When we are working with JOSM and about to upload the changes, sometimes we encounter this message:
This happens when you download a group of data that includes a particular point, let’s say point A. At the same time there are other people who also downloaded point A, making changes to it and upload it back to OSM. Now when you try to upload your changes (including point A) with your version, the version is already different from the server version. This causes the server to be confused on which version of Point A that is correct.
The process of resolving conflicts in JOSM is pretty simple, even though it might be confusing at first. Basically, all conflicts that occur in JOSM will leave you with two options – Your Version of the object and Their Version of the object that is on the server. You just need to choose which version you want to use, -your version or the new version in the server.
located. Conflict in this example indicating that it is on the properties, such as location or the object’s position. You can see that the coordinate and state are deleted.
Types of Conflict:
Conflict just shows up on two different edits at the same time. If there are three or more different edits happen at the same time, chain of conflicts will occurs. You can only solve two conflicts at the same time. You can choose Your Version, Their Version, or merge the two changes.
In this example, you don’t have option to merge the changes. Click on the My Version column if you are sure that your version is the right one. Click on Their Version if you think that other mapper’s edit should be retained.
This window displays a list of conflicts. The total number of unresolved conflicts is shown in the header. You can select or resolve a conflict by clicking on it. This is useful when you have many conflicts to deal with.
To minimise the chance and number of conflicts it is important to upload your edits regularly. Conflicts appear more frequently for those who tend to save the area they are working on in their local computer, but wait a while to upload their changes. It is best to download the area you are working on, edit it and then immediately upload it. The longer the time between downloading data and uploading changes to that data, the more likely it is that someone has edited something in the meantime.
Editing in the specific area you have downloaded minimises the risk of conflict. Make sure you do not edit outside of the area that you have downloaded. You can easily see the areas outside your download area in JOSM, because the background is made up of diagonal lines instead of being solid black.
The OSM Tasking Manager is a tool that mappers can use to sort an area into a grid, and work together to map in an organised way. Apart from being more organised, the tasking manager is also one way to avoid editing conflicts, because it helps prevent more than one person from editing the same area at the same time.
The way the tasking manager operates is every mapper on a project selects one box from a grid overlaid on the mapping project area. This box represents a subsection of the mapping project area. When a mapper finishes mapping all features in their box, they can mark it as complete. This way, a team distributed in different areas can coordinate and work together to finish mapping in that grid.
To see how tasking manager works, let’s practice a bit more.
- Orange box represent an area that already mapped
- Green box represent an area that already mapped and validated by other people
- Orange outline box represent there is someone who currently map in that area
- Grey/empty box represent the task is unfinished.