1

My state recently acquired several new property parcels that were added to an existing state park. I wanted to edit the existing OSM forest that exists to add these new parcels. I have access to the state’s parcel data. How do I add them to OSM? Do I need to upload them as GPS Traces? Or is there another way to upload a small number of existing shapes? (as a ShapeFile, GPX, KML, etc.)

I’m pretty familiar with GIS tools in general and I know my way around ArcGIS pretty well, but I’m new to editing in OpenStreetMaps.

4

It is possible to convert other geodata formats to OSM format and upload them via JOSM. However, license compatibility must be researched first. We can’t import data with an incompatible license into OSM.

If the license is compatible, one option would be to convert the shapefile to geojson since JOSM can open that format natively. The new parcel polygons could then be copied to a downloaded OSM data layer and merged with the existing boundary.

6

More detail:

  1. Make sure the license is compatible with OSM
  2. Make sure the data is unprojected and in the WGS84 datum
  3. Delete any parcels that you don’t intend to add to the state park in question
  4. Delete all attributes (fields). These are unlikely to correspond directly to OSM tags, and in any event, you will be using the tagging from the existing state park in OSM.
  5. Convert parcels to Geojson
  6. Start JOSM
  7. Download data from OSM in JOSM. If the state park is represented in OSM as a relation, download all members of that relation
  8. Open geojson parcel data in JOSM
  9. Merge the two layers (geojson parcels and existing OSM data). This just merges the two layers, it does not merge the individual geometries.
  10. Make sure that the existing state park and the new parcels overlap (unless of course, these new parcels are exclaves, in which case the process will be a bit different)
  11. Select the parcels in question and the existing state park relation/closed way
  12. In JOSM Tools → Join overlapping areas
  13. Make sure there are no “slivers” in the new geometry representing the state park (small bits of ground in the new state park that appear as holes or salients that don’t exist in reality)
  14. Address any other topological issues
  15. In JOSM, make sure nothing is selected and run the validator. Address any issues that result from your actions
  16. In JOSM, upload to OSM, providing a meaningful change set comment and citing your source(s).
2

You might get better answers if you tell us which state park you’re talking about, but I’ll try to give you general advice.

How do I add them to OSM?

Since you’re new to OSM, you’ll probably want to learn how to use iD, the browser based editor built into the OSM site. IMHO it has the gentlest learning curve of OSM editing tools and is the most accessible for n00bs. If you stick around as an editor, you’ll probably eventually want to graduate to something a little more advanced, which is where JOSM comes in. JOSM is a separate Java-based app designed for editing OSM.

Do I need to upload them as GPS traces?

No, you wouldn’t need to upload any GPS traces. OSM does store GPS traces, which are useful for some things, but state parks are represented by areas. To edit a state park in OSM, what you’d wanna do is add new nodes or edit the existing nodes that make up the polygon that represents the state park’s boundaries, which will change the shape of the area in OSM.

I’d recommend checking out the Beginners’ Guide on the OSM wiki.

3

I’ve reviewed the Beginner’s Guide and took a tour of iD and it doesn’t seem to answer the question of:

Is there another way to upload a small number of existing shapes?

I have the official GIS shape data from the state, I would like to upload it so the results will be precise. I could attempt to draw them in iD, but they wouldn’t be precise, nor would that be very efficient.

Hope that helps clarify the question.

5

This is a perfectly clear answer on the mechanics, thank you!

7

Awesome! Thanks for the additional detail! I do have exclave to deal with but I’ll probably be able to figure that out and, if not, i’ll ask here. Thanks!