Preparing for the field

Now you have a POSM. The device has all the core software ready to go, and the next step is to create a “deployment” - this means downloading all the OpenStreetMap data and other resources for your area of interest (AOI). You should do this in an area with a stable internet connection - if you are traveling for fieldwork, we highly recommend doing this before you leave. POSM can handle relatively large deployments (entire districts and sometimes countries).

Creating an AOI deployment

On your computer, when connected to the internet, navigate in your browser to the POSM export tool. This site will allow you to select a geographic area and extract the OSM-related data you need for it.

First, long in with your OpenStreetMap credentials. You’ll arrive by default at the “Create” page. You can set the area by searching for a place, by geographic coordinates, or by zooming in on the map and physically drawing a box around your project area.

Once you’ve entered in some basic project info on the left side of the screen, then click on “File Formats” in the navigation menu.

This tool was designed to enable a variety of mapping analysis and data uses, so you won’t need to check all the boxes - all that’s required for POSM is the OSM PBF file (the OSMAnd OBF is also highly recommended). But just in case, here’s a run-down of what your options are and what you might use them for if you do want extra data available offline:

  • Esri SHP (OSM Schema): Standard shapefile used by most GIS applications. This extracts all OSM data into three shapefiles (point, line, and polygon)
  • Esri SHP (Thematic Schema): Standard shapefile used by most GIS applications. This extracts the OSM data into many shapefiles (e.g. waterways, buildings, health/schools, residential landuse areas, airports, amenity points, etc). This is probably more useful if you are building a base map or need basic GIS data layers for the area.
  • Garmin Map: For loading onto GPS devices
  • Google Earth KMZ: For loading into Google Earth. Often used for tracks.
  • MBTiles: Background map tiles for offline use. Extracting these will allow you to host offline mapathons with the HOT tasking manager. Check this box and enter the Bing API when prompted: https://ecn.t2.tiles.virtualearth.net/tiles/a{q}.jpeg?g=587&mkt=en-gb&n=z. Make sure the {q} copies and pastes properly - it sometimes gets replaced with other characters. Once you’ve pasted the link, you’ll also need to set the minimum and maximum zoom levels; we recommend 13 to 20. Note: These MBTiles aren’t an effective substitute for the tiles needed in the OpenMapKit app; you will still generate these using POSM.

  • OSMAnd OBF: For loading onto the OsmAnd offline map app for Android phones. This app is really useful for offline navigation and wayfinding during fieldwork.
  • OSM PBF: This is the core OSM data package. This is the only absolute requirement for POSM.
  • OSM XML: This is unnecessary and will be removed from the listing shortly.
  • SQLite SQL: OSM data for working with in a database format

Once you’ve made your selections, run the export. This can take some time - you’ll get an email when it is complete.

You can download the individual components or the whole bundle, but the easiest way to get the export onto the POSM is by looking for the “POSM Bundle” download, right-clicking that, and copying the link. You will use this link to download the bundle directly onto the POSM.

Moving the AOI onto the POSM

Plug the POSM into an ethernet connection and power it up. POSM will broadcast a local wifi network named “POSM”. The password is awesomeposm.

Use your computer to connect to the POSM wifi. In your browser, navigate to posm.io (any http:// website will also redirect to posm.io).

Click on the admin console, then enter the URL from the “POSM Bundle” link in your data export (it will end with .tar.gz. Click “Start”. You will see text appear in the console output, letting you know it is running. Behind the scenes, POSM is downloding the OSM data and setting it up for use. This can take some time.

When the POSM extract is ready, you can unplug the ethernet cable - POSM has everything it needs to go offline.

Creating MBTiles

There’s one last thing you need to do to set up POSM. Go back to the posm.io homepage, and click on the FieldPapers link. You need to create a FieldPapers atlas for the area you’re working in - this triggers the creation of MB tiles, which are needed for an OMK deployment. These are the zoomable map tiles in the background of the OpenMapKit app; the OSM data sits on top of this as interactive buildings, roads, etc. It can take a couple of hours to create the MB tiles, but this can run in the background as long as POSM is plugged in and powered up.

Field Papers process:

Note: if you are doing repeat cycles of mapping, then every time you make OSM edits using OMK, iD, JOSM, etc, you will need to re-run the FieldPapers atlas in order to create updated MB tiles for your area. This means that your second and third round of mapping will build off previous changes.

What next?

This set-up procedure includes everything that must be done with an internet connection. Everything else can be run offline, but we highly suggest testing the entire workflow before going to the field to allow time for troubleshooting.