Source key

Question

Some newly drawn buildings have just turned up on my local map and the source key has not been added. As buildings are rare in our location I've checked out buildings and other features in London and Munich and found this to be common. If I check an author's edit I note that often the source is mentioned in the comment. Is stating the source in the edit comment an alternative to adding the source key to the properties of the feature?

Answer 1

Generally putting the source on an object is not the best way to do it, as it creates a lot of entries that the next user would potentially have to modify when modifying the object. E.g. if there is a building and you are then attaching a usage or other amenity which occupies the building you won't be able to derive this information from aerial imagery. The better approach is to use changeset comments for source information. This requires that you group your edits into changesets with the same source though, but it ensures that the information is set where it applies to: to the edit.

Answer 2

When I have been using Bing imagery for building outlines, I use the tags source:shape=Bing for the outline and source=survey for the address detail etc

Answer 3

I've already read that adding the source on a changeset is an intesting solution for multi-sourced objects properties. But you can edit objects using aerial imagery and physical survey, and the problem is the same.

I've not found a clear and complete solution on documentation, but what is possible is:

use multi-source value by using a semicolon as a separator, for example source=bing;survey either on the object or on the changeset
for changeset sourcing solution: use strictly only one source per changeset. It may be sometimes difficult, but improve the traceability
for object sourcing solution: specify the source for each tag, considering that the default "source" is for the nodes. For example: source=bing for the nodes and source:name=survey

Answer 4

Putting the source on the changeset may be easier for you, but I think it makes it harder to trace back the source of particular bits of information as the object undergoes multiple changes. It also requires additional API calls (multiple GET /api/0.6/changeset/#id for every changeset in the history of every object you download).

For me, when I tag source=[imagery provider] this means that all the information came from this source.

If I want to combine multiple sources I make this clear using something like,

source=survey
source:location=[imagery provider]
source:[key]=[value]
...

This way you can explicitly tag the source of any tag using source:[key] I use source:location=[...] to mean the source of the coordinates of the nodes in this way. I also use source=[...] to mean either the source of all the tags with no individual source tag, or the source of knowing that this feature exists roughly at this location.

Using source=[provider1];[provider2];... can be problematic as it isn't always clear which parts came from provider1 and which provider2.

Source key

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