Resolve "Merge doesn't delete already merged person from further evaluation"

There was an error, where a person, who was already deleted because they were merged with another, still got evaluated. During this evaluation, the person which got the index of the deleted one got processed, or a segmentation fault happened, when the deleted person was the last one.

This is fixed by setting mStatus to not only signal not being tracked, but also, already being merged away.

Steps to reproduce

This happens with trajectories, where:

1. The lower index is the traj that survives the merge
2. Both trajecories where already trackd at that frame
3. Both trajectories get retracked

(Note: The 3rd one could be annoying in using merge, since without retracking, no merging occurs; could be resolved with #261 )

So how to achieve that?

1. Use complete trajectory vs a fake one in the middle of the video (e.g. real Frame 0 - 300, fake 150 - 160)
2. Track both points without merge for a while and go back to the middle of the tracked trajectories
3. Set the retack below quality to 100 and use the color marker

One also probably needs to comment out the logic which disabled retracking if inefficient in Tracker::calcPrevFeaturePoints:

            /*
             * For retracking to occur, every point in the path from the last
             * recognized point to this point should have been tracked with higher qual.
             * This should eliminate cases in which wrong points are tracked confidently
             * and replace better ones, under the assumption we only get to a wrong point
             * due to a low-quality tracking earlier.
             */
            bool applyReTrack = reTrack;
            //            if(reTrack)
            //            {
            //                int dir = (frame - prevFrame); // direction of tracking - forward/backwards
            //                dir /= std::abs(dir);          // theoretically possible to omit MAX_STEP_TRACK frames
            //                constexpr int minQualReco = 90;
            //                for(int j = 0; person.trackPointExist(frame + j * dir) &&
            //                               person.trackPointAt(frame + j * dir).qual() < minQualReco;
            //                    ++j)
            //                {
            //                    if(person.trackPointAt(frame + j * dir).qual() < reQual)
            //                    {
            //                        applyReTrack = false;
            //                        break;
            //                    }
            //                }
            //            }
            if(person.trackPointExist(frame) && !applyReTrack)
            {
                continue;
            }

Closes #274 (closed)

src/tracker.cpp

@@ -777,7 +777,7 @@ int Tracker::insertFeaturePoints(int frame, size_t count, cv::Mat &img, int bord
 
     for(size_t i = 0; i < count; ++i)
     {
-        if(mStatus[i])
+        if(mStatus[i] == TrackStatus::Tracked)
         {
             v = Vec2F(mFeaturePoints.at(i).x, mFeaturePoints.at(i).y); // umwandlung nach TrackPoint bei "="
 
@@ -856,7 +856,8 @@ int Tracker::insertFeaturePoints(int frame, size_t count, cv::Mat &img, int bord
         }
         else
         {
-            if(v.x() >= dist && v.y() >= dist && v.x() <= img.cols - 1 - dist && v.y() <= img.rows - 1 - dist)
+            if(mStatus[i] == TrackStatus::NotTracked && v.x() >= dist && v.y() >= dist &&
+               v.x() <= img.cols - 1 - dist && v.y() <= img.rows - 1 - dist)
             {
                 debout << "Warning: Lost trajectory inside picture of person " << mPrevFeaturePointsIdx[i] + 1
                        << " at frame " << frame << "!" << std::endl;
@@ -877,12 +878,11 @@ int Tracker::insertFeaturePoints(int frame, size_t count, cv::Mat &img, int bord
  */
 bool Tracker::tryMergeTrajectories(const TrackPoint &v, size_t i, int frame)
 {
-    bool        found = false;
-    int         j;
+    bool        found   = false;
     const auto &persons = mPersonStorage.getPersons();
     const auto &person  = persons[mPrevFeaturePointsIdx[i]];
     // nach trajektorie suchen, mit der eine verschmelzung erfolgen koennte
-    for(j = 0; !found && j < static_cast<int>(mPersonStorage.nbPersons()); ++j) // ueber TrackPerson
+    for(int j = 0; !found && j < static_cast<int>(mPersonStorage.nbPersons()); ++j) // ueber TrackPerson
     {
         const auto &other = persons[j];
         if(j != mPrevFeaturePointsIdx[i] && other.trackPointExist(frame) &&
@@ -899,6 +899,7 @@ bool Tracker::tryMergeTrajectories(const TrackPoint &v, size_t i, int frame)
             {
                 int deleteIndex = mPersonStorage.merge(mPrevFeaturePointsIdx[i], j);
 
+                int idxOtherMerged = -1;
                 // shift index of feature points
                 for(size_t k = 0; k < mPrevFeaturePointsIdx.size(); ++k)
                 {
@@ -906,6 +907,15 @@ bool Tracker::tryMergeTrajectories(const TrackPoint &v, size_t i, int frame)
                     {
                         --mPrevFeaturePointsIdx[k];
                     }
+                    else if(mPrevFeaturePointsIdx[k] == deleteIndex)
+                    {
+                        idxOtherMerged = static_cast<int>(k);
+                    }
+                }
+                if(idxOtherMerged != -1)
+                {
+                    // set status to 2, so the already merged person is ignored/skipped
+                    mStatus[idxOtherMerged] = TrackStatus::Merged;
                 }
                 found = true;
             }
@@ -1142,7 +1152,8 @@ void Tracker::trackFeaturePointsLK(int level, bool adaptive)
             mTrackError[i]    = localTrackError[0] * 10.F / winSize;
 
         } while(adaptive && localStatus[0] == 0 && (l--) > 0);
-        mStatus[i] = localStatus[0];
+        // status from OpenCV: 0 -> not tracked, 1 -> tracked
+        mStatus[i] = localStatus[0] ? TrackStatus::Tracked : TrackStatus::NotTracked;
     }
 }
 
@@ -1230,7 +1241,7 @@ void Tracker::useBackgroundFilter(QList<int> &trjToDel, BackgroundFilter *bgFilt
 
         // Rahmen, in dem nicht vordergrund pflicht, insbesondere am rechten rand!!!! es wird gruenes von hand
         // angelegtes bounding rect roi genutzt
-        if((mStatus[i] == 1) && x >= MAX(margin, rect.x()) &&
+        if((mStatus[i] == TrackStatus::Tracked) && x >= MAX(margin, rect.x()) &&
            x <= MIN(mGrey.cols - 1 - 2 * bS - margin - 50, rect.x() + rect.width()) && y >= MAX(margin, rect.y()) &&
            y <= MIN(mGrey.rows - 1 - 2 * bS - margin, rect.y() + rect.height()))
         {
@@ -1279,8 +1290,8 @@ void Tracker::refineViaNearDarkPoint()
         // da in kontrastarmen regionen der angegebene fehler gering, aber das resultat haeufiger fehlerhaft ist
         // es waere daher schoen, wenn der fehler in abhaengigkeit von kontrast in umgebung skaliert wuerde
         // zb (max 0..255): normal 10..150 -> *1; klein 15..50 -> *3; gross 0..255 -> *.5
-        if((mTrackError[i] > MAX_TRACK_ERROR) && (mStatus[i] == 1) && x >= 0 && x < mGrey.cols && y >= 0 &&
-           y < mGrey.rows)
+        if((mTrackError[i] > MAX_TRACK_ERROR) && (mStatus[i] == TrackStatus::Tracked) && x >= 0 && x < mGrey.cols &&
+           y >= 0 && y < mGrey.rows)
         {
             int regionSize = myRound(
                 mMainWindow->getHeadSize(nullptr, mPrevFeaturePointsIdx[i], mPrevFrame) /