Recording GPS tracks

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A good way to get involved in the OpenStreetMap project is to upload GPS track logs (GPS traces). Recorded by your GPS device, the typical track is a record of your location every second, or every meter. The collected data can be displayed as a background of thin lines or little dots within the map editor. These lines and dots can then be used to help you add map features (such as roads and footpaths), similar to tracing from aerial imagery. GPS Satellite NASA art-iif.jpg
  Record   Convert   Edit   Upload   Accuracy   GPS Reviews  


Recording GPS tracks requires a GPS Receiver with the ability to save your location. A GPS Receiver is a device which allows you to accurately pinpoint your position, by receiving radio signals from GPS satellites. To record tracks and/or waypoints, you will need to select a GPS unit with this function — a specialized unit, but also a smartphone are both good candidates.

If you are hosting a mapping party, you can borrow the GPS Units for Loan

Types of GPS receivers

A collection of GPS receivers.

There are many types of GPS receiver, from a simple logger to smartphones with embedded GPS. The most useful for OpenStreetMap listed below.

  • GPS Loggers
    These are typically small devices which are used to record track logs. Although some include a small monochrome LCD screen for displaying basic settings and accuracy measurements, GPS Loggers do not provide map displays or navigation features. Some loggers can be connected via USB or Bluetooth to a laptop or phone in order to provide live location data. As they do not have a large display, the battery life can be 24+ hours.
  • Hand-held / Sports GPS
    Hand-held or Sport GPS receivers are targeted to the outdoor activities sector. They provide a small colour screen showing a map, and may provide navigation features (e.g. for trekking paths). Generally these are rugged devices that are splash-proof and sometimes waterproof.
  • In-car SatNav
    With a large colour map display, the main function of In-car SatNav devices is that of navigation. Although some can also record GPS tracks, this is not true of all. Away from a power supply the battery life tends to be quite short (often 3 hours or less).
  • Smartphone / Tablet
    Many smartphones and tablets include a GPS chip. Apps can be installed to provide the ability to record GPS tracks, provide navigation features, and even edit OpenStreetMap directly. Battery life is shortened when the GPS is switched on.
  • Precise positioning receivers
    A hardware receiver can emit raw data that can be post-processed to centimeter or decimeter accuracy using post-processing software.

See GPS Reviews for a list of reviews of GPS devices by OSM contributors.

How-to guide

With hundreds of GPS devices available, providing detailed instruction for all of them is infeasible. The following guide therefore provides generic advise to help you get started. Not all the steps may be necessary (or possible) on your particular device. If you need any help, please ask questions on the mailing lists or IRC.

Prerequisites

  • Check if your GPS unit has a "Snap to road" or "Lock on road" option, make sure that option is switched OFF, or you will end up merely recording a direct copy of the map loaded into the GPS unit, which is not only a copyright infringement (unless your map was downloaded or derived from OpenStreetmap), but is possibly going to be less accurate than the track you would otherwise record. On Garmin devices, it's on the first page of the map setup.
  • Set the position-recording frequency to the highest possible, depending on the memory of your device, the foreseen length of your track, and the speed at which you're travelling. If possible, set it to "every second".
  • Mount your GPS unit to your vehicle (if applicable and needed). Maybe a simple homemade GPS mount can help.
  • If you want to update the OSM map yourself afterward, take what you need to record the details of what you encounter along your track — notepad, voice recorder, digital or video camera, etc. Software such as JOSM will allow you to synchronize your recordings with your path, for example, place the pictures on the map where you took them.

Record the track

GPS traces of hiking trails recorded during a mapping party in Slovakia (watch video)

Go for a walk or a cycle ride or a drive (or whenever you take any kind of journey)

  1. Switch your GPS on at the start of the part of the journey that you want to map
  2. before you move, wait for a very good fix, i.e., until your GPS has locked as many satellites as possible. (See below for technical details.)
  3. Clear any track recorded previously, especially if the previous step recorded many false points.
  4. If necessary, set the GPS to tracking mode so that it records your journey.
  5. If you plan to make up the roads later, take notes of the street names and other features, unless you already know them. You cannot later get them from or check them on a map, as this would infringe copyright.
  6. Record your route along any linear feature — rivers and waterways, footpaths, bridleways, rail and tramways, and any other fixed linear features are of interest to OSM. We want points of interest and area information also, so add this information in your travels where you can.
  7. If supported by your device, you can record waypoints, too, to mark roundabouts, churches, starts and ends of bridges, etc.

Next steps

Once you have recorded a GPS track you can upload it to OpenStreetMap. Some devices (mainly smartphone apps) allow you to directly upload your recorded tracks. For all other devices you will need to copy the file to your computer before uploading via the web interface. Depending on the file format, you may also need to convert the file.

After uploading your GPS track, you may wish to use it to help add map features, similar to tracing from aerial imagery. See the Beginners' guide for more details.

Frequently Asked Questions

Can I use a smartphone?

It depends. Most smartphones do include GPS receivers and you can record track logs using one of the numerous available apps. Unfortunately the accuracy between phones can vary greatly, even between models from the same manufacturer! It can be very difficult to work out the technical accuracy of a GPS track, but a good compromise is to compare your results to other sources. Have a go at recording a track and check that it is smooth (does not jump all over the place) and is roughly in line with GPS tracks recorded by others (preferred), and/or aerial imagery (least preferred due to inaccuracy of aerial imagery in hilly areas).

Available apps include OSMtracker (Android) and OSMtracker (Windows Mobile).

Note: Recording GPS tracks on a smartphone will result in the battery running out quicker.

Can I use a car SatNav?

Not all car 'SatNavs' include an option to record GPS tracks, and if it does it me within a hidden service menu. Try searching for your particular model number online or ask in the mailing lists or IRC. Be aware, that even if you can record a track, it may not be practical due to the short battery life (less than 3 hours is common if the screen remains on when recording).

What to record?

Anything, as long as it reflects a real world feature. For example, try to avoid tracklogs of flights, as these could be distracting or confusing to other map contributors. Don't worry if you don't have the time to edit the map features after uploading a GPS track - the track on its own is helpful for others. Also tracklogs of roads that have already been mapped are also useful, as they can help to validate the true path of a road by providing more sample points.

How accurate is my GPS track?

The accuracy of GPS data can vary greatly between GPS receivers. It is also affected by your surroundings, the weather and the position of GPS satellites at the time of recording the track. For more information see Accuracy of GPS data.

See also

Other means to get data for mapping are described on Mapping techniques.