[OSM-talk] Can I say "yes" to the ODbL if I can't account for 100% of my data?

[Tobias Knerr]

Steve Bennett wrote:
> On Fri, Jun 17, 2011 at 3:00 AM, M∡rtin Koppenhoefer
> <dieterdreist at gmail.com> wrote:
>> You can also put this information in the change-set-comment. IMHO this
>> is where this belongs to. AFAIK the source-tag is disputed and it is
>> recommended to use the changeset comments.
> 
> Source is disputed? By whom? I've never heard any dispute about it?

Source is very much alive. It has been suggested to use the source tag
on the changeset instead of every single object edited within that
changeset, but it's admittedly still mostly used the "traditional" way.

> I put a source tag on every single object I create, and try and update
> it when I modify it. IMHO changeset comments really don't work well
> (in Potlatch at least), and it's far too easy to include the wrong
> objects in a changeset.

I put source tags on changesets now. Source tags on objects tend to get
outdated, and I find updating all these tags painfully tedious. When you
add new objects, it would at least still possible to mass tag them with
your source, but that isn't possible when you have to insert your
sources into an existing source tag's value. It seems like unnecessary
effort, too, because I tend to group my edits into sensible changesets
anyway and rarely use more than one source for each changeset.

In my opinion, changeset-based sources also make it clear which edit was
using which source. For example, since good Bing imagery has become
available, I've developed a habit to trace the buildings in an area from
Bing, then go out and survey the area in order to add house numbers and
other attributes to the buildings (and make sure that the imagery wasn't
bogus).
This means that I will upload two changesets: One based on Bing, one
based on survey. Looking at the history and the source tags on
changesets makes it completely clear what data originates where. This
wouldn't work with a source tag on the object: A source=Bing;survey does
/not/ tell you that addr:housenumber=72 was surveyed and roof:color=red
was determined by looking at Bing images.

-- Tobias Knerr