org.placelab.client.tracker
Class CentroidTracker

java.lang.Object
  org.placelab.client.tracker.Tracker
      org.placelab.client.tracker.BeaconTracker
          org.placelab.client.tracker.CentroidTracker

All Implemented Interfaces:

SpotterListener

public class CentroidTracker

extends BeaconTracker

A simple tracker that computes the geometric center of the current set of readings. Right now, this is the best general purpose Tracker for WiFi because it produces the most accurate Measurements.

Field Summary

Fields inherited from class org.placelab.client.tracker.BeaconTracker

WIFI_MAX_DISTANCE

Constructor Summary

CentroidTracker(Mapper m)

Method Summary

boolean	acceptableMeasurement(Measurement m) Returns true if the tracker can make use of this reading to meaningfully update the estimate.
Estimate	getEstimate()
protected void	resetImpl() Subclasses should implement this to reset themselves to their initial state.
void	updateEstimateImpl(Measurement m) updateEstimateImpl uses the passed measurement to compute a simple geometic center.
void	updateWithoutMeasurement(long durationMillis) This method notifies a tracker that time has elapsed without a new mesurement.

Methods inherited from class org.placelab.client.tracker.BeaconTracker

findBeacon, findBeacon, getMapper, pickBeacon, pickBeacon

Methods inherited from class org.placelab.client.tracker.Tracker

addEstimateListener, fireEstimateUpdate, getLastUpdatedTime, gotMeasurement, numberOfMeasurements, removeEstimateListener, reset, spotterExceptionThrown, updateEstimate

Methods inherited from class java.lang.Object

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

Constructor Detail

CentroidTracker

public CentroidTracker(Mapper m)

Method Detail

getEstimate

public Estimate getEstimate()

Specified by:

getEstimate in class Tracker

Returns:

The Tracker's latest Estimate

updateEstimateImpl

public void updateEstimateImpl(Measurement m)

updateEstimateImpl uses the passed measurement to compute a simple geometic center.

Specified by:

updateEstimateImpl in class Tracker

Parameters:

m - use this to update your Estimate

acceptableMeasurement

public boolean acceptableMeasurement(Measurement m)

Description copied from class: Tracker

Returns true if the tracker can make use of this reading to meaningfully update the estimate.

Overrides:

acceptableMeasurement in class BeaconTracker

Parameters:

m - returns true if this is a BeaconMeasurement

updateWithoutMeasurement

public void updateWithoutMeasurement(long durationMillis)

Description copied from class: Tracker

This method notifies a tracker that time has elapsed without a new mesurement. This gives the tracker a chance to update its estimate to account for predicted motion.

Specified by:

updateWithoutMeasurement in class Tracker

resetImpl

protected void resetImpl()

Description copied from class: Tracker

Subclasses should implement this to reset themselves to their initial state.

Specified by:

resetImpl in class Tracker