This course will become read-only in the near future. Tell us at if that is a problem.

An OpenStreetMap How-To


Excerpts from OpenStreetMap Chat
Getting Started

What is OpenStreetMap?  Go to to get started. Then keep reading.
<ndoiron> on OpenStreetMap click the Permalink to link to your view
Editing the Map with Potlatch 2
To make edits:
Register an account on OpenStreetMap, then go to Account Settings to set Preferred Editor to Potlatch 2, then click Save Changes at the bottom of the page
Now as you explore OpenStreetMap, while zoomed in and signed in, you can click the "Edit" tab to make changes.
<trekr5> @ndoiron what's potlatch2?
<Sharonm> @trekr5 The default editor on the Web site is potlatch 1
<Sharonm> but you can change it to potlatch 2
<Sharonm> which does indeed seem easier, as @wwilson suggested
<berniejconnors> Potlatch is loaded when you click the "edit" tab on the OSM website
<alex_> Potlatch offers more options
<alex_> nick, with Postlatchthe images are better (at least the zoom), and you can edit the vertices (moving) or adding more as wwilson said
<rrosso> How do I get a permalink that shows my edits?
<ndoiron> Go to your user edits page
Satellite Maps can Help, but not all are Open
<berniejconnors> @rrosso you don't collect coordinates from other online maps
<berniejconnors> @rrosso you either collect GPS tracks with a handheld GPS or you digitze streets from the air photos that are displayed in the OSM editor
<ndoiron> @rrosso you draw it in the Edit tab
<wwilson> @introvert Satellite or aerial photography.
<wwilson> If you're using the online editor, they'll automatically display the best they have in your region.
<wwilson> US is mostly Yahoo and Bing.
<wwilson> @trekr5 There are other imagery providers outside of the US.
<rrosso> I'm confused about what we can/can't do with Bing/Yahoo mapsUsing lat/long data from Bing is copyright infringement, someone said.
<ndoiron> @trekr5 OpenStreetMap is open for others to reuse, sell, and download The references have to give permission or be open maps themselves
<rrosso> So what did Bing just start allowing people to do a couple months ago that enables one to use it with OSM?
<ndoiron> @rrosso  They allow you to trace roads from their images into OpenStreetMap
<ndoiron> @rrosso  the best tracing program to start with is Potlatch, which is on the site
<rrosso> @trekr5, @ndoiron: is Bing better than google maps for that sort of thing?
<ndoiron> Google doesn't allow it
<rrosso> @ndoiron: I guess that makes Bing better for it, huh? :)
Adding Tags and Labels
<alex_> Just register to OSM, make a little edit  -  How do you label 2-way streets?
<ndoiron> alex_: I did some Googling, maybe you can do oneway=no ?
<alex_> Thanks Nick, it worked fine (once you know what to do)
<Sharonm> Am finding OpenStreetMaps a little frustratingI just tried to add a post office, and it's asking me for the post office reference numberNo idea how to find that, USPS Web site doesn't have it that I can see.
<wwilson> @Sharonm I don't think tags like that are mandatoryThough they are, of course, useful.
<wwilson> @rrosso Not sure it has meaning in the USSee:
<wwilson> Remember that OSM is international, so not all tag are applicable in all countries.
<berniejconnors> Yes OSM is international I had a hard time calling a soccer field a "pitch"
<wwilson> None of the post offices I've looked at in the US have ref= set, but I'm new to this, so who knows?
<introvert> ndoiron: is it OK to identify (with what?) early childhood buildings for a particular service provider?
<ndoiron> @introvert Tag the school as an "amenity" that's type "school", and you can add more tags like grade level
<ndoiron> for people who've used OSM longer :  do the tags and values have a good standard?  Or is it just important to put what you know
<berniejconnors> I find there is usually a core of OSM users in your community / country who try to suggest standards for tagging.
<alex_> I think your localiy knowledge is what counts
<berniejconnors> Personally I find adding the geometry is the most important
To Fix and Add Streets and Buildings
<berniejconnors> @rrosso here is a quick video I just made of digitizing a building:
<Sharonm> How do I add a street? There's a new street in the area, I see it on the image but it's not on the map yet.
<alex_> sharon just click on one end of the street and keep adding points, finishing with a double click, then add data in the left panel
<berniejconnors> It is best to save after just a few edits becuase it can be slow when you have made many edits
<Sharonm> Not sure how to add geometryI'm just adding points of interest, which is the knowledge I already have -- adding points to maps.
<alex_> Sharonm just click on the map without dragging any tag, then you should add more points, and double click to finish the line
<Sharonm> What's easy to start with?
<berniejconnors> @sharonm  A building footprint or a short residential street is a good easy place to start.
<wwilson> @Sharonm There are plenty of spots where if you compare the roads with the photos, it's clear that the OSM data is misaligned. Just dragging stuff into the right spot is an easy way to get started.
<wwilson> Don't know if that's a problem in your area, but it's really bad in, for instance, SoCal, Arizona, and New Mexico.
<Sharonm> @ndoiron But I only need to reclassify part of the way How do I select just part of it?
<Sharonm> I'm trying to select just a piece of a way but can't.
<ndoiron> in the bottom right, do you have a scissors?  it can split the way and then you could rejoin the two halves
Deleting Points
<DoRight> @bernie How do you kill a point?  I clicked by mistake in the editor and couldn't get it to stop.
<rrosso> @DoRight: I did the same thingI think you can select it again and hit the red X in the bottom-right toolbox to delete it.
If there's already a high quality map, what should I edit?
<introvert> ndoiron: what if I don't see anything to edit?
<ndoiron> you can look at more places that you know, and add building outlines or more obscure things
<berniejconnors> introvert: It is not important to know the name of the building right now Just digitize the outline You  or another user can add the tags later.
<berniejconnors> introvert:  Mappers from all over the world digitized the streets of Haiti following last years earthquake Most of them did not know the street namesBut eventually somebody added the street names.
<berniejconnors> introvert:  Don't sweat it - just give it a try What ever you do can be undone.
Making Interactive Mashups (later)
<trekr5> @ndoiron are you going to show us how to create a basic mashup using OSM data in this course?
<ndoiron> @trekr5  yes, interactive maps are next after OSM
Assignments / Tasks
<trekr5> should we have completed the assignment - adding point of interests to OSM map - before we come to this class?
<ndoiron> @trekr5   nope we're signing everyone up now had you used OSM before?
<rrosso> Do we have an assignment before the next session?
<ndoiron> @rrosso if you're interested in adding more complex things, you can look up your country / local page on the OSM wiki, or helping others map

Task Discussion