org.placelab.client.tracker
Class SmoothingTracker

java.lang.Object
  org.placelab.client.tracker.Tracker
      org.placelab.client.tracker.SmoothingTracker

All Implemented Interfaces:

EstimateListener, SpotterListener

public class SmoothingTracker

extends Tracker

implements EstimateListener

This simple smoother creates a reading that is a mix of the last 2 Estimates produced by a wrapped Tracker. X and Y will not change by more than a fixed percentage, nor will the error if the Estimate has one.

Constructor Summary

SmoothingTracker(Tracker t)

Method Summary

boolean	acceptableMeasurement(Measurement m) Returns true if the tracker can make use of this reading to meaningfully update the estimate.
void	estimateUpdated(Tracker t, Estimate e, Measurement m) Implement this method to respond to updates from the Tracker(s) you are registered with.
Estimate	getEstimate()
Tracker	getTracker()
protected void	resetImpl() Subclasses should implement this to reset themselves to their initial state.
void	setDeviationThreshold(double newThreshold) Sets the threshold at which a new Estimate from the wrapped Tracker will have its standard deviation used without being smoothed with a previous Estimate's standard deviation.
void	setDistanceThreshold(double newThreshold) Sets the threshold at which a new Estimate from the wrapped Tracker will have its coordinate used without being smoothed with a previous Estimate's coordinate.
void	setMinDeviation(double newMin) Sets the minimum standard deviation an Estimate produced by this SmoothingTracker will have.
void	setNewToOldDeviationRatio(double newRatio) Sets the percentage by which the Estimate's standard deviation produced by this SmoothingTracke will change from its last Estimate in light of a new Estimate produced by its wrapped Tracker
void	setNewToOldRatio(double newRatio) Sets the percentage by which the Estimate's coordinate produced by this SmoothingTracker will change from its last Estimate in light of a new Estimate produced by its wrapped Tracker.
java.lang.String	toString()
void	updateEstimate(Measurement m) Called to give the tracker a new measurement.
protected void	updateEstimateImpl(Measurement m) Subclasses should implement this to do the actual work of updating their Estimate with the given Measurement.
void	updateWithoutMeasurement(long timeSinceMeasurementMillis) This method notifies a tracker that time has elapsed without a new mesurement.

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

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

Methods inherited from class java.lang.Object

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

Constructor Detail

SmoothingTracker

public SmoothingTracker(Tracker t)

Method Detail

toString

public java.lang.String toString()

getTracker

public Tracker getTracker()

setDistanceThreshold

public void setDistanceThreshold(double newThreshold)

Sets the threshold at which a new Estimate from the wrapped Tracker will have its coordinate used without being smoothed with a previous Estimate's coordinate. The default is 1000 meters.

See Also:

setDeviationThreshold(double)

setNewToOldRatio

public void setNewToOldRatio(double newRatio)

Sets the percentage by which the Estimate's coordinate produced by this SmoothingTracker will change from its last Estimate in light of a new Estimate produced by its wrapped Tracker. For instance, if newRatio is .5, then the new Estimate is produced in the following way: newLat = previousLat + (incomingEstimateLat * .5) and the same for the longitude.

See Also:

setNewToOldDeviationRatio(double)

setDeviationThreshold

public void setDeviationThreshold(double newThreshold)

Sets the threshold at which a new Estimate from the wrapped Tracker will have its standard deviation used without being smoothed with a previous Estimate's standard deviation. The default is 500 meters.

See Also:

setDistanceThreshold(double)

setNewToOldDeviationRatio

public void setNewToOldDeviationRatio(double newRatio)

Sets the percentage by which the Estimate's standard deviation produced by this SmoothingTracke will change from its last Estimate in light of a new Estimate produced by its wrapped Tracker

setMinDeviation

public void setMinDeviation(double newMin)

Sets the minimum standard deviation an Estimate produced by this SmoothingTracker will have.

updateEstimateImpl

protected void updateEstimateImpl(Measurement m)

Description copied from class: Tracker

Subclasses should implement this to do the actual work of updating their Estimate with the given Measurement.

Specified by:

updateEstimateImpl in class Tracker

Parameters:

m - use this to update your Estimate

updateEstimate

public void updateEstimate(Measurement m)

Description copied from class: Tracker

Called to give the tracker a new measurement.

Overrides:

updateEstimate in class Tracker

Parameters:

m - A measurement from a Spotter.

See Also:

Tracker.acceptableMeasurement(Measurement)

getEstimate

public Estimate getEstimate()

Specified by:

getEstimate in class Tracker

Returns:

The Tracker's latest 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.

Specified by:

acceptableMeasurement in class Tracker

updateWithoutMeasurement

public void updateWithoutMeasurement(long timeSinceMeasurementMillis)

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

estimateUpdated

public void estimateUpdated(Tracker t,
                            Estimate e,
                            Measurement m)

Description copied from interface: EstimateListener

Implement this method to respond to updates from the Tracker(s) you are registered with.

Specified by:

estimateUpdated in interface EstimateListener

Parameters:

t - the Tracker producing the Estimate

e - the Estimate produced by the Tracker

m - the latest Measurement used by the Tracker to produce the Estimate