vpMbKltTracker.cpp

/****************************************************************************
 *
 * $Id: vpMbKltTracker.cpp 4337 2013-07-23 13:57:53Z ayol $
 *
 * This file is part of the ViSP software.
 * Copyright (C) 2005 - 2013 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://www.irisa.fr/lagadic/visp/visp.html for more information.
 *
 * This software was developed at:
 * INRIA Rennes - Bretagne Atlantique
 * Campus Universitaire de Beaulieu
 * 35042 Rennes Cedex
 * France
 * http://www.irisa.fr/lagadic
 *
 * 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:
 * Model based tracker using only KLT
 *
 * Authors:
 * Romain Tallonneau
 * Aurelien Yol
 *
 *****************************************************************************/

#include <visp/vpMbKltTracker.h>

#ifdef VISP_HAVE_OPENCV

vpMbKltTracker::vpMbKltTracker()
{
  
  cur = NULL;
  compute_interaction = true;
  firstInitialisation = true;
  computeCovariance = false;
  firstTrack = false;
  
  tracker.setTrackerId(1);
  tracker.setUseHarris(1);
  
  tracker.setMaxFeatures(10000);
  tracker.setWindowSize(5);
  tracker.setQuality(0.01);
  tracker.setMinDistance(5);
  tracker.setHarrisFreeParameter(0.01);
  tracker.setBlockSize(3);
  tracker.setPyramidLevels(3);
  
  angleAppears = vpMath::rad(65);
  angleDisappears = vpMath::rad(75);
  
  clippingFlag = vpMbtPolygon::NO_CLIPPING;
  
  maskBorder = 5;
  threshold_outlier = 0.5;
  percentGood = 0.6;
  
  lambda = 0.8;
  maxIter = 200;

#ifdef VISP_HAVE_OGRE
  faces.getOgreContext()->setWindowName("MBT KLT");
#endif
  
  useOgre = false;
}

vpMbKltTracker::~vpMbKltTracker()
{
  if(cur != NULL){
    cvReleaseImage(&cur);
    cur = NULL;
  }
}

void 
vpMbKltTracker::init(const vpImage<unsigned char>& I)
{
  if(!modelInitialised){
    throw vpException(vpException::fatalError, "model not initialized");
  }
  
 bool reInitialisation = false;
  if(!useOgre)
    faces.setVisible(I, cam, cMo, angleAppears, angleDisappears, reInitialisation);
  else{
#ifdef VISP_HAVE_OGRE   
    if(!faces.isOgreInitialised()){
      faces.setBackgroundSizeOgre(I.getHeight(), I.getWidth());
      faces.initOgre(cam);
    }
    
    faces.setVisibleOgre(I, cam, cMo, angleAppears, angleDisappears, reInitialisation);
    
#else
    faces.setVisible(I, cam, cMo, angleAppears, angleDisappears, reInitialisation);
#endif
  }
  
  reinit(I);
}

void 
vpMbKltTracker::reinit(const vpImage<unsigned char>& I)
{  
  c0Mo = cMo;
  ctTc0.setIdentity();
  firstTrack = false;

  vpImageConvert::convert(I, cur);
  
  // mask
  IplImage* mask = cvCreateImage(cvSize((int)I.getWidth(), (int)I.getHeight()), IPL_DEPTH_8U, 1);
  cvZero(mask);
  
  for (unsigned int i = 0; i < faces.size(); i += 1){
    if(faces[i]->isVisible())
      faces[i]->updateMask(mask, 255/* - i*15*/, maskBorder);
  }
  
  tracker.initTracking(cur, mask);
  
  for (unsigned int i = 0; i < faces.size(); i += 1){
    if(faces[i]->isVisible()){
      faces[i]->init(tracker);
    }
  }

  cvReleaseImage(&mask);
}

void            
vpMbKltTracker::resetTracker()
{
  cMo.setIdentity();
  
  if(cur != NULL){
    cvReleaseImage(&cur);
    cur = NULL;
  }
  
  compute_interaction = true;
  firstInitialisation = true;
  computeCovariance = false;
  firstTrack = false;

  tracker.setTrackerId(1);
  tracker.setUseHarris(1);
  
  tracker.setMaxFeatures(10000);
  tracker.setWindowSize(5);
  tracker.setQuality(0.01);
  tracker.setMinDistance(5);
  tracker.setHarrisFreeParameter(0.01);
  tracker.setBlockSize(3);
  tracker.setPyramidLevels(3);
  
  angleAppears = vpMath::rad(65);
  angleDisappears = vpMath::rad(75);
  
  clippingFlag = vpMbtPolygon::NO_CLIPPING;
  
  maskBorder = 5;
  threshold_outlier = 0.5;
  percentGood = 0.7;
  
  lambda = 0.8;
  maxIter = 200;
  
  faces.reset();
  
#ifdef VISP_HAVE_OGRE
  useOgre = false;
#endif
}

std::vector<vpImagePoint> 
vpMbKltTracker::getKltImagePoints() const
{
  std::vector<vpImagePoint> kltPoints;
  for (unsigned int i = 0; i < static_cast<unsigned int>(tracker.getNbFeatures()); i ++){
    int id;
    float x_tmp, y_tmp;
    tracker.getFeature((int)i, id, x_tmp, y_tmp);
    kltPoints.push_back(vpImagePoint(y_tmp, x_tmp));
  }
  
  return kltPoints;
}

std::map<int, vpImagePoint> 
vpMbKltTracker::getKltImagePointsWithId() const
{
  std::map<int, vpImagePoint> kltPoints;
  for (unsigned int i = 0; i < static_cast<unsigned int>(tracker.getNbFeatures()); i ++){
    int id;
    float x_tmp, y_tmp;
    tracker.getFeature((int)i, id, x_tmp, y_tmp);
    kltPoints[id] = vpImagePoint(y_tmp, x_tmp);
  }
  
  return kltPoints;
}

void            
vpMbKltTracker::setKltOpencv(const vpKltOpencv& t){
  tracker.setMaxFeatures(t.getMaxFeatures());
  tracker.setWindowSize(t.getWindowSize());
  tracker.setQuality(t.getQuality());
  tracker.setMinDistance(t.getMinDistance());
  tracker.setHarrisFreeParameter(t.getHarrisFreeParameter());
  tracker.setBlockSize(t.getBlockSize());
  tracker.setPyramidLevels(t.getPyramidLevels());
}

void
vpMbKltTracker::setCameraParameters(const vpCameraParameters& cam)
{
  for (unsigned int i = 0; i < faces.size(); i += 1){
    faces[i]->setCameraParameters(cam);
  }
  this->cam = cam;
}
   
void    
vpMbKltTracker::setOgreVisibilityTest(const bool &v) 
{
  useOgre = v; 
  if(useOgre){
#ifndef VISP_HAVE_OGRE     
    useOgre = false;
    std::cout << "WARNING: ViSP doesn't have Ogre3D, basic visibility test will be used. setOgreVisibilityTest() set to false." << std::endl;
#endif
  }
}

void           
vpMbKltTracker::setPose(const vpImage<unsigned char> &I, const vpHomogeneousMatrix& cdMo)
{
  if(firstTrack){
    bool reInitialisation = false;
    if(!useOgre)
      faces.setVisible(I, cam, cdMo, angleAppears, angleDisappears, reInitialisation);
    else{
  #ifdef VISP_HAVE_OGRE    
      faces.setVisibleOgre(I, cam, cdMo, angleAppears, angleDisappears, reInitialisation);
  #else
      faces.setVisible(I, cam, cdMo, angleAppears, angleDisappears, reInitialisation);
  #endif
    }
    
    if(reInitialisation){
      std::cout << "WARNING: Visibility changed, must reinitialize to update pose" << std::endl;
      cMo = cdMo;
      reinit(I);
    }
    else{
      vpHomogeneousMatrix cdMc = cdMo * cMo.inverse();
      vpHomogeneousMatrix cMcd = cdMc.inverse();
      
      vpRotationMatrix cdRc;
      vpTranslationVector cdtc;
      
      cdMc.extract(cdRc);
      cdMc.extract(cdtc);
      
      CvPoint2D32f* initial_guess = NULL;
      initial_guess = (CvPoint2D32f*)cvAlloc((unsigned int)tracker.getMaxFeatures()*sizeof(initial_guess[0]));
        
      for (unsigned int i = 0; i < faces.size(); i += 1){
        if(faces[i]->isVisible() && faces[i]->hasEnoughPoints()){  
          //Get the normal to the face at the current state cMo
          vpPlane plan(faces[i]->p[0], faces[i]->p[1], faces[i]->p[2]);
          plan.changeFrame(cMcd);
          
          vpColVector Nc = plan.getNormal(); 
          Nc.normalize();
          
          double invDc = 1.0 / plan.getD();
          
          //Create the homography
          vpHomography cdHc;
          vpGEMM(cdtc, Nc, -invDc, cdRc, 1.0, cdHc, VP_GEMM_B_T);
          cdHc /= cdHc[2][2];
          
          //Create the 2D homography
          vpMatrix cdGc = cam.get_K() * cdHc * cam.get_K_inverse();
          
          //Points displacement
          std::map<int, vpImagePoint>::const_iterator iter = faces[i]->getCurrentPoints().begin();
          for( ; iter != faces[i]->getCurrentPoints().end(); iter++){
            vpColVector cdp(3);
            cdp[0] = iter->second.get_j(); cdp[1] = iter->second.get_i(); cdp[2] = 1.0;
            
            double p_mu_t_2 = cdp[0] * cdGc[2][0] + cdp[1] * cdGc[2][1] + cdGc[2][2];

            if( fabs(p_mu_t_2) < std::numeric_limits<double>::epsilon()){
              cdp[0] = 0.0;
              cdp[1] = 0.0;
              throw vpException(vpException::divideByZeroError, "the depth of the point is calculated to zero");
            }

            cdp[0] = (cdp[0] * cdGc[0][0] + cdp[1] * cdGc[0][1] + cdGc[0][2]) / p_mu_t_2;
            cdp[1] = (cdp[0] * cdGc[1][0] + cdp[1] * cdGc[1][1] + cdGc[1][2]) / p_mu_t_2;
            
            //Set value to the KLT tracker
            initial_guess[(faces[i]->getCurrentPointsInd())[iter->first]].x = (float)cdp[0];
            initial_guess[(faces[i]->getCurrentPointsInd())[iter->first]].y = (float)cdp[1];
          }
        }
      }  
      
      tracker.setInitialGuess(&initial_guess);
      
      if(initial_guess) cvFree(&initial_guess);
      initial_guess = NULL;
      
      cMo = cdMo;
    }
  }
}

void            
vpMbKltTracker::setFarClippingDistance(const double &dist) 
{ 
  if( (clippingFlag & vpMbtPolygon::NEAR_CLIPPING) == vpMbtPolygon::NEAR_CLIPPING && dist <= distNearClip)
    vpTRACE("Far clipping value cannot be inferior than near clipping value. Far clipping won't be considered.");
  else if ( dist < 0 ) 
    vpTRACE("Far clipping value cannot be inferior than 0. Far clipping won't be considered.");
  else{   
    clippingFlag = (clippingFlag | vpMbtPolygon::FAR_CLIPPING);
    distFarClip = dist; 
    for (unsigned int i = 0; i < faces.size(); i ++){
      faces[i]->setFarClippingDistance(distFarClip);
    }  
  }
}

void           
vpMbKltTracker::setNearClippingDistance(const double &dist) 
{ 
  if( (clippingFlag & vpMbtPolygon::FAR_CLIPPING) == vpMbtPolygon::FAR_CLIPPING && dist >= distFarClip)
    vpTRACE("Near clipping value cannot be superior than far clipping value. Near clipping won't be considered.");
  else if ( dist < 0 ) 
    vpTRACE("Near clipping value cannot be inferior than 0. Near clipping won't be considered.");
  else{
    clippingFlag = (clippingFlag | vpMbtPolygon::NEAR_CLIPPING);
    distNearClip = dist; 
    for (unsigned int i = 0; i < faces.size(); i ++){
      faces[i]->setNearClippingDistance(distNearClip);
    } 
  }
}

void            
vpMbKltTracker::setClipping(const unsigned int &flags) 
{ 
  clippingFlag = flags;
  for (unsigned int i = 0; i < faces.size(); i ++)
    faces[i]->setClipping(clippingFlag);
}
          
void
vpMbKltTracker::initFaceFromCorners(const std::vector<vpPoint>& corners, const unsigned int indexFace)
{     
  if( corners.size() > 2){ // This tracker can't handle lignes
    vpMbtKltPolygon *polygon = new vpMbtKltPolygon;
  //   polygon->setCameraParameters(cam);
    polygon->setNbPoint((unsigned int)corners.size());
    polygon->setIndex((int)indexFace);
    for(unsigned int j = 0; j < corners.size(); j++) {
      polygon->addPoint(j, corners[j]);
    }
    faces.addPolygon(polygon);
    faces.getPolygon().back()->setCameraParameters(cam);
    
    if(clippingFlag != vpMbtPolygon::NO_CLIPPING)
      faces.getPolygon().back()->setClipping(clippingFlag);
    
    if((clippingFlag & vpMbtPolygon::NEAR_CLIPPING) == vpMbtPolygon::NEAR_CLIPPING)
      faces.getPolygon().back()->setNearClippingDistance(distNearClip);
    
    if((clippingFlag & vpMbtPolygon::FAR_CLIPPING) == vpMbtPolygon::FAR_CLIPPING)
      faces.getPolygon().back()->setFarClippingDistance(distFarClip);

    delete polygon;
    polygon = NULL;
  }
}

void
vpMbKltTracker::preTracking(const vpImage<unsigned char>& I, unsigned int &nbInfos, unsigned int &nbFaceUsed)
{
  vpImageConvert::convert(I, cur);
  tracker.track(cur);
  
  if(!firstTrack)
    firstTrack = true;
  
  nbInfos = 0;  
  nbFaceUsed = 0;
  for (unsigned int i = 0; i < faces.size(); i += 1){
    if(faces[i]->isVisible()){
      faces[i]->computeNbDetectedCurrent(tracker);
//       faces[i]->ransac();
      if(faces[i]->hasEnoughPoints()){
        nbInfos += faces[i]->getNbPointsCur();
        nbFaceUsed++;
      }
    }
  } 
}

bool
vpMbKltTracker::postTracking(const vpImage<unsigned char>& I, vpColVector &w)
{
  // # For a better Post Tracking, tracker should reinitialize if so faces don't have enough points but are visible.
  // # Here we are not doing it for more speed performance.
  bool reInitialisation = false;
  
  unsigned int initialNumber = 0;
  unsigned int currentNumber = 0;
  unsigned int shift = 0;
  for (unsigned int i = 0; i < faces.size(); i += 1){
    if(faces[i]->isVisible()){
      initialNumber += faces[i]->getInitialNumberPoint();
      if(faces[i]->hasEnoughPoints()){    
        vpSubColVector sub_w(w, shift, 2*faces[i]->getNbPointsCur());
        faces[i]->removeOutliers(sub_w, threshold_outlier);
        shift += 2*faces[i]->getNbPointsCur();
        
        currentNumber += faces[i]->getNbPointsCur();
      }
//       else{
//         reInitialisation = true;
//         break;
//       }
    }
  }
  
//   if(!reInitialisation){
    double value = percentGood * (double)initialNumber;
    if((double)currentNumber < value){
//     std::cout << "Too many point disappear : " << initialNumber << "/" << currentNumber << std::endl;
      reInitialisation = true;
    }
    else{
      if(!useOgre)
        faces.setVisible(I, cam, cMo, angleAppears, angleDisappears, reInitialisation);
      else{
#ifdef VISP_HAVE_OGRE    
        faces.setVisibleOgre(I, cam, cMo, angleAppears, angleDisappears, reInitialisation);
#else
        faces.setVisible(I, cam, cMo, angleAppears, angleDisappears, reInitialisation);
#endif
      }
    }
//   }
  
  if(reInitialisation)
    return true;
  
  return false;
}

void
vpMbKltTracker::computeVVS(const unsigned int &nbInfos, vpColVector &w)
{
  vpMatrix J;     // interaction matrix
  vpColVector R;  // residu
  vpMatrix J_true;     // interaction matrix
  vpColVector R_true;  // residu
  vpColVector v;  // "speed" for VVS
  vpHomography H;
  vpColVector w_true;
  vpRobust robust(2*nbInfos);

  vpMatrix JTJ, JTR;
  
  double normRes = 0;
  double normRes_1 = -1;
  unsigned int iter = 0;

  R.resize(2*nbInfos);
  J.resize(2*nbInfos, 6, 0);
  
  while( ((int)((normRes - normRes_1)*1e8) != 0 )  && (iter<maxIter) ){
    
    unsigned int shift = 0;
    for (unsigned int i = 0; i < faces.size(); i += 1){
      if(faces[i]->isVisible() && faces[i]->hasEnoughPoints()){
        vpSubColVector subR(R, shift, 2*faces[i]->getNbPointsCur());
        vpSubMatrix subJ(J, shift, 0, 2*faces[i]->getNbPointsCur(), 6);
        try{
          faces[i]->computeHomography(ctTc0, H);
          faces[i]->computeInteractionMatrixAndResidu(subR, subJ);
        }catch(...){
          std::cerr << "exception while tracking face " << i << std::endl;
          throw ;
        }

        shift += 2*faces[i]->getNbPointsCur();
      }
    }

      /* robust */
    if(iter == 0){
      w_true.resize(2*nbInfos);
      w.resize(2*nbInfos);
      w = 1;
    }
    robust.setIteration(iter);
    robust.setThreshold(2/cam.get_px());
    robust.MEstimator( vpRobust::TUKEY, R, w);
    
    if(computeCovariance){
      R_true = R;
      J_true = J;
    }

    normRes_1 = normRes;
    normRes = 0;
    for (unsigned int i = 0; i < static_cast<unsigned int>(R.getRows()); i += 1){
      w_true = w[i] * w[i];
      R[i] = R[i] * w[i];
      normRes += R[i];
    }

    if((iter == 0) || compute_interaction){
      for(unsigned int i=0; i<static_cast<unsigned int>(R.getRows()); i++){
        for(unsigned int j=0; j<6; j++){
          J[i][j] *= w[i];
        }
      }
    }
    
    JTJ = J.AtA();
    computeJTR(J, R, JTR);
    v = -lambda * JTJ.pseudoInverse(1e-16) * JTR;
    
    ctTc0 = vpExponentialMap::direct(v).inverse() * ctTc0;
    
    iter++;
  }
  
  if(computeCovariance){
    vpMatrix D;
    D.diag(w_true);
    covarianceMatrix = vpMatrix::computeCovarianceMatrix(J_true,v,-lambda*R_true,D);
  }
  
  cMo = ctTc0 * c0Mo;
}

void
vpMbKltTracker::track(const vpImage<unsigned char>& I)
{   
  unsigned int nbInfos;
  unsigned int nbFaceUsed;
  preTracking(I, nbInfos, nbFaceUsed);
  
  if(nbInfos < 4 || nbFaceUsed == 0){
    vpERROR_TRACE("\n\t\t Error-> not enough data") ;
    throw vpTrackingException(vpTrackingException::notEnoughPointError, "\n\t\t Error-> not enough data");
  }

  vpColVector w;
  computeVVS(nbInfos, w);  

  if(postTracking(I, w))
    reinit(I);
}

void 
vpMbKltTracker::loadConfigFile(const std::string& configFile)
{
  vpMbKltTracker::loadConfigFile(configFile.c_str());
}

void
vpMbKltTracker::loadConfigFile(const char* configFile)
{
#ifdef VISP_HAVE_XML2
  vpMbtKltXmlParser xmlp;
  
  xmlp.setMaxFeatures(10000);
  xmlp.setWindowSize(5);
  xmlp.setQuality(0.01);
  xmlp.setMinDistance(5);
  xmlp.setHarrisParam(0.01);
  xmlp.setBlockSize(3);
  xmlp.setPyramidLevels(3);
  xmlp.setMaskBorder(maskBorder);
  xmlp.setAngleAppear(vpMath::deg(angleAppears));
  xmlp.setAngleDisappear(vpMath::deg(angleDisappears));
  
  try{
    std::cout << " *********** Parsing XML for MBT KLT Tracker ************ " << std::endl;
    
    xmlp.parse(configFile);
  }
  catch(...){
    vpERROR_TRACE("Can't open XML file \"%s\"\n ", configFile);
    throw vpException(vpException::ioError, "problem to parse configuration file.");
  }

  vpCameraParameters camera;
  xmlp.getCameraParameters(camera);
  setCameraParameters(camera); 
  
  tracker.setMaxFeatures((int)xmlp.getMaxFeatures());
  tracker.setWindowSize((int)xmlp.getWindowSize());
  tracker.setQuality(xmlp.getQuality());
  tracker.setMinDistance(xmlp.getMinDistance());
  tracker.setHarrisFreeParameter(xmlp.getHarrisParam());
  tracker.setBlockSize((int)xmlp.getBlockSize());
  tracker.setPyramidLevels((int)xmlp.getPyramidLevels());
  maskBorder = xmlp.getMaskBorder();
  angleAppears = vpMath::rad(xmlp.getAngleAppear());
  angleDisappears = vpMath::rad(xmlp.getAngleDisappear());
  
  if(xmlp.hasNearClippingDistance())
    setNearClippingDistance(xmlp.getNearClippingDistance());
  
  if(xmlp.hasFarClippingDistance())
    setFarClippingDistance(xmlp.getFarClippingDistance());
  
  if(xmlp.getFovClipping())
    clippingFlag = clippingFlag | vpMbtPolygon::FOV_CLIPPING;
#else
  vpTRACE("You need the libXML2 to read the config file %s", configFile);
#endif
}

void
vpMbKltTracker::display(const vpImage<unsigned char>& I, const vpHomogeneousMatrix &cMo, const vpCameraParameters & cam,
                        const vpColor& col , const unsigned int thickness, const bool displayFullModel)
{
  vpCameraParameters c = cam;
  
  if(clippingFlag > 3) // Contains at least one FOV constraint
    c.computeFov(I.getWidth(), I.getHeight());
  
  for (unsigned int i = 0; i < faces.size(); i += 1){
    if(displayFullModel || faces[i]->isVisible())
    {
      faces[i]->changeFrame(cMo);
      faces[i]->computeRoiClipped(c);
      std::vector<std::pair<vpImagePoint,unsigned int> > roi;
      faces[i]->getRoiClipped(c, roi);
      
      for (unsigned int j = 0; j < roi.size(); j += 1){
        if(((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::NEAR_CLIPPING) == 0) && 
           ((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::FAR_CLIPPING) == 0) && 
           ((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::DOWN_CLIPPING) == 0) && 
           ((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::UP_CLIPPING) == 0) && 
           ((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::LEFT_CLIPPING) == 0) && 
           ((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::RIGHT_CLIPPING) == 0)){
          vpImagePoint ip1, ip2;
          ip1 = roi[j].first;
          ip2 = roi[(j+1)%roi.size()].first;
          
          vpDisplay::displayLine (I, ip1, ip2, col, thickness);
        }
      }
    }
    if(displayFeatures && faces[i]->hasEnoughPoints() && faces[i]->isVisible()) {
        faces[i]->displayPrimitive(I);
//         faces[i]->displayNormal(I);
    }
  }

#ifdef VISP_HAVE_OGRE
  if(useOgre)
    faces.displayOgre(cMo);
#endif
}

void
vpMbKltTracker::display(const vpImage<vpRGBa>& I, const vpHomogeneousMatrix &cMo, const vpCameraParameters & cam,
                        const vpColor& col , const unsigned int thickness, const bool displayFullModel)
{
  vpCameraParameters c = cam;
  
  if(clippingFlag > 3) // Contains at least one FOV constraint
    c.computeFov(I.getWidth(), I.getHeight());
  
  for (unsigned int i = 0; i < faces.size(); i += 1){
    if(displayFullModel || faces[i]->isVisible())
    {
      faces[i]->changeFrame(cMo);
      faces[i]->computeRoiClipped(c);      
      std::vector<std::pair<vpImagePoint,unsigned int> > roi;
      faces[i]->getRoiClipped(c, roi);
      
      for (unsigned int j = 0; j < roi.size(); j += 1){
        if(((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::NEAR_CLIPPING) == 0) && 
           ((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::FAR_CLIPPING) == 0) && 
           ((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::DOWN_CLIPPING) == 0) && 
           ((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::UP_CLIPPING) == 0) && 
           ((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::LEFT_CLIPPING) == 0) && 
           ((roi[(j+1)%roi.size()].second & roi[j].second & vpMbtPolygon::RIGHT_CLIPPING) == 0)){
          vpImagePoint ip1, ip2;
          ip1 = roi[j].first;
          ip2 = roi[(j+1)%roi.size()].first;
          
          vpDisplay::displayLine (I, ip1, ip2, col, thickness);
        }
      }
    }
    if(displayFeatures && faces[i]->hasEnoughPoints() && faces[i]->isVisible()) {
        faces[i]->displayPrimitive(I);
//         faces[i]->displayNormal(I);
    }
  }

#ifdef VISP_HAVE_OGRE
  if(useOgre)
    faces.displayOgre(cMo);
#endif
}

void
vpMbKltTracker::testTracking()
{
  unsigned int nbTotalPoints = 0;
  for (unsigned int i = 0; i < faces.size(); i += 1){
    if(faces[i]->isVisible()){
      nbTotalPoints += faces[i]->getNbPointsCur();
    }
  }

  if(nbTotalPoints < 10){
    std::cerr << "test tracking failed (too few points to realize a good tracking)." << std::endl;
    throw vpTrackingException(vpTrackingException::fatalError,
          "test tracking failed (too few points to realize a good tracking).");
  }
}

#endif //VISP_HAVE_OPENCV