[OSM-talk] Source tags and changesets (was ... ODbL ...)

[Ed Avis]

Tobias Knerr <osm <at> tobias-knerr.de> writes:

>I put source tags on changesets now.

That sounds like a great idea.  (Does Merkaartor have support for this?)
I do worry that people who've grown accustomed to seeing the tag on each object
would be less happy at having to dig through the object history.  Do some
OSM editors have convenient support for clicking on an object and seeing at
once all the changeset tags that apply to it at the same time as the object's
own tags?

>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.

People have developed elaborate schemes like source:name which in principle
could be extended to source:roof:color=Bing.  But it seems silly to do this
manually when it could automatically be determined from the changesets.

This is not really a technical question but one of convention: are per-changeset
source tags generally accepted practice in the project these days?  And is
there a way to retrospectively add tags to existing changesets?  (I have always
noted 'Bing' or 'OS' or 'mapping trip' in the changeset comment but it would
be nice to go back and tag this in machine-readable form.)

What follows is general fat-chewing about how we map.

>I tend to group my edits into sensible changesets
>anyway and rarely use more than one source for each changeset.

That's often my practice too; even when using Bing imagery after a survey I
will make one 'pass' across the area tracing and then a second pass adding
the surveyed names and POIs.

>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).

Curiously enough I usually do it the other way: survey first and then trace
Bing imagery once I get home, before uploading the survey as a separate
changeset.  On the other hand, if adding missing roads from the United
Kingdom's Ordnance Survey data, I will trace first and then survey (perhaps
some time later...).

-- 
Ed Avis <eda at waniasset.com>