I’ve just finished a cleanup and validation of field survey data collected in Bangassou, Central African Republic as part of the Missing Maps Project. I drafted a procedure for the global validation of OSM projects. I would love some input from others who have completed similar projects so I can refine the procedure and publish on the OSM Wiki.
Global Validation of a Project Area
- Define the area to be validated – this will ideally be predefined in a gpx file
- In JOSM, open the gpx file containing your area border
- Zoom in to an “acceptable” size area and click File–>Download from OSM. Make sure the “Download as new layer” box is checked. There will be a message in the bottom right corner of this screen telling you if the area selected is too big for the server. Sometimes it will say the size is okay, but you will get a server error when you try to download – this means that the area was too big and you need to try again with a smaller area.
- Once this is downloaded, go to a different area within your border and repeat with the “Download as new layer” box UNCHECKED. Do this until OSM data is loaded for your entire area.
- Go to Imagery and select the appropriate provider for your project (usually Bing)
- Scroll across the map and trace broad areas of problem imagery (low resolution or obscured by clouds). Tag the problem, the imagery provider and the date, like “name=low-res Bing image border as of August 4 2015”
- Check major roads for tagging consistency. Refer to the OSM wiki for guidance on tags. Highway Tag Africa and individual country pages are helpful.
- Look at the list of villages by going to Presets–>Search for objects by preset–>Geography/Places/Village
- Scan the list to identify naming issues, tagging issues, duplicates, or other errors. For example, you may see “Village” as part of the name, a village split and labelled 1 and 2, spelling variations for the same village, or overt spelling mistakes.
- Repeat for other features as needed, also checking the Tags/Memberships panel for consistency
- Make sure all villages have limits traced using landuse=residential (not name=residential) and that the whole village area is a single object rather than having neighborhoods traced separately.
- Run the validation tool within JOSM and address the problems it finds
- Upload changes to OSM