Package com.graphhopper.matching

Class MapMatching

java.lang.Object

com.graphhopper.matching.MapMatching

public class MapMatching
extends Object

This class matches real world GPX entries to the digital road network stored in GraphHopper. The Viterbi algorithm is used to compute the most likely sequence of map matching candidates. The Viterbi algorithm takes into account the distance between GPX entries and map matching candidates as well as the routing distances between consecutive map matching candidates.

See http://en.wikipedia.org/wiki/Map_matching and Newson, Paul, and John Krumm. "Hidden Markov map matching through noise and sparseness." Proceedings of the 17th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems. ACM, 2009.

Author:

Peter Karich, Michael Zilske, Stefan Holder, kodonnell

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	MapMatching.Router

Constructor Summary

Constructors

Constructor	Description
MapMatching(BaseGraph graph, LocationIndexTree locationIndex, MapMatching.Router router)

Method Summary

Modifier and Type	Method	Description
List<Observation>	filterObservations(List<Observation> observations)	Filters observations to only those which will be used for map matching (i.e.
List<Snap>	findCandidateSnaps(double queryLat, double queryLon)
static MapMatching	fromGraphHopper(GraphHopper graphHopper, PMap hints)
Map<String,Object>	getStatistics()
MatchResult	match(List<Observation> observations)
static MapMatching.Router	routerFromGraphHopper(GraphHopper graphHopper, PMap hints)
void	setMeasurementErrorSigma(double measurementErrorSigma)	Standard deviation of the normal distribution [m] used for modeling the GPS error.
void	setTransitionProbabilityBeta(double transitionProbabilityBeta)	Beta parameter of the exponential distribution for modeling transition probabilities.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

MapMatching

public MapMatching(BaseGraph graph,
 LocationIndexTree locationIndex,
 MapMatching.Router router)

Method Details

fromGraphHopper

public static MapMatching fromGraphHopper(GraphHopper graphHopper,
 PMap hints)

routerFromGraphHopper

public static MapMatching.Router routerFromGraphHopper(GraphHopper graphHopper,
 PMap hints)

setTransitionProbabilityBeta

public void setTransitionProbabilityBeta(double transitionProbabilityBeta)

Beta parameter of the exponential distribution for modeling transition probabilities.

setMeasurementErrorSigma

public void setMeasurementErrorSigma(double measurementErrorSigma)

Standard deviation of the normal distribution [m] used for modeling the GPS error.

match

public MatchResult match(List<Observation> observations)

filterObservations

public List<Observation> filterObservations(List<Observation> observations)

Filters observations to only those which will be used for map matching (i.e. those which are separated by at least 2 * measurementErrorSigman

findCandidateSnaps

public List<Snap> findCandidateSnaps(double queryLat,
 double queryLon)

getStatistics

public Map<String,Object> getStatistics()