com.graphhopper.matching.util

Class HmmProbabilities

java.lang.Object

com.graphhopper.matching.util.HmmProbabilities

public class HmmProbabilities
extends Object

Based on 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.

Constructor Summary

Constructors

Constructor and Description
HmmProbabilities(double sigma, double beta)

Method Summary

Modifier and Type	Method and Description
double	emissionLogProbability(double distance) Returns the logarithmic emission probability density.
double	transitionLogProbability(double routeLength, double linearDistance) Returns the logarithmic transition probability density for the given transition parameters.

Methods inherited from class java.lang.Object

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

Constructor Detail

HmmProbabilities

public HmmProbabilities(double sigma,
                        double beta)

Parameters:

sigma - standard deviation of the normal distribution [m] used for modeling the GPS error

beta - beta parameter of the exponential distribution used for modeling transition probabilities

Method Detail

emissionLogProbability

public double emissionLogProbability(double distance)

Returns the logarithmic emission probability density.

Parameters:

distance - Absolute distance [m] between GPS measurement and map matching candidate.

transitionLogProbability

public double transitionLogProbability(double routeLength,
                                       double linearDistance)

Returns the logarithmic transition probability density for the given transition parameters.

Parameters:

routeLength - Length of the shortest route [m] between two consecutive map matching candidates.

linearDistance - Linear distance [m] between two consecutive GPS measurements.