Method validate_candidates

src/PLPSLAM/module/loop_detector.cc:129–236

        }

        bool loop_detector::validate_candidates()
        {
            // disallow the removal of the candidates
            for (const auto candidate : loop_candidates_to_validate_)
            {
                candidate->set_not_to_be_erased();
            }

            // [1] for each of the candidates, estimate and validate the Sim3 between it and the current keyframe using the observed landmarks
            //    then, select ONE candidate

            const bool candidate_is_found = select_loop_candidate_via_Sim3(loop_candidates_to_validate_, selected_candidate_,
                                                                           g2o_Sim3_world_to_curr_, curr_match_lms_observed_in_cand_);

            Sim3_world_to_curr_ = util::converter::to_eigen_mat(g2o_Sim3_world_to_curr_);

            if (!candidate_is_found)
            {
                for (const auto loop_candidate : loop_candidates_to_validate_)
                {
                    loop_candidate->set_to_be_erased();
                }
                return false;
            }

            spdlog::debug("detect loop candidate via Sim3 estimation: keyframe {} - keyframe {}", selected_candidate_->id_, cur_keyfrm_->id_);

            // [2] reproject the landmarks observed in covisibilities of the selected candidate to the current keyframe,
            //    then acquire the extra 2D-3D matches

            // matches between the keypoints in the current and the landmarks observed in the covisibilities of the selected candidate
            curr_match_lms_observed_in_cand_covis_.clear();

            auto cand_covisibilities = selected_candidate_->graph_node_->get_covisibilities();
            cand_covisibilities.push_back(selected_candidate_);

            // acquire all of the landmarks observed in the covisibilities of the candidate
            // check the already inserted landmarks
            std::unordered_set<data::landmark *> already_inserted;
            for (const auto covisibility : cand_covisibilities)
            {
                const auto lms_in_covisibility = covisibility->get_landmarks();
                for (const auto lm : lms_in_covisibility)
                {
                    if (!lm)
                    {
                        continue;
                    }
                    if (lm->will_be_erased())
                    {
                        continue;
                    }

                    if (already_inserted.count(lm))
                    {
                        continue;
                    }
                    curr_match_lms_observed_in_cand_covis_.push_back(lm);