osrm-backend/plugins/map_matching.hpp

    /*
        open source routing machine
    Copyright (C) Dennis Luxen, others 2010

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU AFFERO General Public License as published by
the Free Software Foundation; either version 3 of the License, or
any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
or see http://www.gnu.org/licenses/agpl.txt.
 */

#ifndef MAP_MATCHING_PLUGIN_H
#define MAP_MATCHING_PLUGIN_H

#include "plugin_base.hpp"

#include "../algorithms/bayes_classifier.hpp"
#include "../algorithms/object_encoder.hpp"
#include "../util/integer_range.hpp"
#include "../data_structures/search_engine.hpp"
#include "../routing_algorithms/map_matching.hpp"
#include "../util/compute_angle.hpp"
#include "../util/simple_logger.hpp"
#include "../util/string_util.hpp"
#include "../descriptors/descriptor_base.hpp"
#include "../descriptors/gpx_descriptor.hpp"
#include "../descriptors/json_descriptor.hpp"

#include <cstdlib>

#include <algorithm>
#include <memory>
#include <string>
#include <vector>

template <class DataFacadeT> class MapMatchingPlugin : public BasePlugin
{
  private:
    std::unordered_map<std::string, unsigned> descriptor_table;
    std::shared_ptr<SearchEngine<DataFacadeT>> search_engine_ptr;

    using ClassifierT = BayesClassifier<LaplaceDistribution, LaplaceDistribution, double>;
    using TraceClassification = ClassifierT::ClassificationT;

  public:
    MapMatchingPlugin(DataFacadeT *facade)
    : descriptor_string("match")
    , facade(facade)
    // the values where derived from fitting a laplace distribution
    // to the values of manually classified traces
    , classifier(LaplaceDistribution(0.0057154021891018675, 0.020294704891166186),
                 LaplaceDistribution(0.11467696742821254, 0.49918444000368756),
                 0.7977883096366508) // valid apriori probability
    {
        descriptor_table.emplace("json", 0);
        search_engine_ptr = std::make_shared<SearchEngine<DataFacadeT>>(facade);
    }

    virtual ~MapMatchingPlugin() { search_engine_ptr.reset(); }

    const std::string GetDescriptor() const final { return descriptor_string; }

    TraceClassification classify(float trace_length, float matched_length, int removed_points) const
    {
        double distance_feature = -std::log(trace_length) + std::log(matched_length);

        // matched to the same point
        if (!std::isfinite(distance_feature))
        {
            return std::make_pair(ClassifierT::ClassLabel::NEGATIVE, 1.0);
        }

        auto label_with_confidence =  classifier.classify(distance_feature);

        // "second stage classifier": if we need to remove points there is something fishy
        if (removed_points > 0)
        {
            return std::make_pair(ClassifierT::ClassLabel::NEGATIVE, 1.0);
        }

        return label_with_confidence;
    }

    bool get_candiates(const std::vector<FixedPointCoordinate>& input_coords, std::vector<double>& sub_trace_lengths, Matching::CandidateLists& candidates_lists)
    {
        double last_distance = coordinate_calculation::great_circle_distance(
            input_coords[0],
            input_coords[1]);
        sub_trace_lengths.resize(input_coords.size());
        sub_trace_lengths[0] = 0;
        for (const auto current_coordinate : osrm::irange<std::size_t>(0, input_coords.size()))
        {
            bool allow_uturn = false;
            if (0 < current_coordinate)
            {
                last_distance = coordinate_calculation::great_circle_distance(
                    input_coords[current_coordinate - 1],
                    input_coords[current_coordinate]);
                sub_trace_lengths[current_coordinate] += sub_trace_lengths[current_coordinate-1] + last_distance;
            }

            if (input_coords.size()-1 > current_coordinate && 0 < current_coordinate)
            {
                double turn_angle = ComputeAngle::OfThreeFixedPointCoordinates(
                                                    input_coords[current_coordinate-1],
                                                    input_coords[current_coordinate],
                                                    input_coords[current_coordinate+1]);

                // sharp turns indicate a possible uturn
                if (turn_angle < 100.0 || turn_angle > 260.0)
                {
                    allow_uturn = true;
                }
            }

            std::vector<std::pair<PhantomNode, double>> candidates;
            if (!facade->IncrementalFindPhantomNodeForCoordinateWithMaxDistance(
                    input_coords[current_coordinate],
                    candidates,
                    last_distance/2.0,
                    5,
                    Matching::max_number_of_candidates))
            {
                return false;
            }

            if (allow_uturn)
            {
                candidates_lists.push_back(candidates);
            }
            else
            {
                unsigned compact_size = candidates.size();
                for (const auto i : osrm::irange(0u, compact_size))
                {
                    // Split edge if it is bidirectional and append reverse direction to end of list
                    if (candidates[i].first.forward_node_id != SPECIAL_NODEID
                     && candidates[i].first.reverse_node_id != SPECIAL_NODEID)
                    {
                        PhantomNode reverse_node(candidates[i].first);
                        reverse_node.forward_node_id = SPECIAL_NODEID;
                        candidates.push_back(std::make_pair(reverse_node, candidates[i].second));

                        candidates[i].first.reverse_node_id = SPECIAL_NODEID;
                    }
                }
                candidates_lists.push_back(candidates);
            }

        }

        return true;
    }

    int HandleRequest(const RouteParameters &route_parameters, osrm::json::Object &json_result) final
    {
        // check number of parameters
        if (!check_all_coordinates(route_parameters.coordinates))
        {
            return 400;
        }

        std::vector<double> sub_trace_lengths;
        Matching::CandidateLists candidates_lists;
        const auto& input_coords = route_parameters.coordinates;
        const auto& input_timestamps = route_parameters.timestamps;
        if (input_timestamps.size() > 0 && input_coords.size() != input_timestamps.size())
        {
            return 400;
        }
        bool found_candidates = get_candiates(input_coords, sub_trace_lengths, candidates_lists);
        if (!found_candidates)
        {
            return 400;
        }

        // call the actual map matching
        osrm::json::Object debug_info;
        Matching::SubMatchingList sub_matchings;
        search_engine_ptr->map_matching(candidates_lists, input_coords, input_timestamps, sub_matchings, debug_info);

        if (1 > sub_matchings.size())
        {
            return 400;
        }

        osrm::json::Array matchings;
        for (auto& sub : sub_matchings)
        {
            // classify result
            double trace_length = sub_trace_lengths[sub.indices.back()] - sub_trace_lengths[sub.indices.front()];
            TraceClassification classification = classify(trace_length,
                                                          sub.length,
                                                          (sub.indices.back() - sub.indices.front() + 1) - sub.nodes.size());
            if (classification.first == ClassifierT::ClassLabel::POSITIVE)
            {
                sub.confidence = classification.second;
            }
            else
            {
                sub.confidence = 1-classification.second;
            }

            BOOST_ASSERT(sub.nodes.size() > 1);

            // FIXME this is a pretty bad hack. Geometries should obtained directly
            // from map_matching.
            // run shortest path routing to obtain geometry
            InternalRouteResult raw_route;
            PhantomNodes current_phantom_node_pair;
            for (unsigned i = 0; i < sub.nodes.size() - 1; ++i)
            {
                current_phantom_node_pair.source_phantom = sub.nodes[i];
                current_phantom_node_pair.target_phantom = sub.nodes[i + 1];
                raw_route.segment_end_coordinates.emplace_back(current_phantom_node_pair);
            }
            search_engine_ptr->shortest_path(
                raw_route.segment_end_coordinates,
                std::vector<bool>(raw_route.segment_end_coordinates.size(), true),
                raw_route);


            DescriptorConfig descriptor_config;

            auto iter = descriptor_table.find(route_parameters.output_format);
            unsigned descriptor_type = (iter != descriptor_table.end() ? iter->second : 0);

            descriptor_config.zoom_level = route_parameters.zoom_level;
            descriptor_config.instructions = false;
            descriptor_config.geometry = route_parameters.geometry;
            descriptor_config.encode_geometry = route_parameters.compression;

            std::shared_ptr<BaseDescriptor<DataFacadeT>> descriptor;
            switch (descriptor_type)
            {
            // case 0:
            //     descriptor = std::make_shared<JSONDescriptor<DataFacadeT>>();
            //     break;
            case 1:
                descriptor = std::make_shared<GPXDescriptor<DataFacadeT>>(facade);
                break;
            // case 2:
            //      descriptor = std::make_shared<GEOJSONDescriptor<DataFacadeT>>();
            //      break;
            default:
                descriptor = std::make_shared<JSONDescriptor<DataFacadeT>>(facade);
                break;
            }

            osrm::json::Object temp_result;
            descriptor->SetConfig(descriptor_config);
            descriptor->Run(raw_route, temp_result);

            osrm::json::Array indices;
            for (const auto& i : sub.indices)
            {
                indices.values.emplace_back(i);
            }

            osrm::json::Object subtrace;
            subtrace.values["geometry"] = temp_result.values["route_geometry"];
            subtrace.values["confidence"] = sub.confidence;
            subtrace.values["indices"] = indices;
            subtrace.values["matched_points"] = temp_result.values["via_points"];

            matchings.values.push_back(subtrace);
        }

        json_result.values["debug"] = debug_info;
        json_result.values["matchings"] = matchings;

        return 200;
    }

  private:
    std::string descriptor_string;
    DataFacadeT *facade;
    ClassifierT classifier;
};

#endif /* MAP_MATCHING_PLUGIN_H */