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What to Do With Thousands of GPS Tracks. John Krumm, PhD Microsoft Research Redmond, WA. GPS Data. Microsoft Multiperson Location Survey (MSMLS). Garmin Geko 201 $115 10,000 point memory median recording interval 6 seconds 63 meters. 55 GPS receivers 227 subjects

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What to Do With Thousands of GPS Tracks

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What to Do With Thousands of GPS Tracks

John Krumm, PhD

Microsoft Research

Redmond, WA

GPS Data

Microsoft Multiperson Location Survey (MSMLS)

  • Garmin Geko 201

  • $115

  • 10,000 point memory

  • median recording interval

    • 6 seconds

    • 63 meters

55 GPS receivers

227 subjects

1.77 million points

95,000 miles

153,000 kilometers

12,507 trips

Home addresses & demographic data

Seattle Downtown


Greater Seattle

GPS Projects

  • Personalized Routes

  • Predestination

  • Location Privacy

Personalized Routes

One Driver A to B:

MapPoint plan

Empirically fastest

Shortest distance

Driver’s route

Percentage of trips in our data for which the driver’s actual route matched the…

Shortest route: 27%

Fastest route: 31%

MapPoint route: 39%

Neither shortest nor fastest: 60%

Julia Letchner, John Krumm, and Eric Horvitz, "Trip Router with Individualized Preferences (TRIP): Incorporating Personalization into Route Planning", Eighteenth Conference on Innovative Applications of Artificial Intelligence (IAAI-06), July 2006.

Preferable Routes

  • Deflate cost of previously driven roads

  • Tested on ~2500 trips

    • 47% of computed routes matched actual

    • Only 11% of trips duplicated in data

One trip from GPS data

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Dynamic Map Matching

Goal: Infer actual route from noisy location data

Results on traditional problem cases

John Krumm, Julie Letchner, and Eric Horvitz, "Map Matching with Travel Time Constraints", Society of Automotive Engineers (SAE) 2007 World Congress, April 2007, Paper 2007-01-1102.

Going to the airport? Park with us for $8/day!

Traffic Warning

Destination Safeco Field(54% chance): 15-minute delay at I-405 & I-90. Suggest I-5 instead.

Destination Seattle Center (31% chance): Broad St. closed. Suggest Denny Way instead.


Where do you want to go today? We already know.

Regular nav system

Upcoming traffic

Relevant ads

Optimize hybrid charge/discharge

John Krumm and Eric Horvitz, "Predestination: Inferring Destinations from Partial Trajectories", Eighth International Conference on Ubiquitous Computing (UbiComp 2006), September 2006.


  • Previous destinations

  • Preferred ground cover

  • Efficient driving

  • Anticipated trip times

USGS Ground Cover: swamps unpopular as destination

Median error = 2 kilometers at halfway point of trip




John Krumm and Eric Horvitz, "Driver Destination Models",  Eleventh International Conference on User Modeling (UM 2007), June 25-27, 2007, Corfu, Greece.

Location Privacy

Why reveal your location to a 3rd party?

Congestion Pricing

Location Based Services

Pay As You Drive (PAYD) Insurance

Collaborative Traffic Probes (DASH)

Research (London OpenStreetMap)

John Krumm, "Inference Attacks on Location Tracks", Fifth International Conference on Pervasive Computing (Pervasive 2007), May 13-16, 2007, Toronto, Ontario, Canada.

Attack Outline

Median error = 61 meters

Correct name on 5%

Computational Countermeasures

Uncorrupted Data

Spatial Cloaking

Gaussian Noise, σ = 50 m

Discretize, Δ = 50 m

Mention this talk at any participating* Pizza Hut and receive free breadsticks!

* There are actually no participating Pizza Huts.

How Much Corruption?

Discretize, Δ = 50 m

Gaussian Noise, σ = 50 m


GPS Data

Personalized Routes

Map Matching

Driver Models


Location Privacy

How’s my talk? 1-800-555-TALK


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