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General frequently asked questions. See also: Developer FAQ, Legal FAQ, FAQ about the proposed licence change.

In addition to this FAQ, there is a collaboratively edited question and answer site where you can read more questions about OpenStreetMap and ask your own.


Contents

Is it OpenStreetMap or Open Street Maps?

OpenStreetMap is the correct spelling. One word, three capital letters, one map. OpenStreetMap is also a Trademark.

Why OpenStreetMap?

Why are you making OpenStreetMap?

Geographical data (geo data) is not free in many parts of the world, like the United Kingdom. Generally these places have given the task of mapping to various government agencies who in return get to make money by selling the data back to you and me. If you live in one of these countries, then your taxes pay for the mapping and then you have to pay again to get a copy of it. In the USA crude data (such as TIGER) from the government, is in the public domain, however refined data and finished maps are generally commercially copyrighted.

Data from commercial mapping agencies contains lies, or Copyright Easter Eggs, to catch out anyone copying it. These easter eggs take the form of fake or missing streets, or features like churches and schools that don't in fact exist. If you make a map using their data, they can say "ah-ha! Gotcha!" from looking if you also copied these fake pieces of map. The map may also just be incorrect because for example you bought it a year ago and a path has been dug up in your local park since, or someone just made a mistake.

If you accept all of this then you still can't do anything with the data but photocopy it. In lots of places that's illegal too if you go beyond your fair use rights. You can't correct a street name, or add the pub/bar over the road, or use the data in a computer program without paying a lot of money. More money than you probably have. What about sending it to a friend, enclosing it in an invitation or posting it on a notice board? A lot of these are less legal than you might think.

Advances in technology like cheap GPS units mean you can now create your own maps, in collaboration with others and have none of the restrictions outlined above. The ability to do so allows you to regain a little bit of the community you live in - if you can't map it, you can't describe it.

Why don't you just use Google Maps/whoever for your data?

Short answer:

Because that data is copyrighted and owned by people like the Ordnance Survey. Google/whoever just license it. If we used it, we'd have to pay for it.

Long answer:

Most hackers around the world are familiar with the difference between "free" as in "free beer" and as in "free speech". Google Maps are free as in beer, not as in speech.

If your project's mapping needs can be served simply by using the Google Maps API, all to the good. But that's not true of every project. We need a free dataset which will enable programmers, social activists, cartographers and the like to fulfil their plans without being limited either by Google's API or by their Terms of Service.

At this point, the usual rejoinder is "Why don't you just get people to click a point on a Google map, then record the latitude and longitude in the Openstreetmap database? That's free, isn't it?"

Unfortunately not. The data used in Google Maps is either owned by Google itself, or sourced from NAVTEQ and Tele Atlas, two big mapping companies. They, in turn, have obtained some of this data from national mapping agencies (such as the Ordnance Survey). Since they've made multi-million pound investments in gathering this data, all these organisations are understandably protective of their copyright.

If you collect data from Google Maps in this way, you are creating a "derived work". Any such data retains the copyright conditions of the original. In practice, this means your data is subject to the licensing fees, and contractual restrictions, of these map providers. That's exactly what Openstreetmap is trying to avoid.

Please don't be misled by considerations of software copyright, or of Terms of Use. The Google Maps API can be incorporated into open source projects, sure. But this only governs how you use the software - it doesn't have any implications whatsoever for the data displayed by this API, which is still under copyright.

(It's not yet clear whether it's ok to create a derived work from aerial photography: some readings of UK law suggest that you can do this without 'inheriting' the copyright in the photography. A definitive ruling on this could open up new avenues for Openstreetmap and similar projects, but in the absence of such a ruling, we're continuing with the approach of sourcing our own, 100% independent data.)

Further reading:

  • Google Maps' Terms of Service. Note particularly the 'Map Information' section, and that:
    • "Geocoding data for map content in Google Local is provided under license by Navteq... and/or Tele Atlas... and subject to copyright protection and other intellectual property rights owned by or licensed to NAVTEQ, TANA and/or such other third parties."
    • "Also, you may not use Google Local in a manner which gives you or any other person access to mass downloads or bulk feeds of numerical latitude and longitude coordinates."
  • The Openstreetmap mailing list archives. You may want to search them for phrases like "derived works", and for a thread in October 2005 called "London locations".
  • For UK users, here's a useful set of links to copyright legislation.

How can a project like this create accurate maps?

By the very nature of the wiki-style process there is no guarantee of accuracy of any kind. Then again, few proprietary maps carry a guarantee of accuracy, either. In fact, some have artificially-introduced errors.

The essence of a wiki-style process is that all users have a stake in having accurate data. If one person puts in inaccurate data, maliciously or accidentally, the other 99.9% of people can check it, fix it, or get rid of it. The vast majority of good-intentioned participants can automatically correct for the few bad apples.

And as they say, your mileage may vary. The Wikipedia project has shown that a large amount of good quality data can be collected but it can be difficult to weed out the inevitable errors.

A full editing history is stored for each user. Since April 21, 2009, users can attach Wikipedia-like edit summaries to their edits, and there is a History tab on the main page that shows recent edits to the selected area.

At the moment the best way to answer this question is to judge for yourself. One way is to pick an area that you know well and use the OpenStreetMap viewer to see how well the map data corresponds to your own knowledge. Maybe you will see something wrong or inaccurate. More likely you will find there's nothing there yet. At this stage, our main challenge is to extend our coverage, without copying from existing maps. As on Wikipedia, it's easy to edit, so you can help!

You seem to have a lot of existing map data. Where did it come from?

We have a lot of very keen contributors!

We are also bringing in TIGER data for the US, and we have AND Data for the Netherlands (kindly donated), GeoBase data from the Canadian government, and we are always on the lookout for other Potential Datasources. However, all of our data must come from public domain or open licensed sources which are compatible with our OpenStreetMap License. Even in those areas where free data exists, there is generally a lot of room for improvement via our wiki-like community map editing process.

In areas where there are no such data sources (most areas) we have to start from a blank slate, and head out there to survey the streets ourselves. Despite starting from scratch, we have achieved a good level of completion in many places.

Why is the data sometimes inconsistent?

"OpenStreetMap is a free editable map of the whole world. It is made by people like you." Which means the database will always be subject to the whims, experimentation, and mistakes of the community; this is precisely OSM's strength since, among other things, it allows our data to quickly accommodate changes in the physical world.

Who owns OpenStreetMap?

You do. The data and software is owned by you, the contributors.

There is an organisation called the OpenStreetMap Foundation which exists to protect, promote, and support the project, but does not own the data.

What does your licence allow me to do?

We have a Legal FAQ which will give you some pointers, but it's not definitive and is the subject of some debate.

Since late 2007, the OpenStreetMap Foundation has been considering licence issues: here is the latest update.

How do I help?

How can I get involved?

There are lots of ways to contribute to the Openstreetmap project. If you have a GPS unit you can use it to collect data and use our online tools to add the data to our collection. If you don't have a GPS unit you can still help. Ways to help are listed on the Getting Involved page.

How do you communicate?

The OpenStreetMap community is large, and spread across many locations, speaking different languages, and focussing on different interest areas. So the answer is we don't always communicate very well! But we do our best.

We have various Contact channels.

See Contact for more information

Can I show my support by purchasing cool stuff?

Yes! See the Merchandise page for mouth-watering goodies.

Is there any ongoing scholar research on OpenStreetMap?

Numerous universities and schools worldwide are using OSM within the scope of research. See Scholar Research for more information.

Editing

I have GPS data, how can I use it to help OpenStreetMap?

You can upload your GPS tracklogs to OpenStreetMap, so that you and others can trace over them to draw maps. You'll need to be a registered OSM user before you do this. See tracks that others have uploaded.

Once you've done that, you can use the GPS as a guide to drawing roads and paths for OpenStreetMap. You can do this by:

  • edit your data online, using Potlatch, an easy-to-use Flash program that runs within your browser; or
  • edit at home using JOSM, which provides a powerful way to edit GPS data locally on your computer into sensible tracks before uploading them to the server (there are other editors, too);
  • and if you don't have a GPS you can still help, see Getting Involved.

I have public domain non-GPS data, how can I upload it?

If you have public domain data obtained from non-GPS sources (for example, a municipality's public information website), you can add it to our database. Be sure to confirm that the data is in public domain. If you are unsure about the licensing issues, or if it is a very large quantity of data, please discuss it first (Contact). We will be very interested to hear from you! You could also add an entry to the Potential Datasources list, and describe it on there.

For bulk uploading purposes, it may be best to use the API directly. A worked out example: Using curl to upload data. On the other hand, it may be better to review the data alongside existing OSM data using the layers feature of JOSM (convert your data to a .osm file to load in)

What images and maps may I use to make maps from?

Most maps have copyright restrictions. This includes images from "free beer" sites as Google Maps, and printed paper maps, even if you scanned them yourself. Commercial aerial/satellite photography is also copyrighted.

You should not use copyrighted maps in any way while editing OpenStreetMap (unless it is compatible with our license). "Using" includes tracing over the map, copying a name from the map, or pinpointing a coordinate on the map. To be on the safe side, we tend to regard all of these as a form of copying, or "creating a derived work". Generally speaking, it's best not to even look at copyrighted maps while you are editing OpenStreetMap.

So what can you use? Not very much, which is why we are doing all this re-surveying from scratch. However there are some Potential Datasources, in particular we have imported TIGER data for the US, AND Data for the Netherlands. We also make use of out-of-copyright maps although they are very old, and aerial imagery from Bing and Yahoo! Aerial Imagery (which we have special permission to trace over).

Can we import geocoordinates from Wikipedia?

Wikipedia articles are often geocoded, and it has been suggested a number of times that we should import data from Wikipedia (for example, using the pages on villages in a particular country to add place=village nodes). However, a substantial portion of those coordinates are derived from Google Maps. Wikipedia, which operates under U.S. law (where their servers are), considers facts like coordinates as non-copyrightable. OpenStreetMap operates under UK and European law, which gives special protections for databases and collections of facts, such as Google Maps and Google's data. Because of this lineage of the Wikipedia coordinates, the data is considered tainted as far as OpenStreetMap is concerned, and it is an established principle in OpenStreetMap that we don't import geodata from Wikipedia.

I uploaded my GPS track. Now it says "PENDING" and the queue's eight hours long. What gives?

At busy times, especially weekends, there can indeed be a wait before your track is added to the database. But you don't need to wait for this to start mapping.

If you're using Potlatch, find the 'edit' link to the right of your track (in the GPS traces listing), and click this - not the usual Edit tab at the top.

If you're using JOSM or another offline editor, just load the track from your hard drive.

I have just made some changes to the map. How do I get to see my changes?

Because map images take a little while to render, the map tiles are cached, and only updated on a periodic basis, rather than immediately after you edit it.

The default map (the Mapnik layer) tends to be updated after around one hour. When you try to view the map for that area, it will flag the area to the rendering software. Please keep in mind that "tiles" at particular zoom levels are not updated all at once. Therefore during the update period you may see your changes at some zoom level, while at another they will be visible after a while.

Alternatively you can choose the Osmarender layer. Select this using the + icon at the top right of the map. The Osmarender tiles are updated by many OSMers using their own computers (Tiles@home), which has results in different response speeds - usually less than one hour. If, for some reason, it doesn't notice your changes, you can go to informationfreeway.org; zoom into the area you want, at zoom level 12 (you'll see a 12 at the bottom right); hover over the relevant tile, when a dashed border will appear; and press 'R' (for "render"). It will then be added to the list for tiles@home computers to render.

If your data is still not appearing and you are pretty sure that the one or the other renderer has done its job, then you might have a tagging problem. Check that:

  • all your ways are tagged with something appropriate that will be rendered (eg highway=unclassified)
  • your tags are in lower case: HIGHWAY and Highway will not work.
  • you have underscore '_' and not a space for tags such as highway=bus_stop

What shall I do for roads that have multiple values for a tag?

Where different tag values apply to different sections of a road, we always split the road up into several ways. Something you think of as a single road, does not need to be represented as a single way. Splitting a road up into many ways is normal mapping practice. e.g. for short sections where bridge=yes applies, or sections of road with different maxspeed=* values.

If you worry about how to represent the whole length of road, you might look at using relations to re-group ways. WikiProject Europe/E-road network gives some examples of this.

If you have multiple different values for the same key, applying to the same element, then you may need to use the semi-colon value separator. For example, nat_ref=B500;B550 for a section of road that is designated both B500 and B550.

What makes a road belong to a city?

This is often asked by beginners.

Ideally, an administrative border (boundary=administrative) should surround the place. This makes it easy to automatically determine "where" every place is.

The Karlsruhe Schema lets you define which postcode and postcode-area-name each way or house has.

For many areas, the information on where exactly the administrative border is, is not freely avalible to use for OSM. A common fall-back method is then to use the nearest place=* nodes.

An alternative can be a closed way marking the extent of the city with place=* and place_name=*, as well as a single node with a name=* and place=* to mark where to draw the city-name. See place=* for details. For exceptional cases an is_in:city=* can be used, but there is less and less support for it (if any).

Another user has changed something I drew. I think they're wrong. How do I contact them?

To find the name of the user who last edited an object,

  • In Potlatch (the Edit tab on the web site), select the way and press H for history.
  • In JOSM, click the way look in the Author's panel (use the button in the bar down the left side or CTRL-A to make this visible if not already)
  • In the Slippymap on the OSM home page, use the + button on the map and check the checkbox on Data. Then, the data panel will be show on the left side of the map. Click Load data and wait until the features on the current data are shown on the map. Click the feature of which you want to know the history. It shows all the properties of the feature on the data panel and a link 'Show history' at the bottom of the data panel. Click the Show history. Finally, you can get the user name of the person who last changed that way. Farther, by clicking the Detail link on the history tab, you can get links to the user pages of all the authors.

You can then go to their user page. For Potlatch just click the 'Mail' button in the window that appears when you press H. Otherwise, for a user called (say) Fred28, go to http://www.openstreetmap.org/user/Fred28 and click "Send message" to send them a message. (This will not work in the rare case of anonymous edits)

You can use Potlatch's revert and undelete functions to restore the previous version of a way.

Incidentally just moving the position of a way means the node positions are changed: the way itself is unchanged.

How do I track edits of a region?

Sign up at ITO for OSM Mapper, define a region you want to watch and subscribe to the related RSS-feed.

Editing with Potlatch

See the separate Potlatch/FAQs page.

(Potlatch is the map editor that you get when you click the "Edit" tab on the main site. If you don't know which editor you're using, it's probably Potlatch!)

Editing with JOSM

See also the Josm Guide.

I tried to download my town/city/region - why doesn't it work?

Chances are the area you tried to download is too large, and the server probably timed out before getting the data to you. Try on a very small area first to make sure its working OK. If thats ok, then you are best to download the town in smaller segments. Presently, you cannot download an area larger than 0.3 degrees in either dimension.

If you really want large areas of data, the best approach would be to download the planet.osm file, which is generated weekly. This file is basically a snapshot of the OSM database and contains all valid data.

I want to create a very long way - how do I download OSM data for such a big area?

In order to be able to easily handle long roads, you should not make ONE long road out of it. You should rather split the road into several ways. As a rule of thumb, no way should be longer than 10-15 km. Typically, they will actually be much shorter.

Applications like route planners for example will be able to easily join the ways to one road again. This type of application will need to postprocess the OSM data anyway.

For motorways for example, it makes sense to make a way from one exit to the next. Also, intersections of motorways should be the point where you split a road into ways.

Why doesn't my login work?

There are two different logins for the OSM project: one is for this wiki only, and the other is for the website, API and forum. You need to register on the www registration page to actually be able to work with OSM data.

Using a GPS

Why didn't my GPX file upload properly?

Your GPX should consist of trackpoints with valid timestamps. The ele(vation) tag is optional and will default to 0. Note if using a Garmin GPS device: Many of these units have the facility to save the track that strips out the timestamps. Saved tracks will fail to be imported to OSM because of this. Instead make sure you upload GPX files created from the active track(s) from the device rather than any tracks you have saved.

The format for the gpx files as below is acceptable:

<?xml version="1.0"?>
<gpx
 version="1.0"
creator="GPSBabel - http://www.gpsbabel.org"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://www.topografix.com/GPX/1/0"
xsi:schemaLocation="http://www.topografix.com/GPX/1/0
http://www.topografix.com/GPX/1/0/gpx.xsd">
<time>2005-11-07T14:00:09Z</time>
<trk>
  <name>ACTIVE LOG</name>
<trkseg>
<trkpt lat="52.564001083" lon="-1.826841831">
  <ele>115.976196</ele>
<time>2005-11-07T12:03:31Z</time>
</trkpt>
</trkseg>
</trk>
</gpx>

GPX 1.1 will also work:

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<gpx version="1.1"
    creator="EMTAC BTGPS Trine II DataLog Dump 1.0 - http://www.ayeltd.biz"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://www.topografix.com/GPX/1/1"
    xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd">
<metadata>
<name>GPS Receiver track log</name>
<desc>Tallinn (car)</desc>
<author>
<name>Michael Collinson</name>
<email id="mikes" domain="ayeltd.biz" />
<link href="http://www.ayeltd.biz"><text>AYE Ltd.</text></link>
</author>
<time>2007-10-02T09:22:06Z</time>
<keywords>Estonia, Tallinn, A. Weizbergi</keywords>
<bounds minlat="59.4367664166667" maxlat="59.4440920666666" minlon="24.74394385" maxlon="24.7971432"/>
</metadata>
<trk>
<src>Logged by Michael Collinson using EMTAC BTGPS Trine II</src>
<link href="http://www.ayeltd.biz"><text>AYE Ltd.</text></link>
<trkseg>
    <trkpt lat="59.4408327" lon="24.74516185">
        <ele>44</ele>
        <time>2007-10-02T07:54:30Z</time>
        <fix>3d</fix>
        <hdop>300</hdop><vdop>300</vdop><pdop>300</pdop>
    </trkpt>
</trkseg>
</trk>
</gpx>

There are two things the importer won't do. First, it won't take in GPS points without timestamps as they're to be used to work out speed and so on. The other is that it doesn't import waypoints and your file consists only of waypoints. Opening and saving with GPX Editor will solve some problems. It can attach fake timestamps (anonymize time) if your file lacks them.

The reason for this is that if you reset many GPS units or download map data to them, then you often get copyrighted data put in the GPX. The most famous example is that if you reset a Garmin GPS unit then it will put the locations of the Garmin offices around the world as waypoints on the unit.

Tracks will fail to upload if data formats are not correct, for example my GPS setup occasionally throws in a NaN as an elevation value. Deleting those lines from the file fixes the upload.

Another cause of problems is ampersands "&" within waypoint names - e.g.

<wpt lat="-20.089861" lon="57.511535"> <name>The Grand Mauritian resort & spa</name>

Won't work, giving a "Generic XML parse error" but:

<wpt lat="-20.089861" lon="57.511535"> <name>The Grand Mauritian resort and spa</name>

Will work fine.

Another reason for import failure may be on the server-side. Please consult the platform status page to see whether a technical problem is known that prevents even correct gpx files from being imported.

I made a GPX file with a utility for M-241,but I failed to upload the file

Utility(HoluxLoggerUtility.exe) which attached M-241 has ability of generate a GPX file. However, I can't use the GPX file which I generated with this function in OSM. Because it's format isn't distinct from the format that explained in a previous paragraph. I convert it with another utility called GPSBabel to convert GPS log of M-241 into GPX. Concretely speaking, in GPSBabel,please set:

  • Input Format
    Google Navigator Tracklines (.trl)
  • Output Format
    GPX XML

So,It can convert correctly.

Why are the points on my tracks spaced out?

This is due to the GPS device (usually a Garmin) being set to record on 'Auto', which saves space by recording fewer points on straights. It's not usually a problem in rural areas, but isn't much use for city mapping. To make the GPS record more points, go to the track settings menu on your GPS, and change the recording method to either 'Time', or 'Distance'.

Time: Time will record points every 'x' seconds/minutes/hours. This can be changed on some GPS devices. Having this setting will use up the memory fast, but will increase the points considerably. The disadvantage of this method of saving is that when moving slowly with the GPS device the points will become densely packed. For example, many Garmin GPS's have a maximum tracklog capacity of 10,000 points. (Note that some devices also allow a log to be stored on a memory card in addition to the regular tracklog.) Setting a time interval of 1 second normally gives close to 3 hours of mapping (always a few points are not written due to errors and satellite availability). For fast road driving a 1 second interval gives very good trace information. The 1 second interval also works well for cycling in urban areas. For walking the rate can be decreased without loss of track definition to 2 or 3 seconds. The interval can also be increased when the mapping time needs to be extended but try to avoid unnecessary time intervals. You can change the time interval on the fly, useful if you decide to stay out longer than planned. If your GPS-Unit doesn't impose you serious restrictions on storage capability experienced mappers generally use a setting of 1 point/s to get best results in all mapping conditions.

Some advantages of the time setting are that relative speed can be judged by the spacing, There are more points when you slow down for curves or turns and less on straightaways where you need fewer points.

Distance: Distance will record points every 'x' meters/yards. This can be changed on some GPS devices. Having this setting will use up the memory fast, although relative to your speed. The disadvantage of this method of saving is that when travelling on straight roads fast, (motorways/highways), unnecessary points will be recorded. Also if you are to be tracking a small area, if the 'x' value is too high, your route will be unclear. In general distance recording can miss the subtleties of curves and direction changes, especially in urban areas.

Wrapping: If the option is available to turn on, or off the wrapping function, then having it off is also advised. Having wrapping on means that when full, the GPS device will make room to record the latest section of your route, by deleting the beginning of your route. It will delete the beginning, point by point, at the same rate as new points are created. The exception would be when you are logging track data to a data card in some Garmin models. The beginning data will be deleted from the device's built in memory, but not from the data card.

Why do I get bad signal / traces in city centers / near big metal buildings?

For a GPS to work and achieve some accuracy it needs to receive at least three satellite signals. Often when in city centers there are many tall buildings that can block these signals and stop the GPS from being able to work out where it is. There may also be multi-path effects from the material making up the buildings around you, whereby signals bounce off them so the receiver actually thinks it is somewhere in the buildings around. Another factor that can affect this is the number and position of satellites that can be seen at the time of logging; trying the route on another day or a different time of day may give better results.

What GPS should I buy? Can I use a "satnav" in-car unit?

See GPS reviews. Some in-car units will generate the tracklogs that OSM use, but you must make sure you turn off the "Snap to Road" option - otherwise your tracklog will be linked to the copyrighted map in your satellite navigation system.

How can I download this data and put it in my GPS ?

If you have a Garmin unit, see OSM Map On Garmin. Several users provide ready-made Garmin format maps for you to download and copy to your GPS.

Using OSM maps and data

How do I link to a particular postcode on OSM from my own website?

You can link to the search page for a particular postcode:

http://www.openstreetmap.org/geocoder/search?next_controller=site&next_action=index&query[postcode]=AA1%201AA

How do I link to a particular latitude and longitude on OSM from my own website?

You can link to the slippy map with a specific latitude and longitude and zoom level:

http://www.openstreetmap.org/index.html?mlat=[latitude in degrees with decimals]&mlon=[longitude in degrees with decimals]&zoom=[zoom level 1-17]

Coordinates must be positive for North and East, negative for South and West. For example, 28° 44' 16.09"S would be mlat=-28.737803 and 24° 45' 49.33"E would be mlon=24.763703 (that's Kimberley, South Africa, in case you're wondering).

Zoom levels: 1 = full zoom out, 17 = full zoom in.

Or link to a static image

How can I display maps on my website?

The easiest way is to use static data, i.e. to export data (using the 'Export' tab) and put it onto your website.

For dynamic display there is a Google Maps-like Javascript API; see the Export page on this wiki.

Can I download a vector map?

Use the 'Export' tab to download in SVG or PDF format. If you need other formats, see the Export page on this wiki.

Why doesn't 'Export' work?

On Wednesdays, the rendering database is reloaded from the main map database. This means the rendering database (used by Mapnik) is temporarily unavailable for the Export feature.

You can export an Osmarender/Tiles@home image instead, or wait until the database has finished reloading.

We aim to fix this in the medium term.

Where can I find software using OSM data?

For current software using OSM, see the Software page or its category, and also neat stuff for more experimental ideas.

For a more development-related angle, see Routing (and its category), the Beginners Guide topic on usage, and the Developers' pages.

Developer questions

Why should I not begin development on a new editor, one better/different/prettier than current editors?

There are already several very useful OSM editors in development, and confusing the space with "yet another" platform will only duplicate effort. Please consider contributing to one of the editor development efforts already in progress, such as JOSM, Merkaartor, or Potlatch.

Why don't we spread the load on the OpenStreetMap database across a number of servers?

Sharing the OSM server load via MySQL replication, or BitTorrent, or carrier pigeon is often recommended, but the idea has so far gained little momentum -- in terms of real development effort. If you have the system administration or coding expertise to implement such a distributed system, please do not hesitate to volunteer on the mailing list.

As a starting point, you may want to familiarise yourself with the existing software infrastructure, as described in the Development pages.

I think I found a bug, what should I do?

If you find a problem with the map editing applet or the website, add it to the OpenStreetMap bug tracking database. We use trac, which uses your OSM username and password.

If you notice something incorrect/missing/wrong/unintelligible with the documentation you're reading right now, edit it! It's a wiki! For wiki advice and extensive documentation, see the mediawiki project, who created the software this wiki is running on.

Can I write a script or bot to automatically edit OSM data?

If you wish to script changes to the OSM database then you can do so using the API. However, as such scripts can be very damaging if not done correctly, please read the Automated Edits page and the associated Code of Conduct for some good advice before you start.

Questions from GIS people

What geographic datums are used in OpenStreetMap?

OpenStreetMap uses the WGS 84 lat/lon datum exclusively. All uploaded tracks and edits should always be in WGS 84, the default datum for GPS receivers.

What is the map scale for a particular zoom level of the map?

The following table shows the nominal meters per pixel for each zoom level at three latitudes, and the equatorial scale on-paper assuming a 72 DPI printout. At other latitudes, divide equatorial figure by the cosine (eg: for London at latitude 50 divide by 0.64).

In the table below the "scale" column is rounded for readability. For example the nearest equivalent to an 1:50,000 map is zoom level 13 (nominally 1:54,000 at the equator, but 1:27000 at latitude 60).

Data from http://labs.metacarta.com/osm/

Table of Levels/Scales
Zoom level Scale at 72dpi (equator) Meters per pixel (equator) Mpp at 45 degrees (Milano, Lyon, Zagreb) Mpp at 60 degrees (Stockholm, Oslo)
18 1 : 1,693 0.597164 0.844525 1.194329
17 1 : 3,385 1.194329 1.689051 2.388657
16 1 : 6,771 2.388657 3.378103 4.777314
15 1 : 14,000 4.777314 6.756207 9.554629
14 1 : 27,000 9.554629 13.512415 19.109257
13 1 : 54,000 19.109257 27.024829 38.218514
12 1 : 108,000 38.218514 54.049659 76.437028
11 1 : 217,000 76.437028 108.099318 152.874057
10 1 : 433,000 152.874057 216.198638 305.748113
9 1 : 867,000 305.748113 432.397274 611.496226
8 1 : 2 million 611.496226 864.794549 1222.992453
7 1 : 3 million 1222.992453 1729.589100 2445.984905
6 1 : 7 million 2445.984905 3459.178199 4891.969810
5 1 : 14 million 4891.969810 6918.356399 9783.939621
4 1 : 28 million 9783.939621 13836.712800 19567.879241
3 1 : 55 million 19567.879241 27673.425598 39135.758482
2 1 : 111 million 39135.758482 55346.851197 78271.516964

See also http://almien.co.uk/OSM/Tools/Scale/

Why aren't you using Open Geospatial Consortium (OGC) schemas and software for OpenStreetMap?

There are many existing tools which people often recommend for OpenStreetMap to use. The problem is, most of them are hard to use and maintain for a variety of reasons, and people are very reluctant to volunteer to help set them up and run them. We used to use MapServer for serving static versions of our maps, but unfortunately we found it to be unthreaded, slow and hard to extend - we replaced it with Mapnik.

It's not that OpenStreetMap as a community is against OGC standards, but OpenStreetMap has been built iteratively using the simplest approach that could possibly generate useful maps. The focus is on street data and maintaining a 'wiki' approach to editing where all changes are logged and can be rolled back. Off-the-shelf tools don't support that in the way we'd like.

Help is needed on choosing which OGC tools and standards to use, and integrating them effectively into our existing systems. Please get in touch if you can spare the time and expertise to do this.

Also, see Why not GPX? for a similar discussion about why GPX was rejected as a transport format.

I have geo-referenced photography/shapefiles/waypoints for my area, how can I upload them?

We'd love your high resolution geo-referenced aerial photography/satellite images if they are free of copyright restrictions for derived works, or you are the copyright holder and can grant us the relevant rights - get in touch via the mailing list. You can also contribute your imagery to OpenAerialMap, which is available as a background layer in Potlatch, Merkaartor and JOSM.

For shapefiles and other data formats, again, get in touch via the mailing list.

What Geotagging do you use?

See Geotagging.

Admin

How can I close my account?

Contact a sysadmin, the sysadmin will disable your account and remove your details from the OpenStreetMap database. Your email address will usually be retained in the event that an OpenStreetMap sysadmin needs to contact you in the future.

If you have made any modifications or additions to OpenStreetMap, the sysadmin will ask you to license these under any future OpenStreetMap Licenses or to release as public domain.

Help - someone keeps deleting/reverting my edits. What do I do?

Please see the disputes page for details

I think someone's been entering copyrighted data - how do we deal with that?

If you find data that you suspect may have been copied from a copyrighted source or imported from a copyrighted source into OpenStreetMap without the owner's permission, please:

  1. Contact the user via using the 'send message' link from their user page (i.e. "www.openstreetmap.org/user/[user-name]") with the evidence. Be polite: it is important to remember that you might be wrong, they might have permission or it could be a simple misunderstanding. See Contact for more information.
  2. If there is no response (after 5 days) or you are deeply unconvinced by the response, email your evidence to the OSM Foundation so that the problem can be investigated.
  3. It may be that your report will be posted to the legal-talk mailing list (or a country specific list if this is more appropriate) for discussion - if so, you will be informed so you can join the discussion.

I am a copyright owner and my content is being used in OpenStreetMap Without Permission

  • If you are the copyright owner or represent the copyright owner, we can assist you directly by e-mail. You may contact us at data@osmfoundation.org with an informal request. Please cite the exact content in question. Correspondence is answered by a small team of volunteers.
  • This address is not for requesting permission to copy content from OpenStreetMap.
  • If you prefer to use or make a formal OCILLA request, you can send it to our designated agent. Digital Millennium Copyright Act Notice