osrm-backend/plugins/map_matching.hpp

/*

Copyright (c) 2015, Project OSRM contributors
All rights reserved.

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are permitted provided that the following conditions are met:

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list of conditions and the following disclaimer in the documentation and/or
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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*/

#ifndef MAP_MATCHING_PLUGIN_HPP
#define MAP_MATCHING_PLUGIN_HPP

#include "plugin_base.hpp"

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

#include <cstdlib>

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

template <class DataFacadeT> class MapMatchingPlugin : public BasePlugin
{
  private:
    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
    {
        search_engine_ptr = std::make_shared<SearchEngine<DataFacadeT>>(facade);
    }

    virtual ~MapMatchingPlugin() { }

    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 getCandiates(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;
    }

    osrm::json::Object submatchingToJSON(const Matching::SubMatching& sub, const RouteParameters& route_parameters, const InternalRouteResult& raw_route)
    {
        osrm::json::Object subtrace;

        subtrace.values["confidence"] = sub.confidence;

        if (route_parameters.geometry)
        {
            DescriptionFactory factory;
            FixedPointCoordinate current_coordinate;
            factory.SetStartSegment(
                raw_route.segment_end_coordinates.front().source_phantom,
                raw_route.source_traversed_in_reverse.front());
            for (const auto i : osrm::irange<std::size_t>(0, raw_route.unpacked_path_segments.size()))
            {
                for (const PathData &path_data : raw_route.unpacked_path_segments[i])
                {
                    current_coordinate = facade->GetCoordinateOfNode(path_data.node);
                    factory.AppendSegment(current_coordinate, path_data);
                }
                factory.SetEndSegment(raw_route.segment_end_coordinates[i].target_phantom,
                                      raw_route.target_traversed_in_reverse[i],
                                      raw_route.is_via_leg(i));
            }
            subtrace.values["geometry"] = factory.AppendGeometryString(route_parameters.compression);
        }

        subtrace.values["indices"] = osrm::json::make_array(sub.indices);


        osrm::json::Array points;
        for (const auto& node : sub.nodes)
        {
            points.values.emplace_back(osrm::json::make_array(node.location.lat / COORDINATE_PRECISION,
                                                              node.location.lon / COORDINATE_PRECISION));
        }
        subtrace.values["matched_points"] = points;

        return subtrace;
    }

    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 = getCandiates(input_coords, sub_trace_lengths, candidates_lists);
        if (!found_candidates)
        {
            return 400;
        }

        // call the actual map matching
        if (osrm::json::Logger::get())
            osrm::json::Logger::get()->initialize("matching");
        Matching::SubMatchingList sub_matchings;
        search_engine_ptr->map_matching(candidates_lists, input_coords, input_timestamps, sub_matchings);

        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 we only run this to obtain the geometry
            // The clean way would be to get this directly from the map matching plugin
            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);

            matchings.values.emplace_back(submatchingToJSON(sub, route_parameters, raw_route));
        }

        if (osrm::json::Logger::get())
            osrm::json::Logger::get()->render("matching", json_result);
        json_result.values["matchings"] = matchings;

        return 200;
    }

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

#endif /* MAP_MATCHING_HPP */