This is an article based on the presentation given at StaffsLUG on 10th March 2010 by Russ Phillips.
Download the presentation.
What is it? How Useful is it?
OpenStreetMap (OSM) is an attempt to create free geographic data for the whole world. The important point here is that the data is free, not just the map images. Editing is done in a wiki-like manner, which allows OSM to respond very quickly to change. After the Haiti earthquake earlier this year, OSM had updated maps within a couple of days, showing damaged buildings, blocked roads, refugee camps etc. This data was converted into maps for GPS receivers, allowing aid workers to navigate much more easily.
In March, Roy Van Keulen, TomTom’s VP of ecommerce, told PC Pro, "There are services like OpenStreetMap, and it’s good, but sometimes there’s not a bridge when it told you there would be." In fact, in at least one instance, the opposite is true. In November 2009, floods rendered bridges in Workington (Cumbria) impassable. Within a day, OSM’s map had been updated to show the bridges as being inaccessible. In April 2010, the army opened a temporary bridge, and on the day it was opened, OSM was updated to show it as being usable. TomTom’s web site still tried to route people over the damaged bridges, and didn’t show the temporary bridge at all.
Like TomTom, OSM isn’t perfect. Despite what Mr Van Keulen seems to think, the problem isn’t that OSM will tell there is a bridge where there isn’t one. The real problem is that OSM doesn’t know about all the bridges, roads etc that do exist. It’s improving all the time, though, and at the start of May 2010, OSM had all UK motorways and B roads, about 90% of A roads, and 70% of other roads. OSM doesn’t just know about roads, though – it also knows about almost all UK hospitals, and 20% of pharmacies.
Not Just a Pretty Map
As I said in the introduction, OSM isn’t just a map – it’s geographic data. This is an important distinction, because having access to the raw data allows developers and users to use it for unexpected things. If your only access is an API, then you can’t do anything that the API doesn’t cater for, which effectively means you can’t do anything that the API writers didn’t think of.
OSM data is used for many different things. I wrote a web site called Healthwhere which allows a user to find a pharmacy or hospital close to them. It’s specifically designed to be just as usable on my phone’s 2″ screen as on my desktop’s 19″ screen.
OpenCycleMap is a map designed for cyclists. As such, it shows cycle routes much more prominently than motorways, since they’re far more useful for cyclists. This is only possible because OSM’s raw data is available. It wouldn’t be feasible to take a standard road map and make the cycle routes much more obvious than the motorways.
HaptoRender is a project to create tactile maps, that can be read using fingers, designed for use by the blind. A tactile map based on OSM data was made in May, 2009, and displayed at that year’s OSM conference.
Collecting Data
Most OSM data is collected using a hand-held GPS, whilst driving, walking or cycling. The GPS is set to record a track, which is then uploaded to OSM’s servers and used to trace the roads, paths etc.
If you are interested in buying a GPS, the GPS Reviews wiki page has reviews of many different models.
As many phones now have GPS’s built in, software has been developed to make use of these.
For iPhone users, there is Mapzen, an app for collecting points of interest (restaurants, pharmacies, etc).
For the Android, there is AndNav2 and Vespucci.
The OSM wiki has a page listing apps for other phones.
You Don’t Need a GPS!
Using a GPS is the preferred way to collect data, partly because you can collect all sorts of extra data while walking around (opening times, location of litter bins, etc). However, if you don’t own and don’t want to buy a GPS, you can still help improve the map.
OpenStreetBugs is a web site that makes it easy to report bugs in the map. Simply mark the location and add a description of what is wrong.
Walking Papers is a site that allows you to print out a map of an area. You then annotate it with notes, scan & upload it, and use it as a reference to update OSM. If you don’t have a scanner, you can post the map to them and they will scan and upload it for you.
Healthwhere can update and add details to pharmacies and hospitals.
Ordnance Survey OpenData is a collection of data from the UK’s Ordnance Survey mapping agency that has been released under an OSM-compatible licence. OSM editors support tracing from this data.
Finally, out-of-copyright maps such as those at NPE Map can be used, though you should only trace features that you know haven’t changed.
Editing the Map
To edit OSM, you must first register. Once you have an account, there are several options.
Potlatch is the online editor, accessed by clicking the Edit tab on the OSM web site. It’s designed to be simple to use, but requires Flash (the latest version of Gnash should work).
I wrote an article for the StaffsLUG web site entitled "Add a Road to OpenStreetMap in 5 Minutes", which describes how to register and use Potlatch to add one or more roads. The whole process can be done in under five minutes.
JOSM is an off-line editor. Once run, you can download data, edit it, then upload the changes.
There are other options available, but Potlatch and JOSM are the primary editors. Whichever method you use, the Map Features wiki page is a useful reference. Users are free to use any tag, but those described on Map Features are more likely to appear on the map and be recognised by software that uses OSM data.
