In any project working to preserve traditional knowledge, it is important to get a clear idea of the places and the natural resources significant to the local community. Using a map alone can be difficult and can lead to inaccuracies, especially in areas of thick jungle, open desert or other environments where there are no clearly recognizable landmarks or reference points. In these cases, a Global Positioning System (GPS) can be used to obtain accurate data which, when transferred to an application such as Google Earth (GE), can be used to create a map that is easily updated and shared.
What is GPS?
The Global Positioning System (GPS) is a navigation system developed by the United States military. Satellites orbiting the Earth transmit microwave signals that can be picked up by special receivers to provide data on the latitude, longitude and altitude of the position of the receiver.
Making a map using GE requires only two pieces of equipment: a GPS receiver and a computer. To make the system as mobile as possible the receiver should be a robust handheld type plus a laptop computer that can also connect to the internet when required.
If you are already familiar with an area, you can create your own map with Google Maps without information from a GPS receiver. You can select whole areas or plot routes or individual points, give them descriptions and add photos or videos. You can share the map via email or by sending the unique web address to others. It is even possible to download the data as a KML file, which can be opened in Google Earth, to get a satellite view of the area.
The receiver usually comes with a connection cable that attaches to the computer via the serial (9 pin) or USB port. Note that only Magellan and Garmin receivers are currently directly compatible with GE. Data from other devices, however, can be used by saving the files onto your computer as kml, gpx or loc, which can all be opened in GE. There is also software available to convert other types of files (see box).
Google Earth combines satellite imagery, aerial photographs and geographical information systems (GIS) data. It runs on Windows XP, 2000, Vista and Macintosh OS X 10.3.9 operating systems or higher. Google Earth (GE) requires 200MB of space on the hard drive, a 3D graphics card and a broadband internet connection, although it is possible to use the program offline (see below). GE is free to download, but to make maps you will need Google Earth Plus. Subscription costs US$20 per year but it is only this version that allows you to import files from the GPS receiver. Google Earth Pro has more features but is much more expensive (US$400 per year) and is intended for commercial use.
Plotting the map
Travel round the site to be mapped, either on foot or using transport. The GPS receiver automatically records points along the route on the internal memory. These are called ‘trackpoints’. For example, if you walk the perimeter of a village or along a path to a water source, the receiver will record the exact route you took. If you pass other important features along the way, such as burial sites or food sources, enter these points manually. The receiver usually allows you to name and describe the points. These are referred to as ‘waypoints’. The same method can also be used to plot locations of crops in an area by travelling round cultivated areas and storing the route. The routes can be plotted and the relative land areas will be shown when the map is created.
Once all the information has been gathered, plug the GPS receiver into the computer via the USB or serial port cable (whichever is appropriate to the device you are using – if in doubt, check with the manufacturer). Transfer the files to the computer either by dragging and dropping them using a program such as Windows Explorer or with the software supplied with the receiver.
If you have already downloaded and installed GE, connect to the internet and start up the program. Go to ‘file’ and open the saved files. The exact routes, as taken at the location, will then be shown in GE. You can add extra descriptions, add photos, print the route and email it to others. Just look for the icons at the top of the GE window showing a small envelope, a printer and a map or click on the ‘Add’ menu.
It might also be useful to plot the map and add descriptions while still at the location, where local people can still give their input. This is still possible even without an internet connection. However, you will need to connect to the internet before leaving to the site. Once you connect the laptop to the internet, open Google Earth and zoom into the area to be mapped. Use the mouse to ‘fly’ around the area and along the general route of any paths to be followed. The information will be saved in the cache of the computer. To increase the cache, and therefore the amount information that can be saved, go to the menu ‘Tools’ in GE, ‘Options’ and select ‘Cache’. Set the ‘Disk cache’ to 2000MB (2 gigabytes). You will then be able to import data from the GPS receiver and view the routs and other details in GE even after you disconnect from the internet.
Check if your GPS receiver is directly compatible with Google Earth or use the software below to convert GPS data files.
What GPS devices can I use with
GPS Visualizer is a free online utility that creates maps and profiles from GPS data (tracks and waypoints), street addresses and simple coordinates. Use GPS Visualizer to see where you’ve been, plan where you’re going or visualize geographic data. Also converts GPS data for use in Google Earth.
Earth Bridge links your GPS device to Google Earth. It is designed to bridge the gap between Google Earth and your GPS receiver. See your location on Google Earth in real-time and easily control your view. NOTE: Earth Bridge requires an NMEA-compatible GPS device connected via a serial (not USB) connection.
Hundreds of millions of people now use Google Earth and Google Maps to explore the world around them. Google Earth Outreach gives non-profits and public benefit organizations the knowledge and resources to create maps.