Introduction to JOSM

Terminology

Node: A "node" is a point.

Way: a "way" is a line connecting multiple nodes. "Way," therefore, is a general term for series of joined nodes, not just for roads or ways in reality.

Relation: A "relation" is an ordered sequence of ways and nodes, a logical container used to group elements.

Area: An "area" is a way whose ends are connected.

If a road or track or path is curved, the curve is approximated using a number of nodes within a way, and short lines connecting them. If a way has a direction, that is useful for a number of tags, e.g. "oneway=yes" is a road which goes only in the direction the way is drawn [Could someone please explain what this sentence means?]. Other tags refer to being on the left and right of the direction of travel along the way.

Starting JOSM

JOSM is a Java program, and comes in a .jar file. If you don't know how to start it, ask someone familiar with your platform how to run a Java program. You might also want to read the install notes.

When JOSM starts, it presents you with a few messages about recent changes in JOSM. You should have a look at this page from time to time as it keeps you informed on some of the more interesting changes.

Your next step should be to download some data. If you have a GPX file (downloaded from your GPS receiver) for the area of interest, load it into JOSM (File/Open). That will show you the area of the GPX file. Click on the green down arrow to fetch the data from openstreetmap.org.

An alternative is to download existing GPX points from the OSM server. In order to start this process you will need to know the latitude and longitude coordinates of the relevant area. The easiest way to do this is to use the download dialogues slippy map in the first tab. You can browse this map, zoom in and out and mark the area you're interested in. Read more on the download dialogue.

Editing in JOSM

JOSM is an offline editor which means everything you do won't be visible for anyone else until uploading it to the server. This makes it possible to experiment and repeatedly moving, tagging, adding and deleting elements without breaking anything. Subsequential actions on a single element will go into the database as a single modification when uploaded.

The first step of actual editing is to add a node to the OSM data where there will be a junction or a significant change in direction. To add a node, highlight the node button, either by clicking the 2nd button in the left menu bar, or by hitting the "A" key on the keyboard (the 2nd button should then be highlighted). Move the mouse cursor over your GPS track, and left click it wherever you want a node to be. A white dot (a selected node) should appear and a rubberline span from that dot to the mouse cursor. As you create subsequent nodes the earlier nodes will be shown as yellow dots.

A series of joined nodes forms a way.

Ways on their own are not of much use unless they are tagged to say what they represent. ​Map Features shows all the current key value pairs which could be used on a way. Ensure the properties pane is open on the right hand side of JOSM, the 8th button on the left (an icon with a wrench over a document) should be highlighted. If not click that button or hit "Alt+Shift+P". The properties pane has three buttons: a plus sign with "Add" next to it, then "Edit", then "Delete".

Editing properties refers to all the currently selected, i.e. highlighted, elements (nodes and ways). To select anything you must be in select mode which can be switched into by clicking the first of the left hand icons or hitting the "S" key. Ensure your new way is highlighted, then click the "Add" button, a dialog box will appear and you will be asked to select a key and a value. Type in the key/value pair which represents the way you are creating, e.g. for the key type "highway" without the quotes, and for value type "secondary" again without the quotes. Now click OK. You have now tagged your way.

Uploading to OSM

If you are happy with all that you have done then you need to upload this to OSM server. Click on the green up arrow .

JOSM will give you an overview on the elements it's about to upload. You're also asked to provide a short freetext summary of your edits. This description will be saved with your data on the server and serves information purposes like for example the ​Recent Changes list.

With a click on "Upload changes" your data will be uploaded and visible for everyone else.

See Upload to OSM for further informations on uploading.

Conventions

A couple of other points about creating ways.

1) Dual carriage ways should be drawn as two separate parallel ways, with each carriage way being a different way.

2) If a street is one way (including the individual carriageways of a dual carriageway) the way should be drawn in the direction of travel.

3) The key / value tagging is case sensitive, all keys should be entered in lower case.

---

Back to Main Help