void MapPoint::ComputeDistinctiveDescriptors()
{
// Retrieve all observed descriptors
vector<cv::Mat> vDescriptors;
map<KeyFrame*,size_t> observations;
{
boost::mutex::scoped_lock lock1(mMutexFeatures);
if(mbBad)
return;
observations=mObservations;
}
if(observations.empty())
return;
vDescriptors.reserve(observations.size());
for(map<KeyFrame*,size_t>::iterator mit=observations.begin(), mend=observations.end(); mit!=mend; mit++)
{
KeyFrame* pKF = mit->first;
if(!pKF->isBad())
vDescriptors.push_back(pKF->GetDescriptor(mit->second));
}
if(vDescriptors.empty())
return;
// Compute distances between them
const size_t N = vDescriptors.size();
float Distances[N][N];
for(size_t i=0;i<N;i++)
{
Distances[i][i]=0;
for(size_t j=i+1;j<N;j++)
{
int distij = ORBmatcher::DescriptorDistance(vDescriptors[i],vDescriptors[j]);
Distances[i][j]=distij;
Distances[j][i]=distij;
}
}
// Take the descriptor with least median distance to the rest
int BestMedian = INT_MAX;
int BestIdx = 0;
for(size_t i=0;i<N;i++)
{
vector<int> vDists(Distances[i],Distances[i]+N);
sort(vDists.begin(),vDists.end());
int median = vDists[0.5*(N-1)];
if(median<BestMedian)
{
BestMedian = median;
BestIdx = i;
}
}
{
boost::mutex::scoped_lock lock(mMutexFeatures);
mDescriptor = vDescriptors[BestIdx].clone();
}
}
bool LoopClosing::DetectLoop()
{
{
boost::mutex::scoped_lock lock(mMutexLoopQueue);
mpCurrentKF = mlpLoopKeyFrameQueue.front();
mlpLoopKeyFrameQueue.pop_front();
// Avoid that a keyframe can be erased while it is being process by this thread
mpCurrentKF->SetNotErase();
}
//If the map contains less than 10 KF or less than 10KF have passed from last loop detection
if(mpCurrentKF->mnId<mLastLoopKFid+10)
{
mpKeyFrameDB->add(mpCurrentKF);
mpCurrentKF->SetErase();
return false;
}
// Compute reference BoW similarity score
// This is the lowest score to a connected keyframe in the covisibility graph
// We will impose loop candidates to have a higher similarity than this
vector<KeyFrame*> vpConnectedKeyFrames = mpCurrentKF->GetVectorCovisibleKeyFrames();
DBoW2::BowVector CurrentBowVec = mpCurrentKF->GetBowVector();
float minScore = 1;
for(size_t i=0; i<vpConnectedKeyFrames.size(); i++)
{
KeyFrame* pKF = vpConnectedKeyFrames[i];
if(pKF->isBad())
continue;
DBoW2::BowVector BowVec = pKF->GetBowVector();
float score = mpORBVocabulary->score(CurrentBowVec, BowVec);
if(score<minScore)
minScore = score;
}
// Query the database imposing the minimum score
vector<KeyFrame*> vpCandidateKFs = mpKeyFrameDB->DetectLoopCandidates(mpCurrentKF, minScore);
// If there are no loop candidates, just add new keyframe and return false
if(vpCandidateKFs.empty())
{
mpKeyFrameDB->add(mpCurrentKF);
mvConsistentGroups.clear();
mpCurrentKF->SetErase();
return false;
}
// For each loop candidate check consistency with previous loop candidates
// Each candidate expands a covisibility group (keyframes connected to the loop candidate in the covisibility graph)
// A group is consistent with a previous group if they share at least a keyframe
// We must detect a consistent loop in several consecutive keyframe to accept it
mvpEnoughConsistentCandidates.clear();
vector<ConsistentGroup> vCurrentConsistentGroups;
vector<bool> vbConsistentGroup(mvConsistentGroups.size(),false);
for(size_t i=0, iend=vpCandidateKFs.size(); i<iend; i++)
{
KeyFrame* pCandidateKF = vpCandidateKFs[i];
set<KeyFrame*> spCandidateGroup = pCandidateKF->GetConnectedKeyFrames();
spCandidateGroup.insert(pCandidateKF);
bool bEnoughConsistent = false;
bool bConsistentForSomeGroup = false;
for(size_t iG=0, iendG=mvConsistentGroups.size(); iG<iendG; iG++)
{
set<KeyFrame*> sPreviousGroup = mvConsistentGroups[iG].first;
bool bConsistent = false;
for(set<KeyFrame*>::iterator sit=spCandidateGroup.begin(), send=spCandidateGroup.end(); sit!=send;sit++)
{
if(sPreviousGroup.count(*sit))
{
bConsistent=true;
bConsistentForSomeGroup=true;
break;
}
}
if(bConsistent)
{
int nPreviousConsistency = mvConsistentGroups[iG].second;
int nCurrentConsistency = nPreviousConsistency + 1;
if(!vbConsistentGroup[iG])
{
ConsistentGroup cg = make_pair(spCandidateGroup,nCurrentConsistency);
vCurrentConsistentGroups.push_back(cg);
vbConsistentGroup[iG]=true; //this avoid to include the same group more than once
}
if(nCurrentConsistency>=mnCovisibilityConsistencyTh && !bEnoughConsistent)
{
mvpEnoughConsistentCandidates.push_back(pCandidateKF);
bEnoughConsistent=true; //this avoid to insert the same candidate more than once
}
}
}
// If the group is not consistent with any previous group insert with consistency counter set to zero
if(!bConsistentForSomeGroup)
{
ConsistentGroup cg = make_pair(spCandidateGroup,0);
vCurrentConsistentGroups.push_back(cg);
}
}
// Update Covisibility Consistent Groups
mvConsistentGroups = vCurrentConsistentGroups;
// Add Current Keyframe to database
mpKeyFrameDB->add(mpCurrentKF);
if(mvpEnoughConsistentCandidates.empty())
{
mpCurrentKF->SetErase();
return false;
}
else
{
return true;
}
mpCurrentKF->SetErase();
return false;
}
void LocalMapping::SearchInNeighbors()
{
// Retrieve neighbor keyframes
vector<KeyFrame*> vpNeighKFs = mpCurrentKeyFrame->GetBestCovisibilityKeyFrames(20);
vector<KeyFrame*> vpTargetKFs;
for(vector<KeyFrame*>::iterator vit=vpNeighKFs.begin(), vend=vpNeighKFs.end(); vit!=vend; vit++)
{
KeyFrame* pKFi = *vit;
if(pKFi->isBad() || pKFi->mnFuseTargetForKF == mpCurrentKeyFrame->mnId)
continue;
vpTargetKFs.push_back(pKFi);
pKFi->mnFuseTargetForKF = mpCurrentKeyFrame->mnId;
// Extend to some second neighbors
vector<KeyFrame*> vpSecondNeighKFs = pKFi->GetBestCovisibilityKeyFrames(5);
for(vector<KeyFrame*>::iterator vit2=vpSecondNeighKFs.begin(), vend2=vpSecondNeighKFs.end(); vit2!=vend2; vit2++)
{
KeyFrame* pKFi2 = *vit2;
if(pKFi2->isBad() || pKFi2->mnFuseTargetForKF==mpCurrentKeyFrame->mnId || pKFi2->mnId==mpCurrentKeyFrame->mnId)
continue;
vpTargetKFs.push_back(pKFi2);
}
}
// Search matches by projection from current KF in target KFs
ORBmatcher matcher(0.6);
vector<MapPoint*> vpMapPointMatches = mpCurrentKeyFrame->GetMapPointMatches();
for(vector<KeyFrame*>::iterator vit=vpTargetKFs.begin(), vend=vpTargetKFs.end(); vit!=vend; vit++)
{
KeyFrame* pKFi = *vit;
matcher.Fuse(pKFi,vpMapPointMatches);
}
// Search matches by projection from target KFs in current KF
vector<MapPoint*> vpFuseCandidates;
vpFuseCandidates.reserve(vpTargetKFs.size()*vpMapPointMatches.size());
for(vector<KeyFrame*>::iterator vitKF=vpTargetKFs.begin(), vendKF=vpTargetKFs.end(); vitKF!=vendKF; vitKF++)
{
KeyFrame* pKFi = *vitKF;
vector<MapPoint*> vpMapPointsKFi = pKFi->GetMapPointMatches();
for(vector<MapPoint*>::iterator vitMP=vpMapPointsKFi.begin(), vendMP=vpMapPointsKFi.end(); vitMP!=vendMP; vitMP++)
{
MapPoint* pMP = *vitMP;
if(!pMP)
continue;
if(pMP->isBad() || pMP->mnFuseCandidateForKF == mpCurrentKeyFrame->mnId)
continue;
pMP->mnFuseCandidateForKF = mpCurrentKeyFrame->mnId;
vpFuseCandidates.push_back(pMP);
}
}
matcher.Fuse(mpCurrentKeyFrame,vpFuseCandidates);
// Update points
vpMapPointMatches = mpCurrentKeyFrame->GetMapPointMatches();
for(size_t i=0, iend=vpMapPointMatches.size(); i<iend; i++)
{
MapPoint* pMP=vpMapPointMatches[i];
if(pMP)
{
if(!pMP->isBad())
{
pMP->ComputeDistinctiveDescriptors();
pMP->UpdateNormalAndDepth();
}
}
}
// Update connections in covisibility graph
mpCurrentKeyFrame->UpdateConnections();
}
bool LoopClosing::ComputeSim3()
{
// For each consistent loop candidate we try to compute a Sim3
const int nInitialCandidates = mvpEnoughConsistentCandidates.size();
// We compute first ORB matches for each candidate
// If enough matches are found, we setup a Sim3Solver
ORBmatcher matcher(0.75,true);
vector<Sim3Solver*> vpSim3Solvers;
vpSim3Solvers.resize(nInitialCandidates);
vector<vector<MapPoint*> > vvpMapPointMatches;
vvpMapPointMatches.resize(nInitialCandidates);
vector<bool> vbDiscarded;
vbDiscarded.resize(nInitialCandidates);
int nCandidates=0; //candidates with enough matches
for(int i=0; i<nInitialCandidates; i++)
{
KeyFrame* pKF = mvpEnoughConsistentCandidates[i];
// avoid that local mapping erase it while it is being processed in this thread
pKF->SetNotErase();
if(pKF->isBad())
{
vbDiscarded[i] = true;
continue;
}
int nmatches = matcher.SearchByBoW(mpCurrentKF,pKF,vvpMapPointMatches[i]);
if(nmatches<20)
{
vbDiscarded[i] = true;
continue;
}
else
{
Sim3Solver* pSolver = new Sim3Solver(mpCurrentKF,pKF,vvpMapPointMatches[i]);
pSolver->SetRansacParameters(0.99,20,300);
vpSim3Solvers[i] = pSolver;
}
nCandidates++;
}
bool bMatch = false;
// Perform alternatively RANSAC iterations for each candidate
// until one is succesful or all fail
while(nCandidates>0 && !bMatch)
{
for(int i=0; i<nInitialCandidates; i++)
{
if(vbDiscarded[i])
continue;
KeyFrame* pKF = mvpEnoughConsistentCandidates[i];
// Perform 5 Ransac Iterations
vector<bool> vbInliers;
int nInliers;
bool bNoMore;
Sim3Solver* pSolver = vpSim3Solvers[i];
cv::Mat Scm = pSolver->iterate(5,bNoMore,vbInliers,nInliers);
// If Ransac reachs max. iterations discard keyframe
if(bNoMore)
{
vbDiscarded[i]=true;
nCandidates--;
}
// If RANSAC returns a Sim3, perform a guided matching and optimize with all correspondences
if(!Scm.empty())
{
vector<MapPoint*> vpMapPointMatches(vvpMapPointMatches[i].size(), static_cast<MapPoint*>(NULL));
for(size_t j=0, jend=vbInliers.size(); j<jend; j++)
{
if(vbInliers[j])
vpMapPointMatches[j]=vvpMapPointMatches[i][j];
}
cv::Mat R = pSolver->GetEstimatedRotation();
cv::Mat t = pSolver->GetEstimatedTranslation();
const float s = pSolver->GetEstimatedScale();
matcher.SearchBySim3(mpCurrentKF,pKF,vpMapPointMatches,s,R,t,7.5);
g2o::Sim3 gScm(Converter::toMatrix3d(R),Converter::toVector3d(t),s);
const int nInliers = Optimizer::OptimizeSim3(mpCurrentKF, pKF, vpMapPointMatches, gScm, 10);
// If optimization is succesful stop ransacs and continue
if(nInliers>=20)
{
bMatch = true;
mpMatchedKF = pKF;
g2o::Sim3 gSmw(Converter::toMatrix3d(pKF->GetRotation()),Converter::toVector3d(pKF->GetTranslation()),1.0);
mg2oScw = gScm*gSmw;
mScw = Converter::toCvMat(mg2oScw);
mvpCurrentMatchedPoints = vpMapPointMatches;
break;
}
}
}
}
if(!bMatch)
{
for(int i=0; i<nInitialCandidates; i++)
mvpEnoughConsistentCandidates[i]->SetErase();
mpCurrentKF->SetErase();
return false;
}
// Retrieve MapPoints seen in Loop Keyframe and neighbors
vector<KeyFrame*> vpLoopConnectedKFs = mpMatchedKF->GetVectorCovisibleKeyFrames();
vpLoopConnectedKFs.push_back(mpMatchedKF);
mvpLoopMapPoints.clear();
for(vector<KeyFrame*>::iterator vit=vpLoopConnectedKFs.begin(); vit!=vpLoopConnectedKFs.end(); vit++)
{
KeyFrame* pKF = *vit;
vector<MapPoint*> vpMapPoints = pKF->GetMapPointMatches();
for(size_t i=0, iend=vpMapPoints.size(); i<iend; i++)
{
MapPoint* pMP = vpMapPoints[i];
if(pMP)
{
if(!pMP->isBad() && pMP->mnLoopPointForKF!=mpCurrentKF->mnId)
{
mvpLoopMapPoints.push_back(pMP);
pMP->mnLoopPointForKF=mpCurrentKF->mnId;
}
}
}
}
// Find more matches projecting with the computed Sim3
matcher.SearchByProjection(mpCurrentKF, mScw, mvpLoopMapPoints, mvpCurrentMatchedPoints,10);
// If enough matches accept Loop
int nTotalMatches = 0;
for(size_t i=0; i<mvpCurrentMatchedPoints.size(); i++)
{
if(mvpCurrentMatchedPoints[i])
nTotalMatches++;
}
if(nTotalMatches>=40)
{
for(int i=0; i<nInitialCandidates; i++)
if(mvpEnoughConsistentCandidates[i]!=mpMatchedKF)
mvpEnoughConsistentCandidates[i]->SetErase();
return true;
}
else
{
for(int i=0; i<nInitialCandidates; i++)
mvpEnoughConsistentCandidates[i]->SetErase();
mpCurrentKF->SetErase();
return false;
}
}
void KeyFrame::SetBadFlag()
{
{
boost::mutex::scoped_lock lock(mMutexConnections);
if(mnId==0)
return;
else if(mbNotErase)
{
mbToBeErased = true;
return;
}
}
for(map<KeyFrame*,int>::iterator mit = mConnectedKeyFrameWeights.begin(), mend=mConnectedKeyFrameWeights.end(); mit!=mend; mit++)
mit->first->EraseConnection(this);
for(size_t i=0; i<mvpMapPoints.size(); i++)
if(mvpMapPoints[i])
mvpMapPoints[i]->EraseObservation(this);
{
boost::mutex::scoped_lock lock(mMutexConnections);
boost::mutex::scoped_lock lock1(mMutexFeatures);
mConnectedKeyFrameWeights.clear();
mvpOrderedConnectedKeyFrames.clear();
// Update Spanning Tree
set<KeyFrame*> sParentCandidates;
sParentCandidates.insert(mpParent);
// Assign at each iteration one children with a parent (the pair with highest covisibility weight)
// Include that children as new parent candidate for the rest
while(!mspChildrens.empty())
{
bool bContinue = false;
int max = -1;
KeyFrame* pC;
KeyFrame* pP;
for(set<KeyFrame*>::iterator sit=mspChildrens.begin(), send=mspChildrens.end(); sit!=send; sit++)
{
KeyFrame* pKF = *sit;
if(pKF->isBad())
continue;
// Check if a parent candidate is connected to the keyframe
vector<KeyFrame*> vpConnected = pKF->GetVectorCovisibleKeyFrames();
for(size_t i=0, iend=vpConnected.size(); i<iend; i++)
{
for(set<KeyFrame*>::iterator spcit=sParentCandidates.begin(), spcend=sParentCandidates.end(); spcit!=spcend; spcit++)
{
if(vpConnected[i]->mnId == (*spcit)->mnId)
{
int w = pKF->GetWeight(vpConnected[i]);
if(w>max)
{
pC = pKF;
pP = vpConnected[i];
max = w;
bContinue = true;
}
}
}
}
}
if(bContinue)
{
pC->ChangeParent(pP);
sParentCandidates.insert(pC);
mspChildrens.erase(pC);
}
else
break;
}
// If a children has no covisibility links with any parent candidate, assign to the original parent of this KF
if(!mspChildrens.empty())
for(set<KeyFrame*>::iterator sit=mspChildrens.begin(); sit!=mspChildrens.end(); sit++)
{
(*sit)->ChangeParent(mpParent);
}
mpParent->EraseChild(this);
mbBad = true;
}
mpMap->EraseKeyFrame(this);
mpKeyFrameDB->erase(this);
}
