Method TrackingUsingNormFlow

src/core/event_preprocessing.cpp:623–803

* EventLineTracking */

 * EventLineTracking
 */
void EventLineTracking::TrackingUsingNormFlow(const EventNormFlow::NormFlowPack::Ptr &nfPack) {
    // sort norm flow data
    std::list<NormFlow::Ptr> nfs = nfPack->TemporallySortedNormFlows();

#define SHOW_DETAILS 0

    std::set<EventLine::Ptr> linesCandidates;
    std::map<EventLine::Ptr, std::list<NormFlow::Ptr>> lineWithNFs;
    // std::map<EventLine::Ptr, LineParamUpdate::Ptr> lineParamUpdate;
    auto MergeLine1ToLine2 = [&linesCandidates, &lineWithNFs](const EventLine::Ptr &line1,
                                                              const EventLine::Ptr &line2) {
        const auto &nfsOfLine1 = lineWithNFs[line1];
        auto &nfsOfLine2 = lineWithNFs[line2];
        nfsOfLine2.insert(nfsOfLine2.end(), nfsOfLine1.begin(), nfsOfLine1.end());
        linesCandidates.erase(line1);
        lineWithNFs.erase(line1);
    };

    double lastTime = nfs.front()->timestamp;
    for (const auto &nf : nfs) {
        // compute the delta time, update last time stamp
        double dt = nf->timestamp - lastTime;
        const double decay = std::exp(-nf->nfNorm * dt);
        lastTime = nf->timestamp;

        // spdlog::info("p: ({}, {}), t: {:.5f} (sec), dt: {:.3f}, nf: ({:.3f}, {:.3f})", nf->p(0),
        //              nf->p(1), nf->timestamp, dt, nf->nf(0), nf->nf(1));

        EventLine::Ptr ml = nullptr;
        for (auto &el : linesCandidates) {
            // apply the decay
            el->activity *= decay;
            el->timestamp = nf->timestamp;

            // association
            const double dist = std::abs(el->PointToLine(nf->p.cast<double>()));
            const double dirDiffCos = el->DirectionDifferenceCos(nf->nfDir);
            // too far
            if (dist > P2L_DISTANCE_THD) {
#if SHOW_DETAILS
                spdlog::warn("distance too far!!! Jump it!!!");
#endif
                continue;
            }
            // not same direction
            if (dirDiffCos < P2L_ORIENTATION_THD) {
#if SHOW_DETAILS
                spdlog::warn("orientation difference too large!!! Jump it!!!");
#endif
                continue;
            }
            // find the line whose activity is the largest, i.e., matched (associated) line
            if (ml == nullptr) {
                ml = el;
            } else {
                if (ml->activity < el->activity) {
                    ml = el;
                }