OSM: Common Errors and how to fix them
On this page, I describe some common errors I found when working on OSM data and how to remedy them.
The tool of choice for all advanced edits is IMHO [JOSM].
Double nodes/ways as a result of duplicate upload of data
Sometimes people seem to upload data twice. Be it because the first upload seemed to be unsuccessfull, be it because they don't realize it... the result is the same: Lots of "duplicate nodes" as can be seen on [Matt's Duplicate Node Map].
Removing a duplicate upload
Before you can remove a duplicate upload, you have to identify it as such! What I usually do is:
- Load the area in JOSM
- Run the validator plugin
Now, if the validator shows a big number of "overlapping ways", chances are, there is a double upload of data.
Identifying a double upload
- In the validator result-window open the branch "Errors -> Overlapping Ways"
- Double-click on any entry, then hit CTRL+i to show the details of the two ways in your browser
- Your browser will load two new pages, showing the details of the tow ways
- In each of these windows click on the Changeset number
Now you see the two changesets that produce the "overlapping ways".
Here comes the crucial step: Use your brain!
Removing a redundant changeset
Once you are certain that one changeset is redundant:
- change back to JOSM
- open the search-window (CTRL+f)
- enter "changeset :" followed by the number of the redundant changeset
This will select all the data from that changeset. Now you can take a deep breath and hit DEL to remove it.
