The JOSM Editing Process
In the previous section you
installed JOSM and began drawing your first points, lines, and shapes.
You added presets to these objects in order to attach information about
them. By the end, you were able to draw your own map in JOSM.
This was good practice, and now we are ready to edit OpenStreetMap.
In this section we will take a closer look at the interface of JOSM, and see
how we can use it to edit the map on OpenStreetMap.
The Cycle of Editing
Editing OpenStreetMap with JOSM is similar to editing with the iD editor we
saw previously. But because JOSM is a desktop application, it works a little
bit differently. The process of editing and adding to OpenStreetMap with
JOSM will always be as follows:
- Download the current map data from OSM
- Edit it using Satellite Imagery, GPS, Field Papers, and notes as a guide
- Save changes to OpenStreetMap
Downloading OSM Data
The first editing step is to download the data for the area of the world that
we want to improve. Remember that you need to do this every time that you want
to make changes to the map, because the map is often being updated by other users.
- Click on “File” in the top left corner of JOSM and click “Download
from OSM”. This will open up the download window. You can access
this window more simply by clicking on the download button, shown
- When the download window opens, you should see a map. If you don’t see the map, click on the tab marked
- Use your mouse to pan and zoom it to an area
that you know very well, such as your hometown or neighborhood. The
controls are the same as in the JOSM map window. The right mouse button
lets you drag the map, and your scroll wheel allows you to zoom in and
Sometimes if you are working on a notebook computer it can be difficult
to scroll in and out. Working in JOSM is much easier if you have a mouse,
but most modern notebooks allow you to scroll using the touchpad.
- Draw a box around the area that you want to download. To draw a new box, click on the
map, hold your left mouse button down, and drag your mouse to create
a box. Release the mouse button to finish drawing the box.
- When you are satisfied with the size and location of the box, click
“Download” at the bottom of the window. JOSM will get the data for
this area from OpenStreetMap and open it in your map window for
If you followed along when we added our first points with the iD editor, you
remember that beneath the map data there was a satellite image that helped
us identify objects on the ground. This imagery was from Microsoft Bing, which
generously provides its imagery for OpenStreetMap users to reference while
contributing to the map.
- To add the Bing satellite imagery in JOSM, click “Imagery” on the top menu of
JOSM and selecting “Bing Sat.”
If you don’t see Bing Sat on the Imagery menu, you may need to activate
it in the JOSM preferences. Go to Edit -> Preferences and click on the icon
that says “WMS TMS”. You may need to click on the down arrow to find it.
Click on “Bing Sat”. Then Click “Activate”.
Tour of JOSM
Now that we’ve downloaded OpenStreetMap data and added the Bing satellite imagery,
let’s take another look at the interface of JOSM.
The main window you are already familiar with - this is the map window, and
it is where most of the action takes place. Here you will view, edit, and
add to the OpenStreetMap data.
To the right of the map window are a series of panels, each of which has
its own function. Typically when you first install JOSM several
panels are shown by default, such as Layers, Properties, and
Selection. When you select a point, line, or shape in the map
window, it will be shown in the Selection panel. Information about
the object will be shown in the Properties panel, and the username
of the author of that object will be shown in the Authors panel.
These panels can be opened or closed by clicking on the various buttons on
lower left side of JOSM. Above these buttons in the upper right are tools which
change what you can do with your mouse. You are already familiar with some of them,
the Select tool and the Draw tool. Below them are tools which make it easier to
zoom in, delete an object, draw a shape, or create a line that is parallel
to another line.
So we have completed step one of the editing process - Downloading. We have
prepared JOSM with satellite imagery as a reference. The next step is to edit
the map and add new items.
Depending on the area that you chose to download, there may be a lot or very
little existing map data. But notice that it is the same sort of data that we
have seen previously - points, lines, and shapes that represent real-life locations.
- Use the techniques you have already learned to add a couple points to the map
of places that you know. If you see any mistakes, try to fix them.
- You don’t need to be too aggressive while you are learning. If you are unsure
about something it’s better to leave it as it is.
- If you want to move a point, line, or shape, use the
select tool. Click on an object and drag it where it
should be. This can be used to correct the location of items that
have been put in the wrong place.
- Use the draw tool to draw new points, lines, and shapes.
Describe these objects by selecting from the Presets menu, as you
did in the previous section.
Never edit the map outside of the area you have downloaded. You
can see the rectangular area you have downloaded has a solid background,
while the area you have not downloaded has diagonal pinstriped lines.
The third and final step to complete our edits is to upload the changes we have
made to the OpenStreetMap database. To save the changes, we must
be connected to the internet.
- Click “File” on the top menu, and then click “Upload Data”. This
will open up the upload window. You can access this window more
simply by clicking on the upload button, shown here:
- The window that appears shows a list of the objects that you are
adding and the objects you are modifying or deleting. In the box at
the bottom you are asked to provide a comment about the changes that
you are making. Type in here a description of your edits.
Click “Upload Changes”.
- If this is your first time saving changes to OpenStreetMap, you will
be asked for your OpenStreetMap username and password.
- Enter them in the window that appears. If you check the box in
this window, your username and password will be saved and you won’t
need to enter them again in the future. Click “Authenticate”.
- You will need to wait a few seconds for your changes to be uploaded,
and then you are done! You have edited the map on OpenStreetMap.
When you are editing, always be sure to upload your changes before you close
JOSM. Even if you still have more editing to do, upload your changes, and
then go through the process again later when you have time to edit.
You don’t want to lose your work!
See your changes on the map
- Open your internet browser and go to http://openstreetmap.org/
- Move the map to the area that you edited.
- You should see your changes now appearing on the map! If you don’t,
try pressing CTRL+R to refresh the web page. Sometimes the map
doesn’t update properly and needs to be reloaded.
- What if you don’t see your changes? Don’t worry - it may take a few
minutes for the changes to be shown on the map. Also, check your
additions in JOSM to make sure that you added them correctly. A good
general rule is, if your point has an icon in JOSM, then it should
be seen on the main map at the OpenStreetMap website.
Now that you’ve seen how to add to OpenStreetMap, what’s next? Well, editing
is great, but it’s not the only aspect of making maps. Of course you also
need to learn how to go outside and collect information about places on the