Recording GPS tracks
|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.|
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.
Types 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.
See GPS Reviews for a list of reviews of GPS devices by OSM contributors.
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.
Record the track
Go for a walk or a cycle ride or a drive (or whenever you take any kind of journey)
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.
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 you 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).
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.
Other means to get data for mapping are described on Mapping techniques.