Beginners Guide 1.1
Collecting Data
There are a variety of forms of gathering data for OSM:
- GPS - This is currently the most common way of gathering data for OSM, and often preferred or even essential for collecting the initial geometry of roads, paths and other ways. If you want to add to an otherwise blank area and don't have a GPS, they are sometimes available for loan or you can create maps from other users' data.
- Local knowledge - Perhaps the best source of data, though, is if you simply happen to know the area very well, and thus for example the names of the roads, which shops or buildings there are, the local traffic rules and restrictions, or what ever else you might want to add to OpenStreetMap. If the basic road layout is already present, you often don't need any other technical devices and can start straight away.
- Bing and Yahoo! aerial imagery, Landsat and NPE maps are available to OSM for tracing data from. These sources can add greatly to OSM if used properly, but mapping an area properly requires someone on the ground to verify and to add information that cannot be gathered from these sources. You will find it much easier to trace something from aerial imagery if you know the area and already have a mental picture; there is also plenty of evidence to suggest that this tracing, like imports, can kill the motivation of on-the-ground mappers working in the area. So feel free to start with what you have, but exercise caution, consider local mappers, and plan a ground trip if you can.
- Your own photography or drawings - Make sure these are completely free to copy and use with OSM. Most data is not as free as you would think.
- Data may already be collected that requires people to convert it into a map. See local and global mapping projects.
- Seeing mistakes in a map and fixing them - map bugs are collected for instance by skobbler's osmbugs.
For all of the above sources, accuracy varies! This page on Accuracy discusses some common errors made when the lovely data you have taken lots of effort to obtain misleads you, and why you should not always edit data that appears 'wrong'.
Don't use copyrighted data
Most data that you find on the web is copyrighted, including "free" maps like Google maps or Bing maps. You may never use copyrighted resources because it can cause a lot of trouble to OSM. As a rule of thumb, use no external resources except those available in the editors. If you think you found a non-copyrighted resource that isn't available in the editors, please discuss it first on the mailing list talk@openstreetmap.org .
What data to add
There is a lot of data that can be gathered and put into OSM: from common things such as 'street names' right down to fine details which includes things like parks, postboxes, hedgerows and cairns. Different people find different things more important, usually influenced by their main method of transport. If you feel it helps people find their way, then map it! A nice selection of some of the most commonly mapped features and the way to describe them in osm can be found on the map features page. But remember you aren't limited to what is listed there, so be creative and map what is important to you!
Commonly mappers increase the detail as they go on, but start with the basics. So the main road network tends to be a good starting point, and lesser things such as footways, or postboxes are among the final bits to be added. Again this varies greatly for different people so there is no 'one way' that it should be done.
