Method DetectLoopCandidates

src/KeyFrameDatabase.cc:100–226

}

vector<KeyFrame*> KeyFrameDatabase::DetectLoopCandidates(KeyFrame* pKF, float minScore)
{
    set<KeyFrame*> spConnectedKeyFrames = pKF->GetConnectedKeyFrames();
    list<KeyFrame*> lKFsSharingWords;

    // Search all keyframes that share a word with current keyframes
    // Discard keyframes connected to the query keyframe
    {
        unique_lock<mutex> lock(mMutex);

        for(DBoW2::BowVector::const_iterator vit=pKF->mBowVec.begin(), vend=pKF->mBowVec.end(); vit != vend; vit++)
        {
            list<KeyFrame*> &lKFs =   mvInvertedFile[vit->first];

            for(list<KeyFrame*>::iterator lit=lKFs.begin(), lend= lKFs.end(); lit!=lend; lit++)
            {
                KeyFrame* pKFi=*lit;
                if(pKFi->GetMap()==pKF->GetMap()) // For consider a loop candidate it a candidate it must be in the same map
                {
                    if(pKFi->mnLoopQuery!=pKF->mnId)
                    {
                        pKFi->mnLoopWords=0;
                        if(!spConnectedKeyFrames.count(pKFi))
                        {
                            pKFi->mnLoopQuery=pKF->mnId;
                            lKFsSharingWords.push_back(pKFi);
                        }
                    }
                    pKFi->mnLoopWords++;
                }


            }
        }
    }

    if(lKFsSharingWords.empty())
        return vector<KeyFrame*>();

    list<pair<float,KeyFrame*> > lScoreAndMatch;

    // Only compare against those keyframes that share enough words
    int maxCommonWords=0;
    for(list<KeyFrame*>::iterator lit=lKFsSharingWords.begin(), lend= lKFsSharingWords.end(); lit!=lend; lit++)
    {
        if((*lit)->mnLoopWords>maxCommonWords)
            maxCommonWords=(*lit)->mnLoopWords;
    }

    int minCommonWords = maxCommonWords*0.8f;

    int nscores=0;

    // Compute similarity score. Retain the matches whose score is higher than minScore
    for(list<KeyFrame*>::iterator lit=lKFsSharingWords.begin(), lend= lKFsSharingWords.end(); lit!=lend; lit++)
    {
        KeyFrame* pKFi = *lit;