public MapMatcher(List <T> data, Func <T, DirectedRoad> dataToRoad, MapMatcherParameters parameters, bool useSearchGrid = true, BoundingBox boundingBox = null)
{
// Initialize parameters
Parameters = parameters;
//Build graph
_dataByRoadId = new Dictionary <string, T>();
var graph = new RoadGraph();
foreach (var datum in data)
{
var road = dataToRoad(datum);
graph.AddRoad(road);
_dataByRoadId[road.Squid] = datum;
}
Graph = graph;
// Compute search grid (for accessing nearby roads)
if (useSearchGrid)
{
// Compute bounding box if not given
if (boundingBox == null)
{
boundingBox = graph.Nodes.Values.GetBoundingBox();
}
SearchGrid = SearchGridFactory.ComputeSearchGrid(graph, parameters.NearbyRoadsThreshold, boundingBox);
}
// Initialize state
State = MapMatchState.InitialState();
}
public Transition(double onRoadDistanceInMeters, double haversineDistanceInMeters, DirectedRoad from, DirectedRoad to, MapMatcherParameters parameters)
{
OnRoadDistInMeters = onRoadDistanceInMeters;
HaversineDistInMeters = haversineDistanceInMeters;
From = from;
To = to;
// COMPUTE TRANSITION PROBABILITY
double diffInMeters = Math.Abs(haversineDistanceInMeters - onRoadDistanceInMeters);
if (diffInMeters > parameters.TransitionDiffThreshold)
{
Probability = 0;
}
else
{
Probability = ProbabilityFunctions.ExponentialDistribution(diffInMeters, parameters.Beta);
}
}
public static Transition TransitionProbability(RoadGraph graph, ProjectToRoad projection1, ProjectToRoad projection2, MapMatcherParameters parameters)
{
DirectedRoad road1 = projection1.Road;
DirectedRoad road2 = projection2.Road;
//calculate on road distance
double onRoadDistanceInMeters;
Distance startingDist = projection1.DistanceToEnd;
Distance endDist = projection2.DistanceFromStart;
// Roads are the same:
if (road1.Equals(road2))
{
//negative if going backwards along road
onRoadDistanceInMeters = projection2.DistanceFromStart.DistanceInMeters - projection1.DistanceFromStart.DistanceInMeters;
}
// Road start or end on the same node
else if (road1.End == road2.End || road1.Start == road2.Start)
{
//make this transition impossible
return(Transition.ImpossibleTransition(road1, road2));
}
// Roads are connected (can be same road in opposite direction)
else if (road1.End == road2.Start)
{
onRoadDistanceInMeters = startingDist.DistanceInMeters + endDist.DistanceInMeters;
}
// Try connect roads using Dijstra
else
{
List <DirectedRoad> path;
if (PathFinding.DijstraTryFindPath(graph, road1.End, road2.Start, parameters.DijstraUpperSearchLimit, out path))
{
Distance connectingDist = Distance.Zero;
foreach (var road in path)
{
connectingDist += road.Length;
}
onRoadDistanceInMeters = startingDist.DistanceInMeters + connectingDist.DistanceInMeters + endDist.DistanceInMeters;
}
else
{
//cannot connect up roads. transition probability is zero
return(Transition.ImpossibleTransition(road1, road2));
}
}
Distance haversineDistance = projection1.Coordinate.HaversineDistance(projection2.Coordinate);
return(new Transition(onRoadDistanceInMeters, haversineDistance.DistanceInMeters, road1, road2, parameters));
}
