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Wilfrid Laurier University Faculty of Arts
October 24, 2014
 
 
Canadian Excellence


First ever blood glucose map, derived from a CIHR study that combined GPS tracking with a continuous Glucometer. (c) Sean Doherty

GPS


Example Person-based GPS Tracked Data viewed in Google Earth

For over a decade, Dr. Doherty has been developing GPS-based technologies for tracking human activity patterns, including especially travel, exercise, and stationary activities.  Although the first attempts involved a suitcase full of equipment (!), he now uses GPS-enabled smartphones such as the Blackberry.  This further allows the GPS data to be wirelessly transmitted to a central server for storage, processing and display. Dr. Doherty has developed an algorythm and system (patent pending) for automatically detecting a wide-range of human activities (walking, driving, at-home, etc.), and applied this system in studies of diabetic, elderly, disabled children, as well as in a variety of consumer applications. 

Example GPS Tracked Data

Listed at the bottom of this page are some example person-based 1-second GPS tracked data viewable in Google Earth.  The raw data was collected using a Blackberry, compressed and transmitted wirelessly to a central servers, then processed to automatically detect the sequence of daily events (activities and trips).  These events were then displayed in an interactive on-line prompted-recall diary.  From there, the data was exported .kmz file, so that both the GPS raw data and activity-travel information could be viewed in Google Earth (http://earth.google.com/).  Google Earth is free software that allows a variety of spatial data to be viewed from different perspectives on the earth - if you haven't tried it yet, it is well worth exploring.

How to View the Files

Simply open the files and take note of the folders that appear at left, and the GPS trace that appears on the surface of the earth.  You are encouraged to "follow your nose" and experiment with different views and selections of data within the folders.  You'll be surprised at just how many different types of human behaviours are visible to the naked eye.  Of course, developing an algorithm to automatically perform this detection is another matter, for which Dr. Doherty is deeply engaged.  Here are some further notes and tips on exploring and interpreting this data:

GPS Points: in addition to plotting the points by longitude/latitude, the time, heading, and connection between points are all visible to aid in interpretation.  The triangular symbol used for each point points in the direction of movement.  If the times becoming annoying, goto "Google Earth-Preferences/Options-Choose 3D Font" and set the font size to 4; this will hide the times from display.

Folders:  the GPS data is organized into folders/sub-folders that represent the sequence of activities and trips automatically detected by the algorithm - a form of daily "diary".  Expand/collapse these to view more/less detail by clicking on folders:

- The "Schedule" folder lists them in time-ordered sequence, showing the start/end time, event type (activity or trip) and location name. 

- The "Events" folder organizes the activities and trips by type. Choose this folder or the schedule folder, BUT not both (since it displays the data twice then).

- The "Locations" folder contains single points of each location only (displayed as pushpins), calculated as the spatial average of all points associated with each activity. 

Experiment with different data selections:  click the whole "Schedule" folder to view all the data as a space-time path;  alt, click only the trips within the schedule folder and the entire "Locations" folder, for a more concise view (this avoids the large clumps of GPS points typical of stationary activities).  If you're interested only in certain types of activities, such as exercise or driving, explore the Events folder and click on only those of interest for display.

For more information on this data and how it is being used contact Dr. Doherty

Related Information Title Type
2009 Google Earth File - Extensive Example of GPS Tracked Data, Including a Variety of Exercise Document
2009 Google Earth File - Small Example of GPS Tracked Data, Automobile Focussed Document
2009 Google Earth File - The "M-Spiral" Etch-a-sketch Application of GPS Document