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Global Positioning System (GPS) Workshop Written by Barbara Parmenter
Updated by Carolyn Talmadge
Tufts Geospatial Services
GIS at Tufts http://gis.tufts.edu
E-mail: gis-support@elist.tufts.edu
Geospatial Tools at Tufts
• Geographic Information Systems (GIS)
• Remote Sensing
• Global Positioning Systems (GPS)
• Online mapping
What is GIS? A system of computer software, hardware, data and personnel to help create, visualize, store, manipulate and analyze information that is tied to a spatial location.
GIS allow users to:
• Visualize and interpret patterns and relationships
• Analyze spatial information and trends
• Ask interactive spatial questions
• Predict future impact and create models
• Develop effective solutions
• Display and communicate spatial information
Remote Sensing
• Imagery produced by monitoring devices that don’t make physical contact
• Satellites, Aircraft, Spacecraft, Etc.
Remotely Sensed Imagery
Measurement or acquisition of information about the environment by aircraft, spacecraft, or satellite
Aceh City, Indonesia Pre and Post Tsunami
Earthquakes since 1987
Major Fires since 2001
Interpretation of satellite imagery…
Global Positioning System (GPS)
A system of satellites & receiving devices used to compute positions on the Earth.
• GPS space segment consists of a constellation of satellites transmitting radio signals to users.
• Fly in “Medium Earth Orbit”
• U.S. Air Force maintains at least 24 GPS satellites
• Each Satellite circles the earth 2x /day
• 4 satellites required for accurate location reading
• GPS units calculate the time and distance to satellites in order to locate your position on the earth (Latitude & Longitude).
GPS Space Segment
Global Positioning System (GPS)
• GPS surveys provide data to input into GIS
• Records Locations of Features in the field:
• Survey locations
• Health centers
• IDPs
• Dwellings
• Pot holes
• Wells
• Hiking Trails
• Etc.
Global Positioning System (GPS)
• Accuracy • Handheld: 3-10m • Differential GPS: 3m – 1cm
• Cost
• Handheld: $150 - $400 • DGPS: $2,500 and up • Juno ST (DGPS) sub 2-3m, $600
• Challenges
• Tree canopy, urban canyons, tall buildings, etc.
• Ruggedized Unit
• Bring extra batteries, car charger, etc.
• Capture additional data while doing survey
GPS: Community Surveys Internally Displaced Persons: Santa Marta, Colombia
Location of survey respondents
Dr. Karen Jacobsen Feinstein International Center
Map of Centro barrio in Santa Marta depicting random sample points
GPS: Health Tracking Monkey Locations in Kathmandu
Potential GPS Projects?
• Ideas?
• You may not need GPS if you can features on aerial photography (e.g., in Google Maps)
• You need GPS when:
• You can’t see the features in available imagery
• You need to record other information about the features
• Measured data
• Survey information
Data Collection Preparation – Read this Document!
Example from elephant dung sampling project in Nepal
Data Collection Preparation
Let’s collect data outside…
Let’s collect data outside…
Let’s collect data outside…
Major points….
• Plan ahead and be prepared
• Prepare a data collection
• Plan for backing up your work (Chaos, theft, loss, etc.)
• Think like a database
• Practice before you leave for the field
Let’s head out We’ll talk and learn about the GPS units
Then split into groups of two and collect waypoints
Other GPS resources at Tufts…
Follow the PowerPoint from here on… We’ll walk around and help you
Major Tip: Split the screen so that the PowerPoint takes up just half or less, and you can see the other programs…
Create a folder in your home (p) drive (or other drive) to save your files.
Downloading data from the GPS unit
1. Turn on your GPS unit
2. Plug your GPS unit into the USB port using the USB cord
3. Wait until you get message that Garmin USB GPS driver successfully installed
Downloading Data
• We use a freeware program called DNRGPS
• From Minnesota Department of Natural Resources
• You don’t need to download this in the lab – we have it installed already – next slide!
In the Tisch GIS lab, go to Start – All Programs – GIS Applications – GPS Applications - DNRGPS
In Mugar lab, go to Start – All Programs – GIS - DNRGPS
Or search for the program in the start menu
After opening DNR GPS, you should see it connecting to your unit…
To download your waypoints…
You should see something like this…
First, save as a Google Earth KML file… Save the KML file in your new GPS Tutorial Folder in your P Drive (or selected drive).
Immediate Gratification Double-click on your KML file in your GPS Tutorial Folder…
Next, save to a tab-delimited text file…
Save to a tab-delimited text file…
This is what a tab-delimited file looks like if you double-clicked it…
It’s a common format for database files…
But we need to create an Excel file in order to include the info you collected in your field data collection sheet
1. Open Excel
2. Choose File – Open and find the text file you saved
Delete unnecessary columns…
You can decide – just make sure to keep the IDENT (waypoint ID) column and your Latitude and longitude columns. Maybe time as well!
Save as an Excel (.xlsx) file…
Add the information from the field collection sheet and save again…
Add a column for “Feature Type”, “Condition” and “Remarks”.
Don’t forget to also add a column for your GPS Unit Number!!
For backup purposes (your computer is stolen, the GPS unit drops in the river)…
• Print out copies
• Save your field collection sheets!!
• E-mail or upload the Excel file somewhere safe
• For now, close Excel
Tip: every Tufts student and faculty has access to 20gb of cloud storage through tufts.box.com
If you have a Gmail or Google account, go to maps.google.com and sign in.…
Click on the search bar and then select “My maps” .
Press “Create” to open a new map.
Press “Import” to open your Excel File
First Screen
Second Screen
To open in Google Earth with your Data Collection Information Included
Double Click on the New KML File… Now you should be able to see your points + the information you added from your excel sheet.
There are several ways to import your data into ESRI ArcMap (Optional)…
1. From Google Earth: • Save your Google Earth Waypoints as a .KMZ and open in GIS
• Here is a link to the Tufts tutorial on how to Open Google Earth Files in GIS
2. From DNRGPS: • Save directly as an ESRI shapefile from DNRGPS
• Save as a .TXT file and Import using “Add XY Data”
• Refer to Downloading GPS Data with DNRGPS & Importing into ArcMap
Questions? This PowerPoint can be found on the Tufts GIS Center web site – http://gis.tufts.edu – under Online Tips and Tutorials – GPS Guides
Good luck & Happy Mapping
Carolyn Talmadge
GIS Specialist, TTS
GIS at Tufts http://gis.tufts.edu
E-mail: gis-support@elist.tufts.edu
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