &optarg_)) > 1) {

    switch (c) {
    case 'h': usage(argv[0], NULL); return false; break;

    default:
      usage(argv[0], optarg_);
      return false; break;
    }
  }

  if ((c == 1) || (c == -1)) {
    // standalone param or error
    usage(argv[0], NULL);
    std::cerr << "ERROR: " << std::endl;
    std::cerr << "  Bad argument " << optarg_ << std::endl << std::endl;
    return false;
  }

  return true;
}


int
main(int argc, const char ** argv)
{
  try {
    // Read the command line options
    if (getOptions(argc, argv) == false) {
      exit (-1);
    }

    double L=0.1;
    unsigned int nbpt = 11;

    std::vector<vpPoint> P(nbpt);  //  Point to be tracked
    std::vector<double> xa(nbpt), ya(nbpt), xb(nbpt), yb(nbpt);

    P[0].setWorldCoordinates(-L,-L, 0 ) ;   // inlier
    P[1].setWorldCoordinates(2*L,-L, 0 ) ;  // inlier
    P[2].setWorldCoordinates(L,L, 0 ) ;  // inlier
    P[3].setWorldCoordinates(-L,3*L, 0 ) ;  // inlier
    P[4].setWorldCoordinates(0,0, L ) ;
    P[5].setWorldCoordinates(L,-2*L, L ) ;
    P[6].setWorldCoordinates(L,-4*L, 2*L ) ;
    P[7].setWorldCoordinates(-2*L,-L, -3*L ) ;
    P[8].setWorldCoordinates(-5*L,-5*L, 0 ) ;  // inlier
    P[9].setWorldCoordinates(-2*L,+3*L, 4*L ) ;
    P[10].setWorldCoordinates(-2*L,-0.5*L, 0 ) ; // inlier

    std::vector<bool> inliers_ground_truth(nbpt, false);
    inliers_ground_truth[0] = true;
    inliers_ground_truth[1] = true;
    inliers_ground_truth[2] = true;
    inliers_ground_truth[3] = true;
    inliers_ground_truth[8] = true;
    inliers_ground_truth[10] = true;

    vpHomogeneousMatrix bMo(0,0,1, 0,0,0) ;
    vpHomogeneousMatrix aMb(0.1,0.1,0.1,vpMath::rad(10),0,vpMath::rad(40)) ;
    vpHomogeneousMatrix aMo =aMb*bMo ;
    for(unsigned int i=0 ; i < nbpt ; i++)
    {
      P[i].project(aMo) ;
      xa[i] = P[i].get_x() ;
      ya[i] = P[i].get_y() ;
    }

    for(unsigned int i=0 ; i < nbpt ; i++)
    {
      P[i].project(bMo) ;
      xb[i] = P[i].get_x() ;
      yb[i] = P[i].get_y() ;
    }
    std::cout << "-------------------------------" <<std::endl ;

    vpRotationMatrix aRb  ;
    vpTranslationVector aTb ;
    vpColVector n ;
    std::cout << "Compare with built homography H = R + t/d n " << std::endl;
    vpPlane bp(0,0,1,1) ;
    vpHomography aHb_built(aMb,bp) ;
    std::cout << "aHb built from the displacement: \n" << aHb_built/aHb_built[2][2] << std::endl ;

    aHb_built.computeDisplacement(aRb, aTb, n) ;
    std::cout << "Rotation aRb: " <<std::endl ;
    std::cout << aRb << std::endl ;
    std::cout << "Translation: aTb" <<std::endl;
    std::cout << (aTb).t() <<std::endl ;
    std::cout << "Normal to the plane: n" <<std::endl;
    std::cout << (n).t() <<std::endl ;

    std::cout << "-------------------------------" <<std::endl ;
    vpHomography aHb;
    std::vector<bool> inliers;
    double residual;
    // Suppose px=1000. Set the threshold to 2 pixels => 2/1000
    // In the data we have 6 inliers. We request that at least 6 are retrieved
    vpHomography::ransac(xb, yb, xa, ya, aHb, inliers, residual, 6, 2./1000) ;

    std::cout << "aHb estimated using ransac:\n" << aHb << std::endl ;
    std::cout << "Inliers indexes (should be 0,1,2,3,8,10): ";
    for (unsigned int i=0; i< inliers.size(); i++)
      if (inliers[i]) std::cout << i << ",";
    std::cout << std::endl;

    if (inliers == inliers_ground_truth) {
      std::cout << "Ransac estimation succeed" << std::endl;
      return 0;
    }
    else {
      std::cout << "Ransac estimation fails" << std::endl;
      return 1;
    }
  }
  catch(vpException &e) {
    std::cout << "Catch an exception: " << e << std::endl;
    return 1;
  }
}