Editing Your Own OpenStreet Maps

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Raw geographical information is not the only data source that is available to you. Clicking the Imagery menu item gives you a menu of possible data sources where you can download geographical images. You can change this list by clicking the Imagery→Imagery Preferences menu item and selecting the sources you want to use.

Figure 4. You can select the data sources used for downloading geographical imagery data.

In Figure 5, I selected the Imagery→OpenStreetMap Carto (Standard layer) menu item to get the cartographic imagery for my map area. You can choose the layer you want to work on by selecting it in the Layers pane at the top of the right-hand side. You also can change the order in which the layers are stacked or change whether they are visible. If you have your own imagery available, you can click on the Imagery→Rectified Image menu item to select the server from which your imagery is served.

Figure 5. You can add multiple layers with satellite imagery or cartographic imagery.

What I have covered so far is fine if you just want static maps of pre-existing data, but that isn't very interesting. The last bit of functionality I want to cover here is how to add your own data to these maps.

You can add nodes, or a series of nodes, by selecting the appropriate tool from the list of icons at the top of the left-hand side. When you add a node, you can tag it as a particular type of node or group of nodes. You can access several preset types by clicking the Presets menu item. These presets include natural objects, man-made objects and lots of geological features. This allows you to start adding tracks, objects and other features that are based on local knowledge, which means that you can create very specialized maps of your area.

Clicking the Edit→Preferences menu item brings up the preferences window for JOSM. You can tweak several options to change how JOSM works. The Map Settings tab lets you change the main display options, such as the projection or the mapping styles available for use in JOSM.

Figure 6. The preferences window lets you tweak a lot of the functionality in JOSM.

Figure 7. The Map Settings tab lets you select and download alternate mapping styles for your map display.

As I mentioned earlier, a large selection of plugins is available from the community of JOSM users. You can access this library from the Plugins tab, where you can download and activate the plugins that interest you. Once you start looking at the available options, you'll see that there is a lot of extended functionality available for doing some serious work with your maps.

Figure 8. The Plugins tab lets you select from a large library of available plugins.

Once you are happy with a map, you'll want to save your work. JOSM can save all of the data related to your map in one of many different geographical file formats. Clicking on File→Save As pops up a save window where you can select from file formats such as GPX, GeoJSON or OSM Server Files. You also can upload changes back to the OpenStreetMaps servers if you are adding previously unknown information.

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Joey Bernard has a background in both physics and computer science. This serves him well in his day job as a computational research consultant at the University of New Brunswick. He also teaches computational physics and parallel programming.