Surveying with a GPS
Learning to edit is one of the key parts of mapping - that is how you
add information to the actual map. But the other task is collecting the
information itself - that is, going out and surveying an area.
In this chapter we will see what a GPS does and how it works. You will
learn how to operate a GPS, and how to use it to create maps.
Here we will explain how to operate the Garmin eTrex Vista HCx, a
common GPS used for mapping. There are many other models of GPS which do
the same thing, so if you are working with a different one, don’t worry
– the principles remain the same.
What is a GPS?
A GPS is like a mobile phone, except that instead of receiving radio
signals from telephone companies, it receives signals from satellites
that are going around the Earth. By receiving these signals from the
satellites, a GPS is able to calculate your exact location on the
planet. It records this location in coordinates, which are two long
numbers. One number tells you how far East or West you are – this is
called longitude. The second number tells you how far North or South you
are – this is called latitude. Every place on Earth has unique
For example: -8.639298 Latitude, 116.311607 Longitude is a location in
Turn on the GPS
Before you turn on your GPS, go outside where you have a clear view of
the sky. Because the GPS determines your location by receiving signals
from satellites, it won’t work indoors.
On the right side of your GPS, press and hold the Power button. The GPS
will start, and it will show you the Satellites page. You should see
something like the image below. Your GPS is looking for satellite signals.
When it has connected to three or more satellites, it will have your location.
Once your location is determined, the Satellite screen will disappear
and you will see the main menu.
Navigate the GPS
- The GPS has different screens and menus that allow you to do
different things. To switch between screens, press the button marked
“X”, just above the power button on the right side of the device.
This button also serves to go back. If you press something by
mistake and would like to cancel or go back, press the “X” button.
- By pressing the X button, you should be able to flip through
different screens that will look something like this:
If you return to the Satellites page, you can see that you are
connected to three or more satellites. In the upper left corner are
your coordinates, your latitude and longitude.
Flip to the Map page, and you can see a map of where you are. If you
have added OSM maps to your GPS, you may see roads and places.
Otherwise, the map may look quite blank. Zoom in and out by pressing
the up and down arrow buttons on the left side of the GPS.
Further information where to obtain OSM maps for Garmin devices and how to install them can be found
in the OSM wiki
Tracks and Waypoints
Your GPS records two kinds of information that are useful for creating
maps or saving the coordinates of a place. First, it allows you to save
your location in the memory of the GPS. When you save a location, the
coordinates will be saved with a name. For example, your first saved
point will be named 001, the second 002, and so on.
If your GPS does not start at 001 and you would like to clear the
previous points, go to the “Find” icon in the main menu.
Hit “waypoints” and then the submenu button on the right side to
display the Waypoint submenu. Scroll down to “Delete” click
“all symbols” and “Yes”.
When you save a
point, you can write down the number on a piece of paper, along with a
note about what it is, and any attribute or indicators you would like to
know. Saved locations on your GPS are called waypoints.
Second, your GPS
can save what are called tracks. While a waypoint only saves a single
location, a track will save a series of locations wherever you move. For
example, the track will record your location every one second, or every
one meter, and the result will be a series of dots that show the path of
where you have been. Tracks are useful for mapping objects that are
represented by lines or shapes, such as the course of a road, or the
shape of a field.
Save Your Location
- To save your current location as a waypoint, click the “X” button
until your reach the Main Menu. Using the joystick, move it so that
“Mark” is highlighted on the screen. Push the joystick button down
to open the “Save Waypoint” page. Alternatively, you may press the
the joystick button on any page until the “Save Waypoint” page opens.
- You can see on this page some information about the waypoint that
you are saving. First is the name. If this is your first waypoint,
it probably reads “001”. This is the number you should record on
paper along with the information you want to collect with this
object. Next you will see the time and date when the point is
recorded. Below that are the coordinates, followed by the altitude.
- Use the joystick to move to the “OK” button at the bottom of the
screen. Press the joystick button down to save this point. Be sure
to write down the number of the point, along with what the place is
and any other information you want to record about the place in your
- Press the “X” button to go to the map page. You should now see your
point on the map.
Turn on the Track Log
- Now that we have learned how to save points, let’s learn how to turn
the track log on and off. When the track log is turned on, it will
automatically record your path. It’s good practice to turn on the
log when you begin mapping, and turn it off when you are finished.
You will then be able to look at the track on a computer and see the
path that you mapped. If you would like to map the course of a road,
it is a good idea to save a waypoint at the beginning and end of the
road, writing in your notebook the name and type of the road, and
any other important information about the road.
- To turn on the track log, click the “X” button until your reach the
page that says Track Log.
- If you would like to empty the track log to delete earlier
recordings, use the joystick to select “Clear”, and press the
joystick down. The bar at the top should read “0%”.
- To turn on the log, move the joystick to highlight “On”, and press
the joystick down. The track log is now recording your path.
- Under the “Set up” option, you also can set time or distance intervals
to track. Time intervals instruct your GPS to record your location at
given intervals. If you have a memory card in your GPS, it is good
practice to set this to 1 second, meaning that every second your location
will be added to the track log. This may be useful when detailed surveys
- Press the “X” button to go to the map page. As you move you will see
your track shown as a series of dots.
Copy Waypoints and Tracks to the Computer
When you are finished mapping with the GPS you will want to copy the
points and tracks to your computer so that you can open them in JOSM.
One way to copy the waypoints and tracks is to you use the free software
that Garmin provides, called BaseCamp. It can be downloaded
here. However, in
this section we will use a program called GPSBabel, which offers a few
Attach GPS to the Computer
- First, turn off the track log on your GPS, by going to the
track page and selecting “Off”.
- Attach the GPS to your computer with the cable. One end should plug
into your computer’s USB port, and the other goes into the back of
the GPS, beneath the rubber flap at the top. The GPS should be
turned on to copy the points and tracks.
Install GPS Drivers
- You may need to install GPS drivers on your computer. You can download
the drivers at the Garmin Website.
- Click “Download” to get the installation file. Locate it on your
computer, and double-click to install.
Linux systems (at least Fedora) do not need special drivers to communicate
with a Garmin device (at least the eTrex Vista HCx). Just make sure that your
Garmin is powered and plug it into your compure with a USB cable. You can use
GPSBabel (as instructed below) or GpsPrune to grab the saved data from your device.
Get the GPSBabel Setup Program
- GPSBabel is a program that allows us to copy data from the GPS. If you
have a copy of GPSBabel on a CD or usb flash drive, you can skip to
the next section.
- If you don’t have GPSbabel already, open your web browser
and go to www.gpsbabel.org
- Click “Downloads” at the top of the page.
- Scroll down the page. If your computer uses Windows, you want to
download the installation file for Windows. Click “GPSBabel-1.5.2-Setup.exe”.
The file will be downloaded to your computer.
- Locate the GPSBabel setup file on your computer. Double-click it to install.
- Click “Next”.
- Click “I accept” and “Next”.
- Continue clicking “Next” until the program installs.
- When the program has finished installing, click “Finish” to start GPSBabel.
Copy Tracks and Waypoints
- Click in the circle next to the word “Device” at the top of the
- In the dropdown menu labelled “Format”, select “Garmin serial/USB
- Go down to the middle of the window, under Output. In the dropdown
menu labelled “Format”, select “GPX XML”:
- Click “File Name” and type a name for your saved file. It should be
something that describes the data, such as the date and the
location. For example, jakarta-07-07-2011
- Make sure your GPS is connected to the computer and turned on.
- Click “Apply” in the bottom right corner of the window.
- If all goes well you should see a bar move across the screen,
indicating that the data is being retrieved from the GPS. When it is
finished, your points and track will be saved in the file that you
Open in JOSM
- Now open JOSM. On the top menu, click “File” and then click “Open…”
- Find and select the file that you created with GPSBabel. Click “Open”.
- You should now see your points and tracks loaded into JOSM.
Congratulations! You should now have an understanding of how to use the
GPS. If you haven’t already, practice saving points of some important
In this section we learned how to collect points and tracks and open them
in JOSM. Later, we will use this information to add new
places to OpenStreetMap.