On 09/07/2010, at 1:07 AM, David Carmean wrote:
They use a shapefile generated from
a filtered snapshot of OSM data--leaving only roads--as a base layer.
If they do nothing else but serve this one-time snapshot as a base
layer, what are their obligations?
My opinion is that since they've changed the data (stripping out the non-road
bits) that creates a derived database, which strictly speaking has to be
provided. However like with similar situations with the GPL, this may not be as
onerous as it sounds - many people package binaries of GPL'd software without
putting the source along side it.
Per ODBl 4.6b, you would just need to tell anyone asking the filtering
algorithm you used - for example remove all ways that don't have a highway=*
tag (in machine readable form).
Secondly, what if one of their staff, being unfamiliar with OSM but a
GIS expert, sees a problem with one or more roads about which they
have personal knowledge, and fixes those problems in the GIS data
only--then publishing the result as a mapserver layer only. What are
their obligations in this case?
Making either the derived database or the changes available. Since it's not
algorithmic, you have to provide a diff (or the whole derived db) if someone
asked for it.
If you are doing a one-off import, you'd just need to either have a copy of the
original to produce a diff upon request, or be willing to produce a dump of the
OSM-based part of the database.
If they're not doing a one-off import of OSM data, you'd presumably have some
way of merging you local changes with the upstream changes, so a diff should be
easy.
Third: there is the usual problem/condition (depending on your
political leanings) of divergence in the tag values. For example,
surface=Dirt vs. surface=dirt, surface=cement vs. surface=concrete,
etc. I'd certainly want to fix that, but if I were that agency, I woulnd't
have the time/skills to make a 'bot fix back in the OSM database.
Strictly speaking you'd have to provide those changes. But if it's a rendering
rule then it's not a DB change, and if it's automated you can just provide the
algorithm change surface=Dirt to surface=dirt.
The two things to note are, 1) like with the GPL, you have to offer it to the
recipients, however if it's not interesting (e.g. just filtering), no-one
will probably ask, and 2) if it's an algorithmic change, you just have to
provide the algorithm.
--
James
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